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金澤裕樹

徳島大学

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2024年12月20日更新

職名: 助教
電話: 088-633-9059
電子メール: yk@tokushima-u.ac.jp
学歴: 1998/3: 京都医療技術短期大学診療放射線技術学科卒業
2008/3: 金沢大学大学院医学系研究科保健学専攻博士前期課程修了
2012/3: 金沢大学大学院医学系研究科保健学専攻博士後期課程修了
学位: 博士(保健学) (金沢大学) (2012年3月)
職歴・経歴: 1998/4: 京都第一赤十字病院放射線科診療放射線技師
2011/4: 京都第一赤十字病院放射線診断科 MR技術係長
2013/4: 京都大学大学院医学研究科放射線医学講座(画像診断学・核医学)特定助教
2014/4: 徳島大学大学院ヘルスバイオサイエンス研究部医用情報科学講座助教
2015/4: 徳島大学大学院医歯薬学研究部医用画像情報科学分野助教

専門分野・研究分野: 放射線科学
医用イメージング (Medical Imaging)

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2024年12月20日更新

専門分野・研究分野: 放射線科学
医用イメージング (Medical Imaging)
担当経験のある授業科目: MRI技術学 (学部)
先端医用画像情報学・先端数理統計学 (大学院)
先端医用画像情報学・先端数理統計学演習 (大学院)
先端医療と放射線 (学部)
医用画像情報学Ⅱ(臨床画像解析) (学部)
実践医療安全管理学 (学部)
実践医療安全管理学実習 (学部)
実践臨床技能実習 (学部)
放射線治療技術学臨床実習 (学部)
放射臨床実習(出席情報確認用) (学部)
放射臨床実習(補講出席状況確認用) (学部)
核医学技術学臨床実習 (学部)
核医学検査技術学臨床実習 (学部)
画像病態学 (学部)
磁気共鳴画像学 (学部)
臨床画像検査学 (学部)
診療画像学Ⅰ(一般撮影・透視撮影・歯科撮影検査) (学部)
診療画像学Ⅱ(各種造影・超音波・眼底撮影検査) (学部)
診療画像学実習 (学部)
診療画像学臨床実習 (学部)
指導経験: 14人 (修士), 1人 (博士)

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2024年12月20日更新

専門分野・研究分野: 放射線科学
医用イメージング (Medical Imaging)

研究テーマ: 核磁気共鳴画像
核磁気共鳴画像 (MRIを用いた組織血行動態解析, 生体におけるMR緩和時間測定法開発と応用, MRIを用いた生体情報の可視化)

著書

金澤裕樹 :
MRIを中心としたRSNA2023トピックス,
産業開発機構株式会社, 2024年2月. 金澤裕樹 :
生体構造・代謝物マッピングの最新動向-MT，MWF，CESTイメージングを中心に,
株式会社インナービジョン, 東京, 2023年. 金澤裕樹 :
その他のMR撮像法(MRIによる血管撮像法，脂肪抑制法，MR hydrography), --- 図解診療放射線技術実践ガイド第4版 ---,
文光堂, 東京, 2020年1月. 金澤裕樹 :
MRIの原理と各種撮像シーケンス, --- MRI再入門放射線科医のためのマストアイテム Part 1 ---,
学研メディカル秀潤社, 東京, 2020年1月. 金澤裕樹 :
骨盤部MRIに見る信号特性と雑音対策─撮像技術と画像処理, --- Step up MRI 2016 明日の臨床に向けた撮像法，今日の検査に役立つ撮像テクニック ---,
インナービジョン, 東京, 2016年8月.

論文

Yasuhisa Kanematsu, Yuki Kanazawa, Kenji Shimada, Masaaki Korai, Takeshi Miyamoto, Shu Sogabe, Manabu Ishihara, Izumi Yamaguchi, Takeshi Oya, Nobuaki Yamamoto, Yuki Yamamoto, Miyoshi Mitsuharu, Masafumi Harada and Yasushi Takagi :
Characterization of carotid plaques using chemical exchange saturation transfer imaging,
Neuroradiology, Vol.66, No.9, 1617-1624, 2024.

(要約): The preoperative assessment of carotid plaques is necessary to render revascularization safe and effective. The aim of this study is to evaluate the usefulness of chemical exchange saturation transfer (CEST)-MRI, particularly amide proton transfer (APT) imaging as a preoperative carotid plaque diagnostic tool. We recorded the APT signal intensity on concentration maps of 34 patients scheduled for carotid endarterectomy. Plaques were categorized into group A (APT signal intensity ≥ 1.90 E-04; n = 12) and group B (APT signal intensity < 1.90 E-04; n = 22). Excised plaques were subjected to histopathological assessment and, using the classification promulgated by the American Heart Association, they were classified as intraplaque hemorrhage-positive [type VI-positive (tVI)] and -negative [no intraplaque hemorrhage (tVI)]. Of the 34 patients, 22 (64.7%) harbored tVI- and 12 (35.3%) had tVI plaques. The median APT signals were significantly higher in tVI- than tIVI patients (2.43 E-04 (IQR = 0.98-4.00 E-04) vs 0.54 E-04 (IQR = 0.14-1.09 E-04), p < .001). Histopathologically, the number of patients with tVI plaques was significantly greater in group A (100%, n = 12) than group B (45%, n = 22) (p < .01). The number of symptomatic patients or asymptomatic patients with worsening stenosis was also significantly greater in group A than group B (75% vs 36%, p < .01). In unstable plaques with intraplaque hemorrhage and in patients with symptoms or progressive stenosis, the ATP signals were significantly elevated. CEST-MRI studies has the potential for the preoperative assessment of the plaques' characteristics.
(キーワード): Humans / Male / Female / Aged / Carotid Stenosis / Magnetic Resonance Imaging / Middle Aged / Endarterectomy, Carotid / Plaque, Atherosclerotic / Sensitivity and Specificity / Image Interpretation, Computer-Assisted
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s00234-024-03401-3
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 38866959; ● Search Scopus @ Elsevier (PMID): 38866959; ● Search Scopus @ Elsevier (DOI): 10.1007/s00234-024-03401-3

(DOI: 10.1007/s00234-024-03401-3, PubMed: 38866959) Yuki Kanazawa, Yo Taniguchi, Masafumi Harada, Kosuke Ito and Yoshitaka Bito :
Visualization of Human Brain Cortical Layers Using Quantitative Parameter Mapping on a 3 Tesla Scanner,
Proceedings of ISMRM, Vol.33, 2933, 2024. Ohshiro Ryuji, Yuki Kanazawa, Akihiro Haga and Masafumi Harada :
Development of numerical phantom converting from electron microscopic analysis to multi-component water fraction for MRI simulator.,
Proceedings of ISMRM, Vol.33, 2038, 2024. Shun Kitano, Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Hiroaki Hayashi, Yuki Matsumoto, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Conversion Map from Quantitative Parameter Mapping to Myelin Water Fraction: Comparison with R1·R2* and Myelin Water Fraction in White Matter.,
Magma, 2024.

(要約): To clarify the relationship between myelin water fraction (MWF) and R⋅R and to develop a method to calculate MWF directly from parameters derived from QPM, i.e., MWF converted from QPM (MWF). Subjects were 12 healthy volunteers. On a 3 T MR scanner, dataset was acquired using spoiled gradient-echo sequence for QPM. MWF and R⋅R maps were derived from the multi-gradient-echo (mGRE) dataset. Volume-of-interest (VOI) analysis using the JHU-white matter (WM) atlas was performed. All the data in the 48 WM regions measured VOI were plotted, and quadratic polynomial approximations of each region were derived from the relationship between R·R and the two-pool model-MWF. The R·R map was converted to MWF map. MWF atlas template was generated using converted to MWF from R·R per WM region. The mean MWF and R·R values for the 48 WM regions were 11.96 ± 6.63%, and 19.94 ± 4.59 s, respectively. A non-linear relationship in 48 regions of the WM between MWF and R·R values was observed by quadratic polynomial approximation (R ≥ 0.963, P < 0.0001). MWF map improved image quality compared to the mGRE-MWF map. Myelin water atlas template derived from MWF may be generated with combined multiple WM regions.
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s10334-024-01155-w
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 38581455; ● Search Scopus @ Elsevier (PMID): 38581455; ● Search Scopus @ Elsevier (DOI): 10.1007/s10334-024-01155-w

(DOI: 10.1007/s10334-024-01155-w, PubMed: 38581455) Natsuki Ikemitsu, Yuki Kanazawa, Akihiro Haga, Hiroaki Hayashi, Yuki Matsumoto and Masafumi Harada :
Determination of Alzheimer's disease based on morphology and atrophy using machine learning combined with automated segmentation,
Acta Radiologica, Vol.65, No.4, 359-366, 2024.

(要約): To evaluate the degree of cerebral atrophy for Alzheimer's disease (AD), voxel-based morphometry has been performed with magnetic resonance imaging. Detailed morphological changes in a specific tissue area having the most evidence of atrophy were not considered by the machine-learning technique. To develop a machine-learning system that can capture morphology features for determination of atrophy of brain tissue in early-stage AD and classification of healthy participants or patients. Three-dimensional T1-weighted (3D-T1W) data were obtained from AD Neuroimaging Initiative (200 healthy controls and 200 patients with early-stage AD). Automated segmentation of 3D-T1W data was performed. Deep learning (DL) and support vector machine (SVM) were trained using 66-segmented volume values as input and AD diagnosis as output. DL was performed using 66 volume values or gray matter (GM) and white matter (WM) volume values. SVM learning was performed using 66 volume values and six regions with high variable importance. 3D convolutional neural network (3D-CNN) was trained using the segmented images. Accuracy and area under curve (AUC) were obtained. Variable importance was evaluated from logistic regression analysis. DL for GM and WM volume values, accuracy 0.6; SVM for all volume values, accuracy 0.82 and AUC 0.81; DL for all volume values, accuracy 0.82 and AUC 0.8; 3D-CNN using segmental images of the whole brain, accuracy 0.5 and AUC 0.51. SVM using volume values of six regions, accuracy 0.82; image-based 3D-CNN, highest accuracy 0.69. Our results show that atrophic features are more considerable than morphological features in the early detection of AD.
(キーワード): Alzheimer's disease / magnetic resonance imaging / convolutional neural network / deep learning / support vector machine
(出版サイトへのリンク): ● Publication site (DOI): 10.1177/02841851231218384
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 38196180; ● Search Scopus @ Elsevier (PMID): 38196180; ● Search Scopus @ Elsevier (DOI): 10.1177/02841851231218384

(DOI: 10.1177/02841851231218384, PubMed: 38196180) Hiroaki Hayashi, Tatsuya Maeada, Sota Goto, Kazuki Takegami, Takashi Asahara, Rina Nishigami, Daiki KObayashi, Yuki Kanazawa and Kazuta Yamashita :
Direct dose measurement method during chest CT examination by taking into consideration the X-ray incident direction,
European Congress of Radiology, No.EPOS, C-11117, 2024.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2024/C-11117
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2024/C-11117

(DOI: 10.26044/ecr2024/C-11117) Daiki Kobayashi, Hiroaki Hayashi, Rina Nishigami, Tatsuya Maeda, Takashi Asahara, Yuki Kanazawa, Akitoshi Katsumata, Natsukmi Kimoto and Shuochiro Yamamoto :
A blurring correction method suitable to analyze quantitative x-ray images derived from energy-resolving photon counting detector,
Physics in Medicine and Biology, Vol.Accepted, 2024.

(要約): Objective. The purpose of this study is to propose a novel blurring correction method that enables accurate quantitative analysis of the object edge when using energy-resolving photon counting detectors (ERPCDs). Although the ERPCDs have the ability to generate various quantitative analysis techniques, such as the derivations of effective atomic number (Zeff) and bone mineral density (BMD) values, at the object edge in these quantitative images, accurate quantitative information cannot be obtained. This is because image blurring prevents the gathering of accurate primary X-ray attenuation information. Approach. We developed the following procedure for blurring correction. A 5 × 5 pixels masking region was set as the processing area, and the pixels affected by blurring were extracted from the analysis of pixel value distribution. The blurred pixel values were then corrected to the proper values estimated by analyzing minimum and/or maximum values in the set mask area. The suitability of our correction method was verified by a simulation study and an experiment using a prototype ERPCD. Main results. When Zeff image of aluminum objects (Zeff = 13) were analyzed without applying our correction method, regardless of raw data or correction data applying a conventional edge enhancement method, the proper Zeff values could not be derived for the object edge. In contrast, when applying our correction method, 82% of pixels affected by blurring were corrected and the proper Zeff values were calculated for those pixels. As a result of investigating the applicability limits of our method through simulation, it was proven that it works effectively for objects with 4 × 4 pixels or more. Significance. Our method is effective in correcting image blurring when the quantitative image is calculated based on multiple images. It will become an in-demand technology for putting a quantitative diagnosis into actual medical examinations.
(出版サイトへのリンク): ● Publication site (DOI): 10.1088/1361-6560/ad3119
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1088/1361-6560/ad3119

(DOI: 10.1088/1361-6560/ad3119) Nagi Masumoto, Motoharu Sasaki, Yuji Nakaguchi, Takeshi Kamomae, Yuki Kanazawa and Hitoshi Ikushima :
Knowledge-based model building for treatment planning for prostate cancer using commercial treatment planning quality assurance software tools,
Radiological Physics and Technology, Vol.17, No.1, 337-345, 2024.

(要約): This study devised a method to efficiently launch the RapidPlan model for volumetric-modulated arc therapy for prostate cancer in small- and medium-sized facilities using high-quality treatment plans with the PlanIQ software as a reference. Treatment plans were generated for 30 patients with prostate cancer to construct the RapidPlan model using PlanIQ as a reference. In the context of PlanIQ-referenced treatment planning, treatment plans were developed, such that the feasibility dose-volume histogram of each organ-at-risk fell within F ≤ 0.1. For validation of the RapidPlan model, treatment plans were formulated for 20 patients using both RapidPlan and PlanIQ, and the differences were evaluated. The results of RapidPlan model validity assessment revealed that the RapidPlan-produced treatment plans exhibited higher quality in 11 of 20 patients. No significant differences were found between the treatment plans. In conclusion, high-quality treatment plans formulated using PlanIQ as reference facilitated efficient implementation of RapidPlan modeling.
(キーワード): RapidPlan / PlanIQ / treatment planning quality
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-023-00759-6
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 37938420; ● Search Scopus @ Elsevier (PMID): 37938420; ● Search Scopus @ Elsevier (DOI): 10.1007/s12194-023-00759-6

(DOI: 10.1007/s12194-023-00759-6, PubMed: 37938420) Daiki Chiba, Yuki Kanazawa, Tosiaki Miyati, Masafumi Harada, Mitsuharu Miyoshi, Hiroaki Hayashi and Akihiro Haga :
Simplified assessment for chemical exchanged saturation transfer (CEST) imaging: local offset frequency and CEST effect,
Radiological Physics and Technology, Vol.17, No.1, 93-102, 2024.

(要約): The aim of this study is to develop a novel phantom for the evaluation of clinical CEST imaging settings, e.g., B0 and B1 field inhomogeneities, CEST contrast, and post-processing. We made a phantom composed of two slice sections: a grid section for local offset frequency evaluation and a sample section for CEST effect evaluation using different concentrations of an egg white albumin solution. On a 3 Tesla MR scanner, a phantom study was performed using CEST imaging; the mean B1 amplitudes were set at 1.2 and 1.9 µT, and CEST images with and without B0 corrections were acquired. Next, region of interest (ROI) analysis was performed for each slice. Then, CEST images with and without B0 corrections were compared at each B1 amplitude. The B0 corrected Z-spectrums at each local region in the grid section showed a shifting of the curve bottom to 0 ppm. Z-spectrum at B1 = 1.9 µT showed a broader curve shape than that at 1.2 µT. Moreover, MTRasym values at 3.5 ppm for each albumin sample at B1 = 1.9 µT were about two times higher than those at 1.2 µT. Our phantom enabled us to evaluate and optimize B0 inhomogeneity and the CEST effect at the B1 amplitude.
(キーワード): Magnetic Resonance Imaging / Phantoms, Imaging / Albumins
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-023-00752-z
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 37897684; ● Summary page in Scopus @ Elsevier: 2-s2.0-85174963843

(DOI: 10.1007/s12194-023-00752-z, PubMed: 37897684, Elsevier: Scopus) Yuki Kanazawa, Natsuki Ikemitsu, Yuki Kinjyo, Masafumi Harada, Hiroaki Hayashi, Yo Taniguchi, Kosuke Ito, Yoshitaka Bito, Yuki Matsumoto and Akihiro Haga :
Differences of white matter structure for diffusion kurtosis imaging using voxel-based morphometry and connectivity analysis,
BJR Open, Vol.6, No.1, 1-7, 2024.

(要約): In a clinical study, diffusion kurtosis imaging (DKI) has been used to visualize and distinguish white matter (WM) structures' details. The purpose of our study is to evaluate and compare the diffusion tensor imaging (DTI) and DKI parameter values to obtain WM structure differences of healthy subjects. Thirteen healthy volunteers (mean age, 25.2 years) were examined in this study. On a 3-T MRI system, diffusion dataset for DKI was acquired using an echo-planner imaging sequence, and T-weghted (Tw) images were acquired. Imaging analysis was performed using Functional MRI of the brain Software Library (FSL). First, registration analysis was performed using the Tw of each subject to MNI152. Second, DTI (eg, fractional anisotropy [FA] and each diffusivity) and DKI (eg, mean kurtosis [MK], radial kurtosis [RK], and axial kurtosis [AK]) datasets were applied to above computed spline coefficients and affine matrices. Each DTI and DKI parameter value for WM areas was compared. Finally, tract-based spatial statistics (TBSS) analysis was performed using each parameter. The relationship between FA and kurtosis parameters (MK, RK, and AK) for WM areas had a strong positive correlation (FA-MK, = 0.93; FA-RK, = 0.89) and a strong negative correlation (FA-AK, = 0.92). When comparing a TBSS connection, we found that this could be observed more clearly in MK than in RK and FA. WM analysis with DKI enable us to obtain more detailed information for connectivity between nerve structures. Quantitative indices of neurological diseases were determined using segmenting WM regions using voxel-based morphometry processing of DKI images.
(出版サイトへのリンク): ● Publication site (DOI): 10.1093/bjro/tzad003
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 38352183; ● Search Scopus @ Elsevier (PMID): 38352183; ● Search Scopus @ Elsevier (DOI): 10.1093/bjro/tzad003

(DOI: 10.1093/bjro/tzad003, PubMed: 38352183) Rina Nishigami, Hiroaki Hayashi, Daiki Kobayashi, Tatsuya Maeada, Takashi Asahara, Yuki Kanazawa, Natsumi Kimoto and Shuichiro Yamamoto :
Applicability of high tube voltage imaging to achieve accurate quantitative images when applying photon counting detectors to general radiography,
Proceedings of SPIE, 2024. Daisuke Satoh, Motoharu Sasaki, Yuji Nakaguchi, Takeshi Kamomae, Takashi Kawanaka, Akiko Kubo, Chisato Tonoiso, Yuki Kanazawa, Masataka Oita, Akimi Kajino, Akira Tsuzuki and Hitoshi Ikushima :
Differences between professionals in planning treatment for patients with stage III lung cancer using treatment-planning QA software,
Reports of Practical Oncology and Radiotherapy, Vol.28, No.5, 671-680, 2023.

(要約): The quality of treatment planning for stage III non-small cell lung cancer varies within and between facilities due to the different professions involved in planning. Dose estimation parameters were calculated using a feasibility dose-volume histogram (FDVH) implemented in the treatment planning quality assurance software PlanIQ. This study aimed to evaluate differences in treatment planning between occupations using manual FDVH-referenced treatment planning to identify their characteristics. The study included ten patients with stage III non-small cell lung cancer, and volumetric-modulated arc therapy was used as the treatment planning technique. Fifteen planners, comprising five radiation oncologists, five medical physicists, and five radiological technologists, developed treatment strategies after referring to the FDVH. Medical physicists had a higher mean dose at D98% of the planning target volume (PTV) and a lower mean dose at D2% of the PTV than those in other occupations. Medical physicists had the lowest irradiation lung volumes (V5 Gy and V13 Gy) compared to other professions, and radiation oncologists had the lowest V20 Gy and mean lung dose. Radiological technologists had the highest irradiation volumes for dose constraints at all indexes on the normal lung volume. The quality of the treatment plans developed in this study differed between occupations due to their background expertise, even when an FDVH was used as a reference. Therefore, discussing and sharing knowledge and treatment planning techniques among professionals is essential to determine the optimal treatment plan for each facility and patient.
(キーワード): Non-small-cell lung cancer / PlanIQ / Treatment planning quality / Volumetric-modulated arc therapy
(出版サイトへのリンク): ● Publication site (DOI): 10.5603/rpor.97511
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 38179286; ● Search Scopus @ Elsevier (PMID): 38179286; ● Search Scopus @ Elsevier (DOI): 10.5603/rpor.97511

(DOI: 10.5603/rpor.97511, PubMed: 38179286) Rina Nishigami, Hiroaki Hayashi, Daiki Kobayashi, Cheonghae Lee, Tatsuya Maeda, Takashi Asahara, Yuki Kanazawa, Natsumi Kimoto and Shuichiro Yamamoto :
Simulation study on functional images to optimize radiographic condition using energy resolving photon counting detector,
The 2023 IEEE Nuclear Science Symposium and Medical Imaging Conference, 2023.

(出版サイトへのリンク): ● Publication site (DOI): 10.1109/NSSMICRTSD49126.2023.10338161
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1109/NSSMICRTSD49126.2023.10338161

(DOI: 10.1109/NSSMICRTSD49126.2023.10338161) Takashi Asahara, Hiroaki Hayashi, Tatsuya Maeada, Sota Goto, Daiki Kobayashi, Cheongha Lee, Yuki Kanazawa, Naoki Maeda and Mitsugi Honda :
A wearable active-type dosimeter having novel functions to derive both incident direction and absolute dose of scattered X-rays during IVR procedures,
ECR 2023, C-10352, 2023.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2023/C-10352
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2023/C-10352

(DOI: 10.26044/ecr2023/C-10352) Kazuki Takegami, Yuki Kanazawa, Tatsuya Maeda, Cheonghae Lee, Rina Nishigami, Takashi Asahara, Sota Goto, Daiki KObayashi, Miku Ando, Yuki Kanazawa, Kazuta Yamashita, Kosaku Higashino, Shuichi Murakami, Takeshi Konishi and Motochika Maki :
Thyroid dose reduction shield with the generation of less artifacts used for fast chest CT examination,
Radiation Physics and Chemistry, Vol.203, 110635, 2023.

(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.radphyschem.2022.110635
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1016/j.radphyschem.2022.110635

(DOI: 10.1016/j.radphyschem.2022.110635) Daiki Kobayashi, Hiroaki Hayashi, Rina Nishigami, Cheonghae Lee, Tastuya Maeda, Yuki Kanazawa, Akitoshi Katsumata, Natsuki Kimoto and Shuichiro Yamashita :
Blurring correction for calculating functional images using an energy resolving photon counting detector,
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2023. Rina Nishigami, Hiroaki Hayashi, Daiki Kobayashi, Cheonghae Lee, Tatsuya Maeda, Takashi Asahara, Yuki Kanazawa, Natsumi Kimoto and Shuichiro Yamamoto :
Simulation study on functional images to optimize radiographic condition using energy resolving photon counting detector,
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2023. Cheonghae Lee, Hiroaki Hayashi, Daiki Kobayashi, Rina Nishigami, Tatsuya Maeda, Takashi Asahara, Yuki Kanazawa, Akitoshi Katsumata, Natsuki Kimoto and Shuichiro Yamamoto :
Automatic determination algorithm of intrinsic parameters on response function of energy-resolving photon counting imaging detector,
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2023. Takashi Asahara, Hiroaki Hayashi, Tatsuya Maeda, Sota Goto, Daiki Kobayashi, Rina Nishigami, Cheonghae Lee, Miku Ando, Yuki Kanazawa, Satoshi Imajo, Kazuta Yamashita and Kosaku Higashino :
A wearable active-type X-ray dosimeter having novel functions to derive both incident direction and absolute exposure dose,
Radiation Physics and Chemistry, Vol.208, 110932, 2023.

(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.radphyschem.2023.110932
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-85152601913

(DOI: 10.1016/j.radphyschem.2023.110932, Elsevier: Scopus) Yuki Kanazawa, KITANO Shun, Masafumi Harada, Yo Taniguchi, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Myelin Water Atlas Template Derived from Quantitative Parameter Mapping,
Proceedings of ISMRM, Vol.32, No.2630, 2023. Yuki Kanazawa, Tosiaki Miyati, Masafumi Harada, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Yasuhisa Kanematsu and Yasushi Takagi :
Evaluation of Biological Metabolic Activity within an Atherosclerotic Plaque using Chemical Exchange Saturation Transfer Imaging,
Proceedings of ISMRM, Vol.32, No.2982, 2023. Mayuka Seguchi, Yuki Kanazawa, Tosiaki Miyati, Masafumi Harada, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Yasuhisa Kanematsu and Yasushi Takagi :
Diffusion weighted-viscosity imaging for atherosclerotic plaques,
Proceedings of ISMRM, Vol.32, No.1519, 2023. Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Hiroaki Hayashi, Takashi Abe, Maki Ohtomo, Yuki Matsumoto, Masaharu Ono, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Myelin-weighted imaging derived from quantitative parameter mapping,
European Journal of Radiology, Vol.156, No.110525, 1-9, 2022.

(要約): We developed a novel method which is applicable to visualize contrast according to myelin components in the human brain using relaxation time derived from quantitative parameter mapping magnetic resonance imaging (QPM-MRI). Using healthy volunteer data (n = 10), we verified that our method demonstrated that the myelin-weighted contrast increased proportionally by products R and R*, i.e., QPM-myelin-weighted image, in which modified T-weighted/T-weighted (Tw/Tw) ratio mapping method was applied. We compared measurement values in white matter (WM) and gray matter (GM) regions of the Tw/Tw ratio and R·R* product maps of healthy volunteers. Linear regression analysis between each value. Mann Whitney U test between WM and GM signals in each myelin map. In addition, Additionally, QPM-myelin-weighted image was applied to a 32-year-old female MS patient. Linear regression analysis showed a highly significant correlation between conventional Tw/Tw ratios and R·R* products derived from QPM (R = 0.73, P < 0.0001). Moreover, there is a significant difference between WM and GM structures in each myelin images (both, P < 0.0001). Additionally, in a clinical case, MS lesions enabled observation of not only MS plaques but also heterogeneous myelin signal loss associated with demyelination more clearly than Tw image and conventional Tw/Tw ratio image. Our myelin-weighted imaging technique using QPM may be useful for myelin visualization and is expected to become independent of measurement conditions due to having quantitative characteristics of QPM itself.
(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.ejrad.2022.110525
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 36166986; ● Search Scopus @ Elsevier (PMID): 36166986; ● Search Scopus @ Elsevier (DOI): 10.1016/j.ejrad.2022.110525

(DOI: 10.1016/j.ejrad.2022.110525, PubMed: 36166986) Natsuki Ikemitsu, Yuki Kanazawa, Masafumi Harada, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yo Taniguchi, Yoshitaka Bito and Akihiro Haga :
Determination of white matter structure index for voxel basedmorphometry and connectivity analysis.,
European Congress of Radiology (EPOS), 10, 2022. Nagomi Fukuda, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga :
Development of a B1 correction method without additional scanning VFA T1 map.,
European Congress of Radiology (EPOS), 10, 2022. Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi and Yuki Matsumoto :
Evaluation of brain tumor and surrounding tissue activity using multi-pool CEST imaging on 3 Tesla scanner,
Proceedings of ISMRM, Vol.31, No.4285, 2022. Nagomi Fukuda, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga :
Development of self-calibrating B1 correction for three-dimensional variable flip angle T1 mapping,
Proceedings of ISMRM, Vol.31, No.3218, 2022. Shun Kitano, Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Conversion map from quantitative parameter mapping to myelin water fraction,
Proceedings of ISMRM, Vol.31, No.3052, 2022. Natsuki Ikemitsu, Yuki Kanazawa, Akihiro Haga, Hiroaki Hayashi, Yuki Matsumoto and Masafumi Harada :
Determination of Alzheimer's disease based on morphology and atrophy using machine learning combined with automated segmentation.,
Proceedings of ISMRM, Vol.31, No.3263, 2022. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Yo Taniguchi, Masaharu Ono and Yoshitaka Bito :
Quantitative parameter mapping of contrast agent concentration and relaxivity and brain tumor extracellular pH,
Scientific Reports, 2022.

(要約): In clinical magnetic resonance imaging, gadolinium-based contrast agents are commonly usedfor detecting brain tumors and evaluating the extent of malignancy. We present a new method toevaluate relaxivity (r1) and contrast agent concentration separately in contrast-enhanced lesions usingquantitative parameter mapping (QPM). Furthermore, we also aimed to estimate the extracellularpH (pHe) of tumor lesions. We demonstrated that it is possible to evaluate pathophysiological tumorchanges due to therapeutic efficacy by measuring r1 in contrast-enhanced lesions. In this study, theprimary brain tumor group showed significantly higher r1 values than other brain disease groups(P< 0.001). Moreover, mean pHe value showed a trend for tumor malignancy having a lower pHevalue and primary brain tumor having a significantly lower pHe than other brain diseases (P< 0.001).Our results might suggest that QPM can separately quantify r1 and CA concentration in brain tumorsand that pHe brain tumor mapping could serve as a tumor biomarker. In conclusion, our method haspotential clinical applications for assessing the treatment effects.
(キーワード): MRI (MRI) / 脳腫瘍 (brain tumor) / 医用画像 (medical image)
(徳島大学機関リポジトリ): ● Metadata: 116994
(出版サイトへのリンク): ● Publication site (DOI): 10.1038/s41598-022-05711-z
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1038/s41598-022-05711-z

(徳島大学機関リポジトリ: 116994, DOI: 10.1038/s41598-022-05711-z) Madoka Kohno, ANAYT ULLA, Rina Taniguchi, Akane Ohishi, Kako Hirayama, Yuma Takemura, Shoichiro Takao, Yuki Kanazawa, Yuki Matsumoto, Masafumi Harada, Tomoya Fukawa, Hiro-omi Kanayama, Takayuki Uchida, Toshio Suzuki and Takeshi Nikawa :
Daily Dietary Supplementation with Steamed Soybean Improves Muscle Volume and Strength in Healthy People Lacking Exercise.,
Journal of Nutritional Science and Vitaminology, Vol.68, No.6, 521-526, 2022.

(要約): Various dietary protein supplements are used by the elderly and bedridden to maintain their skeletal muscle mass and functions. High-quality proteins act as an anabolic driver and help to improve muscle strength and performance. Previously, we reported that soy protein significantly attenuates denervation-induced loss of muscle mass and myofiber cross sectional area in mice with inhibition of ubiquitination and degradation of IRS-1 in tibialis anterior muscle. It also increased muscle volume and strength in bedridden patients. In the present study, we investigated the effects of dietary soybean supplementation on muscle functions in taxi drivers lacking vigorous physical exercise. We conducted a case-control study on 25 healthy, male taxi drivers between the ages of 36 and 71 y performing minimal physical exercise. They were divided into two dietary groups: the soybean diet group (n=13) who ate daily meals (dinner) supplemented with 50 g of steamed soybean for 30 d and the control diet group (n=12) who received no soybean supplement. Next, we measured the muscle cross-sectional area (CSA) and muscle strength and function in both the groups before and after 30 d of soybean intake. The body weights of both diet groups did not differ significantly over time. However, after 30 d of soybean supplementation, the soybean-fed group developed significantly higher muscle CSA and grip strength compared to the control groups. In conclusion, dietary soybean supplementation improved muscle function in taxi drivers who lacked exercise.
(キーワード): Male / Animals / Mice / Soybeans / Case-Control Studies / Muscle, Skeletal / Dietary Supplements / Muscle Strength / Dietary Proteins
(出版サイトへのリンク): ● Publication site (DOI): 10.3177/jnsv.68.521
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 36596550; ● CiNii @ 国立情報学研究所 (CRID): 1390576118538657152; ● Search Scopus @ Elsevier (PMID): 36596550; ● Search Scopus @ Elsevier (DOI): 10.3177/jnsv.68.521

(DOI: 10.3177/jnsv.68.521, PubMed: 36596550, CiNii: 1390576118538657152) Cheonghae Lee, Hiroaki Hayashi, Natsumi Kimoto, Tatsuya Maeda, Miku Ando, Yuki Kanazawa, Akitoshi Katsumata, Shuichiro Yamamoto and Masahiro Okada :
Bone and soft-tissue images extraction through derivation of effective atomic number image using photon-counting detector.,
Proceedings of IEEE(MIC), 5, 2021.

(出版サイトへのリンク): ● Publication site (DOI): 10.1109/NSS/MIC44867.2021.9875683
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-85139133825

(DOI: 10.1109/NSS/MIC44867.2021.9875683, Elsevier: Scopus) Natsumi Kimoto, Hiroaki Hayashi, Cheonghae Lee, Tatsuya Maeda, Miku Ando, Yuki Kanazawa, Akitoshi Katsumata, Shuichiro Yamamoto and Masahiro Okada :
A novel algorithm for extracting soft-tissue and bone images measured using a photon-counting type X-ray imaging detector with the help of effective atomic number analysis,
Applied Radiation and Isotopes, Vol.176, No.109822, 12, 2021.

(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.apradiso.2021.109822
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1016/j.apradiso.2021.109822

(DOI: 10.1016/j.apradiso.2021.109822) Hasegawa Yu, Akihiro Haga, Sakata Dousatsu, Yuki Kanazawa, Masahide Tominaga, Motoharu Sasaki, Imae Toshikazu and Nakagawa Keiichi :
Estimation of X-ray Energy Spectrum of Cone-Beam Computed Tomography Scanner Using Percentage Depth Dose Measurements and Machine Learning Approach,
Journal of the Physical Society of Japan, Vol.90, 074801-1-074801-7, 2021.

(出版サイトへのリンク): ● Publication site (DOI): 10.7566/JPSJ.90.074801
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.7566/JPSJ.90.074801

(DOI: 10.7566/JPSJ.90.074801) Naoki Maeda, Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Derivation of Water Exchange Constants between Components using Quantitative Parameter Mapping (QPM),
Proceedings of ISMRM, Vol.29, No.3069, 2021. Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Syun Kitano, Nagomi Fukuda, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Myelin imaging derived quantitative parameter mapping compared to myelin water fraction,
Proceedings of ISMRM, Vol.29, No.2828, 2021. Hiroaki Hayashi, Natsumi Kimoto, Tatsuya Maeda, Emi Tomita, Takashi Asahara, Sota Goto, Yuki Kanazawa, Yasufumi Shitakubo, Kanako Sakuragawa, Hitoshi Ikushima, Tohru Okazaki and Takuya Hashizume :
A disposable OSL dosimeter for in-vivo measurement of rectum dose during brachytherapy,
Medical Physics, Vol.Online ahead of print, 2021.

(要約): We aimed to develop a disposable rectum dosimeter and to demonstrate its ability to measure exposure dose to the rectum during brachytherapy for cervical cancer treatment using high-dose rate Ir. Our rectum dosimeter measures the dose with an optically stimulated luminescence (OSL) sheet which was furled to a catheter. The catheter we used is 6 mm in diameter; therefore, it is much less invasive than other rectum dosimeters. The rectum dosimeter developed in this study has the characteristics of being inexpensive and disposable. It is also an easy-to-use detector that can be individually sterilized, making it suitable for clinical use. To obtain a dose calibration curve, phantom experiments were performed. Irradiation was performed using a cubical acrylic phantom, and the response of the OSL dosimeter was calibrated with the calculation value predicted by the treatment planning system (TPS). Additionally, the dependence of catheter angle on the dosimeter position and repeatability were evaluated. We also measured the absorbed dose to the rectum of patients who were undergoing brachytherapy for cervical cancer (n = 64). The doses measured with our dosimeters were compared with the doses calculated by the TPS. In order to examine the causes of large differences between measured and planned doses, we classified the data into common and specific cases when performing this clinical study. For specific cases, the following three categories were considered: (a) patient movement, (b) gas in the vagina and/or rectum, and (c) artifacts in the X-ray image caused by applicators. A dose calibration curve was obtained in the range of 0.1 Gy-10.0 Gy. From the evaluation of the dependence of catheter angle on the dosimeter position and repeatability, we determined that our dosimeter can measure rectum dose with an accuracy of 3.1% (k = 1). In this clinical study, we succeeded in measuring actual doses using our rectum dosimeter. We found that the deviation of the measured dose from the planned dose was derived to be 12.7% (k = 1); this result shows that the clinical study included large elements of uncertainty. The discrepancies were found to be due to patient motion during treatment, applicator movement after planning images were taken, and artifacts in the planning images. We present the idea that a minimally invasive rectum dosimeter can be fabricated using an OSL sheet. Our clinical study demonstrates that a rectum dosimeter made from an OSL sheet has sufficient ability to evaluate rectum dose. Using this dosimeter, valuable information concerning organs at risk can be obtained during brachytherapy.
(出版サイトへのリンク): ● Publication site (DOI): 10.1002/mp.14857
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 33760234; ● Search Scopus @ Elsevier (PMID): 33760234; ● Search Scopus @ Elsevier (DOI): 10.1002/mp.14857

(DOI: 10.1002/mp.14857, PubMed: 33760234) Natsumi Kimoto, Hayashi Hiroaki, Takmumi Asakawa, Cheonghae Lee, Takashi Asahara, Tatsuya Maeda, Sota Goto, Yuki Kanazawa, Akitoshi Katsumata, Shuichiro Yamamoto and Masahiro Okada :
Effective atomic number image determination with an energy-resolving photon-counting detector using polychromatic X-ray attenuation by correcting for the beam hardening effect and detector response,
Applied Radiation and Isotopes, Vol.170, 109617, 2021.

(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.apradiso.2021.109617
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1016/j.apradiso.2021.109617

(DOI: 10.1016/j.apradiso.2021.109617) Takashi Asahara, Hiroaki Hayashi, Sota Goto, Natsumi Kimoto, Kazuki Takegami, Tatsuya Maeda, Yuki Kanazawa, Tohru Okazaki and Takuya Hashizume :
Evaluation of calibration factor of OSLD toward eye lens exposure dose measurement of medical staff during IVR,
Journal of Applied Clinical Medical Physics, Vol.in press, 2020.

(徳島大学機関リポジトリ): ● Metadata: 115925
(出版サイトへのリンク): ● Publication site (DOI): 10.1002/acm2.13042
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1002/acm2.13042

(徳島大学機関リポジトリ: 115925, DOI: 10.1002/acm2.13042) 井上雄介, 榎泰之, 鈴木正行, 金澤裕樹, 川島博子 :
乳腺ダイナミックMRIにおける腫瘍辺縁部と腫瘍中心部の時間信号曲線の違いについてー病理組織との対比ー,
日本がん健診・診断学会誌, Vol.28, No.1, 1-6, 2020年. Sota Goto, Hiroaki Hayashi, Emi Tomita, Takashi Asahara, Natsumi Kimoto, Kazuki Takegami, Takumi Asakawa, Yuki Kanazawa, Tohru Okazaki and Takuya Hashizume :
An idea to reduce angular dependence of dosimeter having a disk-shaped detection region,
Radiation Measurements, Vol.137, 106323, 2020.

(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.radmeas.2020.106323
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1016/j.radmeas.2020.106323

(DOI: 10.1016/j.radmeas.2020.106323) Ikuho Kosaka, Yuki Kanazawa, Kotaro Baba, Hiroaki Hayashi and Masafumi Harada :
Quantitative analysis of vibration waves based on Fourier transform in magnetic resonance elastography,
Radiological Physics and Technology, Vol.13, 268-275, 2020.

(要約): We developed a novel magnetic resonance elastography (MRE) analysis method based on Fourier transform to assess the responsive characteristics for different tissue stiffness and degree of transmission of the vibration wave emanating from a passive driver during MRE. A phantom tissue study was conducted with an MRE sequence and vibration wave system using a clinical MR scanner. The phantom tissue consisted of two layers of agar: 0.75 wt% and 1.0 wt%. Phase-unwrapped images derived from acquired MRE phase images were used to generate a phase profile curve, with a line plotted for the phase-unwrapped images. Fourier transform was performed, and the peak value of the power spectrum was derived. The damping rate/ratio was calculated using the Hilbert transform of the phase profile. We found that the mean shear stiffness value of 1.0 wt% agar was higher than that of 0.75 wt% agar. The responsive frequency of the 0.75 wt% agar layer showed a wider range and the damping rate of the signal showed a higher value than the respective values of the 1.0 wt% agar layer. In conclusion, Fourier transform analysis of MRE enabled us to obtain more detailed information of the tissue characteristics and vibration-wave conditions.
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-020-00579-y
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 32766948; ● Search Scopus @ Elsevier (PMID): 32766948; ● Search Scopus @ Elsevier (DOI): 10.1007/s12194-020-00579-y

(DOI: 10.1007/s12194-020-00579-y, PubMed: 32766948) Maki Ohtomo, Masafumi Harada, Takashi Abe, Yuki Matsumoto, Yumi Abe, Yuki Kanazawa, Mitsuharu Miyoshi, Hiroyuki Kabasawa and Yoshitake Takahashi :
Reproducibility and Variability of Quantitative Cerebral Blood Flow Measured by Multi-delay 3D Arterial Spin Labeling According to Sex and Menstrual Cycle,
The Journal of Medical Investigation : JMI, Vol.67, No.3.4, 321-327, 2020.

(要約): Purpose : To determine the reproducibility of corrected quantitative cerebral blood flow (qCBF) through measurement of transit flow time using multi-delay three-dimensional pseudo-continuous arterial spin labeling (pCASL) in healthy men and women and to evaluate the differences in qCBF between not only men and women, but also the follicular and luteal phases of the women's menstrual cycle. Methods : The participants were 16 healthy volunteers (8 men and 8 women ; mean age, 25.3 years). Two MRI were conducted for all participants ; female participants were conducted in the follicular and luteal phases. The reproducibility of qCBF values was evaluated by the intraclass correlation coefficient (ICC) and differences between the two groups were estimated by voxel-based morphometry (VBM) analysis. Results : The qCBF values were lower in men than in women, and those in females were significantly different between the follicular and luteal phases (P < 0.05). In VBM analysis, the qCBF values of the lower frontal lobes were significantly higher in women than in men (P < 0.05). The qCBF values of the frontal pole were significantly higher in the follicular phase than in the luteal phase (P < 0.01). Conclusion : Multi-delay pCASL can reveal physiological and sex differences in cerebral perfusion. J. Med. Invest. 67 : 321-327, August, 2020.
(キーワード): 脳神経画像 / 動脈スピン標識法 / 脳血流量 (cerebral blood flow) / 三次元定位ROIテンプレート / 男女差
(徳島大学機関リポジトリ): ● Metadata: 115293
(出版サイトへのリンク): ● Publication site (DOI): 10.2152/jmi.67.321
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 33148909; ● Search Scopus @ Elsevier (PMID): 33148909; ● Search Scopus @ Elsevier (DOI): 10.2152/jmi.67.321

(徳島大学機関リポジトリ: 115293, DOI: 10.2152/jmi.67.321, PubMed: 33148909) Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi, Takashi Abe, Yuki Matsumoto and Yasushi Takagi :
Characterization of Brain Tumors using Amide Proton and Nuclear Overhauser Effect at 3 Tesla MR Scanner,
Proceedings of the 28th Virtual Conference of ISMRM, No.1697, 2020. Yuki Kanazawa, Masafumi Harada, Tosiaki Miyati, Takashi Abe, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Yasuhisa Kanematsu and Yasushi Takagi :
Chemical Exchange Saturation Transfer Imaging for Atherosclerotic Plaques,
Proceedings of 28th Virtual Meeting of ISMRM, No.2128, 2020. Kazuki Takegami, Hiroaki Hayashi, Takashi Asahara, Sota Goto, Emi Tomita, Natsumi Kimoto, Yuki Kanazawa and Shohei Kudomi :
Dose calibration factor of an OSL dosimeter during CT examination to measure exposure dose of patients taking into consideration proper X-ray quality,
European Congress of Radiology (EPOS), No.C-01393, 2020.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2020/C-01393
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2020/C-01393

(DOI: 10.26044/ecr2020/C-01393) Yugo Wada, Yuki Kanazawa, Masafumi Harada, Naoki Maeda, Yuki Matsumoto, Takashi Abe, Hiroaki Hayashi, Mitsuharu Miyoshi and Carl Michael :
Multi-components analysis of brain using ultrashort echo time magnetic resonance imaging,
European Congress of Radiology (EPOS), No.C-08766, 2020.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2020/C-08766
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2020/C-08766

(DOI: 10.26044/ecr2020/C-08766) Naoki Maeda, Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Yuki Matsumoto, Takashi Abe, Hiroaki Hayashi, Masaharu Ono and Yoshitaka Bito :
Multicomponent T1 Relaxometry Analysis using Quantitative Parameter Mapping Magnetic Resonance Imaging,
European Congress of Radiology (EPOS), No.C-8678, 2020.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2020/C-08767
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2020/C-08767

(DOI: 10.26044/ecr2020/C-08767) Yuki Kanazawa, Chiba Daiki, Masafumi Harada, Miyati Tosiaki, Miyoshi Mitsuharu, Hiroaki Hayashi, Yuki Matsumoto, Takashi Abe and Akihiro Haga :
Thermal sensitive pH imaging using CEST,
Proceedings of the 27th Annual Meeting of ISMRM, No.3991, 2019. Yuki Kanazawa, Masafumi Harada, Taniguchi Yo, Hiroaki Hayashi, Takashi Abe, Maki Ohtomo, Yuki Matsumoto, Ono Masafumi, Bito Yoshitaka and Akihiro Haga :
Myelin imaging derived from quantitative parameter mapping,
Proceedings of the 27th Annual Meeting of ISMRM, No.3313, 2019. Yuki Kanazawa, Yuki Matsumoto, Masafumi Harada, Hiroaki Hayashi, Tsuyoshi Matsuda and Hideki Otsuka :
Appropriate echo time selection for quantitative susceptibility mapping.,
Radiological Physics and Technology, Vol.12, 185-193, 2019.

(要約): The purpose of our study was to clarify the dependence of quantitative susceptibility mapping (QSM) on echo time (TE). We constructed a phantom consisting of six tubes; three tubes were filled with different concentrations (0.5, 1.0, and 2.5 mM) of gadopentetate dimeglumine (Gd-DTPA), and three were filled with different concentrations (100, 200, and 350 mg/mL) of calcium hydroxyapatite. Real and imaginary images from multi-echo spoiled gradient-echo data (12 echoes) were acquired. We then used four datasets with three serial echoes. The QSM procedure consists of four steps: field map estimation, phase unwrapping, background removal, and dipole inversion. For each sample, we compared the measured mean susceptibility value with the theoretical susceptibility value and conducted a linear regression analysis. Accordingly, the relationship between the measured susceptibility and concentration of Gd-DTPA was shown to agree well with the theoretical values (TEs = 16.4, 20.8, and 25.2 ms; slope = 0.24, R = 1.00). Furthermore, the relationship between the measured susceptibility and concentration of hydroxyapatite also showed good linearity (TEs = 16.4, 20.8, and 25.2 ms; slope = - 0.00121, R = 1.00). In conclusion, the optimization of the TE in QSM makes it possible to obtain more detailed information regarding the susceptibility of biomaterials.
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-019-00513-x
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 30980255; ● Summary page in Scopus @ Elsevier: 2-s2.0-85064249322

(DOI: 10.1007/s12194-019-00513-x, PubMed: 30980255, Elsevier: Scopus) Takashi Abe, Yuki Matsumoto, Yuki Kanazawa, Yoichi Otomi, Maki Otomo, Moriaki Yamanaka, Mihoko Kondo, Saya Matsuzaki, Ariunbold Gankhuyag, Enkhamgalan Dolgorsuren, Oyundari Gonchigsuren and Masafumi Harada :
Comparing neural networks for synthesizing FLAIR images from T1WI and T2WI,
Proceedings of the 27th Annual Meeting of ISMRM, No.240, 2019. Tohru Okazaki, Hiroaki Hayashi, Sota Goto, Takashi Asahara, Emi Tomita, Yuki Kanazawa, Takuya Hashizume, V Cruz and H W Cheng :
Determining the difference of calibration factors in diagnostic X-rays and mono-energetic X-rays of the small type OSL dosimeter for a more precise dose evaluation in diagnostic X-ray examinations,
European Congress of Radiology (EPOS), No.C-0212, 14, 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2019/C-0212
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2019/C-0212

(DOI: 10.26044/ecr2019/C-0212) Yoshiki Mihara, Hiroaki Hayashi, Takumi Uehara, Emi Tomita, Sota Goto, Keiji Tada, Yuki Kanazawa, Tohru Okazaki and Takuya Hashizume :
Where do the scattering X-rays to eye lens exposure come from during neonatal cardiac CT examination?,
European Congress of Radiology (EPOS), No.C-1825, 26, 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2019/C-1825
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2019/C-1825

(DOI: 10.26044/ecr2019/C-1825) Tohru Okazaki, Hiroaki Hayashi, Yoshiki Mihara, Takashi Asahara, Natsumi Kimoto, Yuki Kanazawa, Kosaku Higashino, Kazuta Yamashita, Sumi Yokoyama, Kazuki Takegami, Takuya Hashizume, Vergil LE Cruz and Ikuo Kobayashi :
Applicability of a Practical Calibration for the Small-type OSL Dosimeter for Measuring Doses from Direct X-rays and Penetrating X-rays Affected by Scattered Radiation,
Progress in Nuclear Science and Technology, Vol.6, 22-25, 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.15669/pnst.6.22
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.15669/pnst.6.22

(DOI: 10.15669/pnst.6.22) Hiroaki Hayashi, Emi Tomita, Sota Goto, Natsumi Kimoto, Keiji Tada, Ryosuke Kasai, Yuki Kanazawa, Yoshiki Mihara, Takashi Asahara, Tohru Okazaki, Takuya Hashizume and Vergil LE Cruz :
Direct Dose Measurement of Patients during Pediatric Computed Tomography Examination,
Progress in Nuclear Science and Technology, Vol.6, 18-21, 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.15669/pnst.6.18
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.15669/pnst.6.18

(DOI: 10.15669/pnst.6.18) Vergil LE Cruz, Tohru Okazaki, Hiroaki Hayashi, Yoshiki Mihara, Takashi Asahara, Natsumi Kimoto, Hiroki Okino, Yuki Kanazawa, Takuya Hashizume and Ikuo Kobayashi :
Energy and Angular Dependence of the Small-Type OSL Dosimeter in Nuclear Medicine Regions using Monte Carlo Simulation,
Progress in Nuclear Science and Technology, Vol.6, 34-38, 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.15669/pnst.6.34
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.15669/pnst.6.34

(DOI: 10.15669/pnst.6.34) Takashi Asahara, Hiroaki Hayashi, Emi Tomita, Kanako Sakuragawa, Hiroshi Saegusa, Yasufumi Shitakubo, Hitoshi Ikushima, Yuki Kanazawa, Yoshiki Mihara, Yoshinori Miyahara, Tohru Okazaki, Takuya Hashizume and Vergil LE Cruz :
Development of Novel Rectum Dosimeter using OSL sheet with the aim of Direct Dose Measurement of Organ Dose during Brachytherapy,
Progress in Nuclear Science and Technology, Vol.6, 30-33, 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.15669/pnst.6.30
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.15669/pnst.6.30

(DOI: 10.15669/pnst.6.30) Emi Tomita, Hiroaki Hayashi, Takashi Asahara, Kanako Sakuragawa, Yasufumi Shitakubo, Hiroshi Saegusa, Hitoshi Ikushima, Yuki Kanazawa, Sota Goto, Tohru Okazaki, Takuya Hashizume and Vergil LE Cruz :
Direct Radiation Dose Measurement of Rectum during High-Dose-Rate ¹⁹²Ir Brachytherapy for Cervical Cancer Treatment,
Progress in Nuclear Science and Technology, Vol.6, 39-42, 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.15669/pnst.6.39
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.15669/pnst.6.39

(DOI: 10.15669/pnst.6.39) Enkh-Amgalan Dolgorsuren, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Maki Otomo, Yuki Matsumoto, Yoshifumi Mizobuchi and Kohhei Nakajima :
Correlation and Characteristics of Intravoxel Incoherent Motion and Arterial Spin Labeling Techniques Versus Multiple Parameters Obtained on Dynamic Susceptibility Contrast Perfusion MRI for Brain Tumors.,
The Journal of Medical Investigation : JMI, Vol.66, No.3.4, 308-313, 2019.

(要約): Purpose : To compare data on brain tumors derived from intravoxel incoherent motion (IVIM) and arterial spin labeling (ASL) imaging with multiple parameters obtained on dynamic susceptibility contrast (DSC) perfusion MRI and to clarify the characteristics of IVIM and ASL perfusion data from the viewpoint of cerebral blood flow (CBF) analysis. Methods : ASL-CBF and IVIM techniques as well as DSC examination were performed in 24 patients with brain tumors. The IVIM data were analyzed with the two models. The relative blood flow (rBF), relative blood volume (rBV) corrected relative blood volume (crBV), mean transit time (MTT), and leakage coefficient (K2) were obtained from the DSC MRI data. Results : The ASL-CBF had the same tendency as the perfusion parameters derived from the DSC data, but the permeability from the vessels had less of an effect on the ASL-CBF. The diffusion coefficient of the fast component on IVIM contained more information on permeability than the f value. Conclusion : ASL-CBF is more suitable for the evaluation of perfusion in brain tumors than IVIM parameters. ASL-CBF and IVIM techniques should be carefully selected and the biological significance of each parameter should be understood for the correct comprehension of the pathological status of brain tumors. J. Med. Invest. 66 : 308-313, August, 2019.
(キーワード): Intravoxel incoherent motion / arterial spin labeling / brain tumor / dynamic susceptibility contrast perfusion / Spin Labels
(徳島大学機関リポジトリ): ● Metadata: 113793
(出版サイトへのリンク): ● Publication site (DOI): 10.2152/jmi.66.308
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 31656295; ● Search Scopus @ Elsevier (PMID): 31656295; ● Search Scopus @ Elsevier (DOI): 10.2152/jmi.66.308

(徳島大学機関リポジトリ: 113793, DOI: 10.2152/jmi.66.308, PubMed: 31656295) Natsumi Kimoto, Hiroaki Hayashi, Takumi Asakawa, takashi Asahara, Maeda Tatsuya, Yuki Kanazawa, Akitoshi Katsumata, Shuichiro Yamamoto and Okada Masahiro :
Feasibility study of photon counting detector for producing effective atomic number image,
Proceedings of IEEE(MIC), 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.1109/NSS/MIC42101.2019.9059919
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-85083575403

(DOI: 10.1109/NSS/MIC42101.2019.9059919, Elsevier: Scopus) Takashi Asahara, Hiroaki Hayashi, Sota Goto, Emi Tomita, Natsumi Kimoto, Yoshiki Mihara, Takumi Asakawa, Yuki Kanazawa, Akitoshi Katsumata, Kosaku Higashino, Kazuta Yamashita, Tohru Okazaki and Takuya Hashizume :
Exposure dose measurement during diagnostic pediatric X-ray examination using an optically stimulated luminescence (OSL) dosimeter based on precise dose calibration taking into consideration variation of X-ray spectra,
Radiation Measurements, Vol.119, 209-219, 2018.

(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.radmeas.2018.10.007
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1016/j.radmeas.2018.10.007

(DOI: 10.1016/j.radmeas.2018.10.007) Natsumi Kimoto, Hiroaki Hayashi, Takashi Asahara, Emi Tomita, Sota Goto, Yuki Kanazawa, Shuichiro Yamamoto, Masahiro Okada and Masaki Yamasaki :
Reproduction of response functions of a multi-pixel-type energy-resolved photon counting detector while taking into consideration interaction of X-rays, charge sharing and energy resolution,
Proceedings of IEEE(MIC), 4, 2018.

(出版サイトへのリンク): ● Publication site (DOI): 10.1109/NSSMIC.2018.8824417
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-85073110282

(DOI: 10.1109/NSSMIC.2018.8824417, Elsevier: Scopus) Yuki Kanazawa, Kotaro Baba, Tosiaki Miyati, Masafumi Harada, Hiroaki Hayashi, Ikuho Kosaka, Mitsuharu Miyoshi, Michael Carl and Yuki Matsumoto :
Does the amount of signal change depend on calcium concentration in lipid-rich core plaque?,
Proceedings of the 26th Annual Meeting of ISMRM, No.3473, 2018. Yuki Kanazawa, Toshiaki Sasaki, Hiroaki Hayashi, Kotaro Baba, Ikuho Kosaka, Yuki Matsumoto, Mitsuharu Miyoshi and Masafumi Harada :
T1 dependency of magnetization transfer effect in human brain,
Proceedings of the 26th Annual Meeting of ISMRM, No.3179, 2018. Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi, Ikuho Kosaka, Kotaro Baba, Hiroaki Hayashi and Yuki Matsumoto :
Nuclear Overhauser enhancement effect of low B1 power CEST RF in human brain at 3.0 T,
Proceedings of the 26th Annual Meeting of ISMRM, No.5117, 2018. Yuki Kanazawa, Yasutaka Fushimi, Naotaka Sakashita, Tomohisa Okada, Yoshiki Arakawa and Mitsue Miyazaki :
B₁ Power Optimization for Chemical Exchange Saturation Transfer Imaging: A Phantom Study Using Egg White for Amide Proton Transfer Imaging Applications in the Human Brain,
Magnetic Resonance in Medical Sciences, Vol.17, No.1, 86-94, 2018.

(要約): The chemical exchange saturation transfer (CEST) effect on an egg white suspension was investigated for optimization of magnetization transfer (MT) power (B1,rms) and pH dependency with addition of lactic acid. Applying a higher magnetization transfer (MT) pulse, B1,rms, Z-spectrum shows higher asymmetry and the MTRasym signal increases to around 1-3.5 ppm, indicating a higher CEST effect. Amide proton (-NH) transfer (APT) at 3.5 ppm shows a signal elevation in MTRasym with the application of higher B1,rms power and high pH. In addition, the hydroxyl (-OH) proton signal in MTRasym increases as pH is reduced by lactic acid. In Z-spectrum of B1,rms at 1.0 T and 2.0 T, the dependence on CEST effect of amide (-NH) and hydroxyl (-OH) proton could be observed by using an egg white suspension phantom. The CEST MT power was optimized on the egg white suspension phantom with pH dependency and further confirmed on volunteers. In addition, APT imaging at 3.5 ppm using B1,rms at 1.0 T performed on two human brains with different pathophysiological conditions indicated appropriate ATP effect.
(キーワード): Chemical exchange saturation transfer (CEST) / B0 correction / B1 power / pH dependency / egg white / Amide Proton Transfer (APT) / APT effect on human brain
(徳島大学機関リポジトリ): ● Metadata: 116225
(出版サイトへのリンク): ● Publication site (DOI): 10.2463/mrms.tn.2016-0069
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 28566586; ● Search Scopus @ Elsevier (PMID): 28566586; ● Search Scopus @ Elsevier (DOI): 10.2463/mrms.tn.2016-0069

(徳島大学機関リポジトリ: 116225, DOI: 10.2463/mrms.tn.2016-0069, PubMed: 28566586) Natsuki Ikemitsu, Yuki Kanazawa, Yuki Matsumoto, Hiroaki Hayashi, Toshiaki Sasaki, Mitsuharu Miyoshi and Masafumi Harada :
Development of correction for signal-to-noise ratio using a T2* with improved Phase method,
Journal of Computer Assisted Tomography, Vol.42, No.1, 117-123, 2018.

(要約): This study aims to improve the signal-to-noise ratio (SNR) of the phase image focusing T2 and to develop an improved phase (iPhase) image acquired high SNR. The iPhase images of phantom and brain were acquired with multi-echo spoiled gradient-echo. The phantom component was a gadopentetate dimeglumine (Gd-DTPA) solution made of different concentrations (0.1, 0.5, and 1 wt%) and Gd-DTPA (0.1, 0.5, and 1 wt%) with agar (1.0 wt%). We applied the iPhase image to susceptibility weighed image (SWI) and evaluated SNR of SWI. In phantom study, SNRs of conventional SWI at each sample were 19.8, 15.7, 7.4, 20.0, 17.4, and 27.3, respectively. Signal-to-noise ratios of SWI derived from iPhase method were 29.5, 33.7, 21.7, 28.5, 24.3, and 14.7, respectively. Then, the SNR showed an improvement of 196% at maximum (for the Gd-DTPA 1 wt% sample). In healthy volunteer study, SWI derived from iPhase method had the good contrast between white matter and gray matter. The iPhase image was able to improve the phase SNR. Moreover, iPhase method makes it possible to obtain a high SNR image when applying to SWI.
(出版サイトへのリンク): ● Publication site (DOI): 10.1097/RCT.0000000000000644
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 28708721; ● Search Scopus @ Elsevier (PMID): 28708721; ● Search Scopus @ Elsevier (DOI): 10.1097/RCT.0000000000000644

(DOI: 10.1097/RCT.0000000000000644, PubMed: 28708721) Takashi Asahara, Hiroaki Hayashi, Emi Tomita, Sota Goto, Natsumi Kimoto, Kenji Yamada, Sumi Yokoyama, Yuki Kanazawa and Tohru Okazaki :
Phantom study using an OSL dosimeter with the aim of accurate measurement of eye lens dose exposure of operator during transfemoral cardiac catheterization using fluoroscopic examination,
European Congress of Radiology, Vol.EPOS, No.C-0044, 2018.

(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2018/C-0044
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2018/C-0044

(DOI: 10.1594/ecr2018/C-0044) Yuki Kanazawa, Tetsuya Yamada, Aki Kido, Koji Fujimoto, Kyoko Takakura, Hiroaki Hayashi, Yasutaka Fushimi, Satoshi Kozawa, Koji Koizumi, Makiko Okuni, Naomi Ueda and Kaori Togashi :
Internal evaluation of impregnation treatment of waterlogged wood; relation between concentration of internal materials and relaxation time using magnetic resonance imaging,
Magnetic Resonance Imaging, Vol.38, 196-201, 2017.

(キーワード): Conservation science / Repair operation / Impregnation treatment / Waterlogged wood / Magnetic resonance imaging (MRI)
(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.mri.2017.01.010
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 28095302; ● Search Scopus @ Elsevier (PMID): 28095302; ● Search Scopus @ Elsevier (DOI): 10.1016/j.mri.2017.01.010

(DOI: 10.1016/j.mri.2017.01.010, PubMed: 28095302) Mitsuharu Miyoshi, Masafumi Harada, Yuki Kanazawa and Hiroyuki Kabasawa :
CEST and Binding Water MT Separation in Brain Tumor by Multi Pool Model CEST Peak Extraction Method,
Proceedings of the 25th Annual Meeting of ISMRM, 4242, 2017. Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Toshiaki Sasaki and Natsuki Ikemitsu :
Baseline of Chemical Exchange Saturation Transfer Imaging for Brain,
Proceedings of the 25th Annual Meeting of ISMRM, 4646, 2017. Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Toshiaki Sasaki, Natsuki Ikemitsu and Michael Carl :
Dura Mater imaging with UTE T2* Mapping,
Proceedings of the 25th Annual Meeting of ISMRM, 4682, 2017. Natsumi Kimoto, Hiroaki Hayashi, Takashi Asahara, Yoshiki Mihara, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki and Masahiro Okada :
Precise material identification method based on a photon counting technique with correction of the beam hardening effect in X-ray spectra,
Applied Radiation and Isotopes, Vol.124, 16-26, 2017.

(要約): The aim of our study is to develop a novel material identification method based on a photon counting technique, in which the incident and penetrating X-ray spectra are analyzed. Dividing a 40-kV X-ray spectra into two energy regions, the corresponding linear attenuation coefficients are derived. We can identify the materials precisely using the relationship between atomic number and linear attenuation coefficient through the correction of the beam hardening effect of the X-ray spectra.
(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.apradiso.2017.01.049
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 28314161; ● Summary page in Scopus @ Elsevier: 2-s2.0-85015006820

(DOI: 10.1016/j.apradiso.2017.01.049, PubMed: 28314161, Elsevier: Scopus) Kazuki Takegami, Hiroaki Hayashi, Kenji Yamada, Yoshiki Mihara, Natsumi Kimoto, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Fumio Hayashi, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Entrance surface dose measurements using a small OSL dosimeter with a computed tomography scanner having 320 rows of detectors,
Radiological Physics and Technology, Vol.10, No.1, 49-59, 2017.

(要約): Entrance surface dose (ESD) measurements are important in X-ray computed tomography (CT) for examination, but in clinical settings it is difficult to measure ESDs because of a lack of suitable dosimeters. We focus on the capability of a small optically stimulated luminescence (OSL) dosimeter. The aim of this study is to propose a practical method for using an OSL dosimeter to measure the ESD when performing a CT examination. The small OSL dosimeter has an outer width of 10 mm; it is assumed that a partial dose may be measured because the slice thickness and helical pitch can be set to various values. To verify our method, we used a CT scanner having 320 rows of detectors and checked the consistencies of the ESDs measured using OSL dosimeters by comparing them with those measured using Gafchromic™ films. The films were calibrated using an ionization chamber on the basis of half-value layer estimation. On the other hand, the OSL dosimeter was appropriately calibrated using a practical calibration curve previously proposed by our group. The ESDs measured using the OSL dosimeters were in good agreement with the reference ESDs from the Gafchromic™ films. Using these data, we also estimated the uncertainty of ESDs measured with small OSL dosimeters. We concluded that a small OSL dosimeter can be considered suitable for measuring the ESD with an uncertainty of 30 % during CT examinations in which pitch factors below 1.000 are applied.
(徳島大学機関リポジトリ): ● Metadata: 110814
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-016-0366-1
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 27341805; ● Search Scopus @ Elsevier (PMID): 27341805; ● Search Scopus @ Elsevier (DOI): 10.1007/s12194-016-0366-1

(徳島大学機関リポジトリ: 110814, DOI: 10.1007/s12194-016-0366-1, PubMed: 27341805) Yoshiki Mihara, Hiroaki Hayashi, Kenji Yamada, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Ryosuke Kasai, Tohru Okazaki and Takuya Hashizume :
Basic study for internal dose evaluation during CT examination by means of small-type OSL dosimeter,
European Congress of Radiology, C-0005-1-C-0005-22, 2017.

(要約): [Aims and objectives] We plan to manage the patient dose exposure during computed tomography (CT) examination using a small-type OSL dosimeter. The OSL dosimeter can measure entrance skin dose (ESD) directly, but the internal dose can't be measured. The aim of this study is to clarify the relationship between the ESD and internal dose during the CT examination. [Methods and materials] We constructed an abdominal phantom, in which OSL dosimeters can be implanted in, and used this phantom to measure external and internal doses during CT examination. The typical irradiation conditions were as follow, 64 rows of detectors, 120 kV, 600 mA, PF (pitch factor) = 1.484 in helical scan mode. Additionally, we analyzed the contribution of X-rays, which were generated from different angles to the dosimeter; namely, angular dependences of 0-360 degrees at 45 degree intervals were evaluated experimentally. [Results] The ESDs and internal doses showed similar values, however the deviations between them were completely different; maximum deviation of ESD was found to be 30% and that of internal dose was at the most 5%. The deviation in ESDs is explained by the phenomenon in which some dosimeters were irradiated by direct X-ray and others were not. However, the small deviation between internal doses was explained by the phenomenon in which dosimeters were mainly irradiated by scattered X-rays. [Conclusion] In this study, we analyzed the relationship between ESD and internal dose for direct dose measurement of patient dose undergoing CT examination. The ESDs show relatively large fluctuations, on the other hand, the internal doses show small deviations.
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2017/C-0005
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2017/C-0005

(DOI: 10.1594/ecr2017/C-0005) Hiroaki Hayashi, Yoshiki Mihara, Natsumi Kimoto, Takashi Asahara, Kenji Yamada, Yuki Kanazawa, Masafumi Harada, Tohru Okazaki and Takuya Hashizume :
Preliminary study for exposure dose measurement of people assisting during a pediatric X-ray procedure by means of a small-type OSL dosimeter,
European Congress of Radiology, C-0034-1-C-0034-19, 2017.

(要約): [Aims and objectives] During a pediatric X-ray procedure, medical staff or other people such as parents may assist to hold children during the X-ray examination. In this situation, these assistances are exposed by scattered X-rays, but there are no precise data concerning exposure doses. The aim of this study is to measure exposure dose of people assisting during the X-ray procedure. [Methods and materials] We used small-type OSL dosimeter (Landauer), which was sufficiently initialized. The detection limit of our system was estimated to be 0.5 micro-Gy. The OSL dosimeter was attached outside the lead protector which was worn by the assistant. In order to reduce contamination from background X- and/or gamma-rays, the exposed dosimeters were analyzed within 12 hours. The X-ray diagnostic system consisted of X-ray equipment and flat-panel detector which has auto-exposure control. The typical irradiation condition was SID=1.1 m, 3.2 mAs, and 53 kV. [Results] The exposure doses of assistances in the position outside the lead protector were approximately 3 micro-Gy. We measured 5 cases, in which patient's ages were 7 months to 1 year 6 months. Patient age showed no significant differences in exposure doses. [Conclusion] For the first time, using the small-type OSL dosimeter, we measured exposure dose of people assisting during a pediatric X-ray examination in a position outside the lead protector. The measured value was extremely low. Our actual data supports the justification of the situation in which someone should hold a child during an X-ray procedure.
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2017/C-0034
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2017/C-0034

(DOI: 10.1594/ecr2017/C-0034) Natsuki Ikemitsu, Yuki Kanazawa, Yuki Matsumoto, Hiroaki Hayashi, Takatoshi Usuda, Toshiaki Sasaki, Mitsuharu Miyoshi and Masafumi Harada :
An improvement of signal-to-noise ratio for phase image,
European Congress of Radiology (EPOS), C-0803, 2017.

(徳島大学機関リポジトリ): ● Metadata: 111042
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2017/C-0803
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2017/C-0803

(徳島大学機関リポジトリ: 111042, DOI: 10.1594/ecr2017/C-0803) Toshiaki Sasaki, Yuki Kanazawa, Yuki Matsumoto, Hiroaki Hayashi, Natsuki Ikemitsu, Takatoshi Usuda, Mitsuharu Miyoshi and Masafumi Harada :
T1 dependence of magnetization transfer effect for macromolecules,
European Congress of Radiology (EPOS), C-0827, 2017.

(要約): Purpose: To assess the relationship between T1 and magnetization transfer (MT) effect on macromolecules, we determined T1 map derived from variable flip angle (VFA) method with MT pulse. Materials and Methods: On a 3.0 T magnetic resonance (MR) system, we performed a phantom study using spoiled gradient-echo sequences; TR, 600 ms; TE, 5.8 ms; FA, 5, 20, 40, 60, and 90 degrees; without and with MT pulse (offset frequency, 800 ,1200 , and 1600 Hz). The phantom components were six samples; water and polyethylene glycol (PEG) solutions at different concentrations (10, 20, 30, 40, and 50 wt%). We calculated T1 maps from image datasets without and with MT pulse. Then, the MT ratio (MTR) maps were calculated from each FA image. Results: The mean T1 range without MT pulse for each sample was from 1200 to 2039 ms. The mean T1 ranges with MT pulse of each sample were from 1322 to 1886 at 800 Hz; from 1310 to 1926 ms at 1200 Hz; from 1300 to 1909 ms at 1600 Hz. The MTR of each sample showed the highest value at FA 5 degrees and offset 800 Hz. The mean MTR values of each sample were 6.54 ± 2.78, 3.94 ± 1.92, 2.50 ± 1.67, 1.96 ± 1.33, 1.44 ± 1.15, and 1.78 ± 1.53%. Conclusion: Determination of T1 with MT pulse makes it possible to obtain more detailed information of macromolecules.
(徳島大学機関リポジトリ): ● Metadata: 111041
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2017/C-0827
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2017/C-0827

(徳島大学機関リポジトリ: 111041, DOI: 10.1594/ecr2017/C-0827) Natsumi Kimoto, Hiroaki Hayashi, Asahara Takashi, Yuki Kanazawa, Yamakawa Tsutomu, Yamamoto Shuichiro, Yamasaki Masashi and Okada Masahiro :
Development of a novel method based on a photon counting technique with the aim of precise material identification in clinical X-ray diagnosis,
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 2017.

(出版サイトへのリンク): ● Publication site (DOI): 10.1117/12.2253564
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1117/12.2253564

(DOI: 10.1117/12.2253564) Hiroaki Hayashi, Takashi Asahara, Natsumi Kimoto, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki and Masahiro Okada :
Response functions of multi-pixel-type CdTe detector, --- Toward development of precise material identification on diagnostic X-ray images by means of photon counting ---,
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, Vol.10132, 1013236, 2017.

(出版サイトへのリンク): ● Publication site (DOI): 10.1117/12.2251185
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1117/12.2251185

(DOI: 10.1117/12.2251185) Hiroaki Hayashi, Yoshiki Mihara, Yuki Kanazawa, Emi Tomita, Sota Goto, Kazuki Takegami, Tohru Okazaki, Takuya Hashizume and Vergil Estacio Lorenzo Cruz :
Necessity of Direct Dose Measurement during Current X-ray Diagnosis, --- Our Approach Using a Small-type OSL Dosimeter ---,
Medical Research Archives, Vol.5, No.2, 1-20, 2017.

(出版サイトへのリンク): ● Publication site (DOI): 10.18103/mra.v5i2.1030
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.18103/mra.v5i2.1030

(DOI: 10.18103/mra.v5i2.1030) Yuki Kanazawa, Tetsuya Yamada, Aki Kido, Koji Fujimoto, Kyoko Takakura, Hiroaki Hayashi, Yasutaka Fushimi, Satoshi Kozawa, Koji Koizumi, Makiko Okuni, Naomi Ueda and Kaori Togashi :
Visualization of magnetic transfer effect in polyethylene glycol impregnated waterlogged wood.,
Applied Magnetic Resonance, Vol.48, No.2, 125-134, 2017.

(キーワード): preservative treatment / waterlogged wood / polyethylene glycol impregnation / magnetic resonance image / magnetic transfer
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s00723-016-0850-0
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1007/s00723-016-0850-0

(DOI: 10.1007/s00723-016-0850-0) Kazuki Takegami, Hiroaki Hayashi, Hiroki Okino, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Estimation of identification limit for a small-type OSL dosimeter on the medical images by measurement of X-ray spectra,
Radiological Physics and Technology, Vol.9, No.2, 282-292, 2016.

(要約): Our aim in this study is to derive an identification limit on a dosimeter for not disturbing a medical image when patients wear a small-type optically stimulated luminescence (OSL) dosimeter on their bodies during X-ray diagnostic imaging. For evaluation of the detection limit based on an analysis of X-ray spectra, we propose a new quantitative identification method. We performed experiments for which we used diagnostic X-ray equipment, a soft-tissue-equivalent phantom (1 20 cm), and a CdTe X-ray spectrometer assuming one pixel of the X-ray imaging detector. Then, with the following two experimental settings, corresponding X-ray spectra were measured with 40 120 kVp and 0.5 1000 mAs at a source-to-detector distance of 100 cm: (1) X-rays penetrating a soft-tissue-equivalent phantom with the OSL dosimeter attached directly on the phantom, and (2) X-rays penetrating only the soft-tissue-equivalent phantom. Next, the energy fluence and errors in the fluence were calculated from the spectra. When the energy fluence with errors concerning these two experimental conditions was estimated to be indistinctive, we defined the condition as the OSL dosimeter not being identified on the X-ray image. Based on our analysis, we determined the identification limit of the dosimeter. We then compared our results with those for the general irradiation conditions used in clinics. We found that the OSL dosimeter could not be identified under the irradiation conditions of abdominal and chest radiography, namely, one can apply the OSL dosimeter to measurement of the exposure dose in the irradiation field of X-rays without disturbing medical images.
(徳島大学機関リポジトリ): ● Metadata: 110813
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-016-0362-5
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 27260346; ● Search Scopus @ Elsevier (PMID): 27260346; ● Search Scopus @ Elsevier (DOI): 10.1007/s12194-016-0362-5

(徳島大学機関リポジトリ: 110813, DOI: 10.1007/s12194-016-0362-5, PubMed: 27260346) Yuto Konishi, Yuki Kanazawa, Takatoshi Usuda, Yuki Matsumoto, Hiroaki Hayashi, Tsuyoshi Matsuda, Junji Ueno and Masafumi Harada :
Simple noise reduction for diffusion weighted images,
Radiological Physics and Technology, Vol.9, No.2, 221-226, 2016.

(要約): Our purpose in this study was to reduce the noise in order to improve the SNR of Dw images with high b-value by using two correction schemes. This study was performed with use of phantoms made from water and sucrose at different concentrations, which were 10, 30, and 50 weight percent (wt%). In noise reduction for Dw imaging of the phantoms, we compared two correction schemes that are based on the Rician distribution and the Gaussian distribution. The highest error values for each concentration with use of the Rician distribution scheme were 7.3 % for 10 wt%, 2.4 % for 30 wt%, and 0.1 % for 50 wt%. The highest error values for each concentration with use of the Gaussian distribution scheme were 20.3 % for 10 wt%, 11.6 % for 30 wt%, and 3.4 % for 50 wt%. In Dw imaging, the noise reduction makes it possible to apply the correction scheme of Rician distribution.
(徳島大学機関リポジトリ): ● Metadata: 110815
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-016-0350-9
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 26984734; ● Search Scopus @ Elsevier (PMID): 26984734; ● Search Scopus @ Elsevier (DOI): 10.1007/s12194-016-0350-9

(徳島大学機関リポジトリ: 110815, DOI: 10.1007/s12194-016-0350-9, PubMed: 26984734) Yuki Kanazawa, Yuki Matsumoto, Hiroaki Hayashi, Tsuyoshi Matsuda, Munguu Ganbold and Masafumi Harada :
Simple improvement method of uniformity of MR elastography on liver,
Proceedings of the 24th Annual Meeting of ISMRM, 2972, 2016. Itsumi Maehata, Hiroaki Hayashi, Natsumi Kimoto, Kazuki Takegami, Hiroki Okino, Yuki Kanazawa and Masahide Tominaga :
Practical method for determination of air-kerma by using an ionization chamber toward the construction of secondary X-ray field to be used in clinical examination rooms,
Radiological Physics and Technology, Vol.9, No.2, 193-201, 2016.

(徳島大学機関リポジトリ): ● Metadata: 110812
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-016-0352-7
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1007/s12194-016-0352-7

(徳島大学機関リポジトリ: 110812, DOI: 10.1007/s12194-016-0352-7) Tohru Okazaki, Takuya Hashizume, Hiroaki Hayashi, Kazuki Takegami, Hiroki Okino, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa and Kobayashi Ikuo :
Evaluation of energy dependence of nanoDot optically stimulated luminescence (OSL) dosimeter using characteristic X-ray induced by medical X-ray equipment,
European Congress of Radiology (EPOS), C-0338, 2016.

(徳島大学機関リポジトリ): ● Metadata: 111040
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0338
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0338

(徳島大学機関リポジトリ: 111040, DOI: 10.1594/ecr2016/C-0338) Hiroaki Hayashi, Natsumi Kimoto, Hiroki Okino, Kazuki Takegami, Itsumi Maehata and Yuki Kanazawa :
Development of leaf electroscope to understand ionization for novice practical training,
European Congress of Radiology (EPOS), C-0083, 2016.

(徳島大学機関リポジトリ): ● Metadata: 111033
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0083
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0083

(徳島大学機関リポジトリ: 111033, DOI: 10.1594/ecr2016/C-0083) Hiroki Okino, Hiroaki Hayashi, Kazuki Takegami, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Compact irradiation system for evaluation of basic characteristics of the nanoDot OSL dosimeter toward direct measurement of exposure dose of patients,
European Congress of Radiology (EPOS), C-0024, 2016.

(徳島大学機関リポジトリ): ● Metadata: 111030
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0024
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0024

(徳島大学機関リポジトリ: 111030, DOI: 10.1594/ecr2016/C-0024) Natsumi Kimoto, Hiroaki Hayashi, Hiroki Okino, Kazuki Takegami, Itsumi Maehata, Yuki Kanazawa, Tsutomu Yamakawa and Shuichiro Yamamoto :
Fabrication and analysis of phantoms providing the equal-image-density for basic experiment of next-generation-type X-ray diagnosis,
European Congress of Radiology (EPOS), C-0012, 2016.

(徳島大学機関リポジトリ): ● Metadata: 111026
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0012
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0012

(徳島大学機関リポジトリ: 111026, DOI: 10.1594/ecr2016/C-0012) Kazuki Takegami, Hiroaki Hayashi, Hiroki Okino, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Proposal of quantitative identification method of a small-type OSL dosimeter: Verification that the dosimeter is not detected in the medical image,
European Congress of Radiology (EPOS), C-0010, 2016.

(徳島大学機関リポジトリ): ● Metadata: 111025
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0010
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0010

(徳島大学機関リポジトリ: 111025, DOI: 10.1594/ecr2016/C-0010) Itsumi Maehata, Hiroaki Hayashi, Natsumi Kimoto, Hiroki Okino, Kazuki Takegami and Yuki Kanazawa :
Precise determination of the scattered X-ray contamination rate using diagnostic X-ray equipment for the construction of the secondary X-ray field,
European Congress of Radiology (EPOS), C-0007, 2016.

(徳島大学機関リポジトリ): ● Metadata: 111023
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0007
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0007

(徳島大学機関リポジトリ: 111023, DOI: 10.1594/ecr2016/C-0007) Hiroaki Hayashi, Hiroki Okino, Kazuki Takegami, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tsutomu Yamakawa and Shuichiro Yamamoto :
Experimental evaluation of response functions of a CdTe detector in the diagnostic region with the aim of carrying out a basic experiment concerning a next generation photon counting system,
European Congress of Radiology (EPOS), C-0006, 2016.

(徳島大学機関リポジトリ): ● Metadata: 111022
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0006
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0006

(徳島大学機関リポジトリ: 111022, DOI: 10.1594/ecr2016/C-0006) Kazuki Takegami, Hiroaki Hayashi, Hiroki Okino, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment,
Radiological Physics and Technology, Vol.9, No.1, 99-108, 2016.

(要約): For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region.
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-015-0339-9
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-84955746521

(DOI: 10.1007/s12194-015-0339-9, Elsevier: Scopus) Yuto Konishi, Yuki Kanazawa, Takatoshi Usuda, Yuki Matsumoto, Hiroaki Hayashi, Tsuyoshi Matsuda and Masafumi Harada :
Comparison with statistical analysis of signal correction in diffusion weighted MR image,
European Congress of Radiology (EPOS), C-0291, 2016.

(徳島大学機関リポジトリ): ● Metadata: 111021
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0291
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0291

(徳島大学機関リポジトリ: 111021, DOI: 10.1594/ecr2016/C-0291) Yuki Kanazawa, Yuto Konishi, Takatoshi Usuda, Yuki Matsumoto, Hiroaki Hayashi, Tsuyoshi Matsuda and Masafumi Harada :
Noise estimation for diffusion weighted MR image,
European Congress of Radiology (EPOS), C-0591, 2016.

(徳島大学機関リポジトリ): ● Metadata: 110990
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0591
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0591

(徳島大学機関リポジトリ: 110990, DOI: 10.1594/ecr2016/C-0591) Yuki Kanazawa, Hiroaki Hayashi and Masafumi Harada :
Clinical Approach of T1-mapping for Hemodynamic Analysis,
Medical Imaging and Information Sciences, Vol.32, No.4, xxvi-xxix, 2015.

(出版サイトへのリンク): ● Publication site (DOI): 10.11318/mii.32.xxvi
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.11318/mii.32.xxvi

(DOI: 10.11318/mii.32.xxvi) Kazuki Takegami, Hiroaki Hayashi, Hiroki Okino, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tohru Okazaki and Ikuo Kobayashi :
Practical calibration curve of small-type optically stimulated luminescence (OSL) dosimeter for evaluation of entrance-skin dose in the diagnostic X-ray region,
Radiological Physics and Technology, Vol.8, No.2, 286-294, 2015.

(要約): For X-ray diagnosis, the proper management of the entrance skin dose (ESD) is important. Recently, a small-type optically stimulated luminescence dosimeter (nanoDot OSL dosimeter) was made commercially available by Landauer, and it is hoped that it will be used for ESD measurements in clinical settings. Our objectives in the present study were to propose a method for calibrating the ESD measured with the nanoDot OSL dosimeter and to evaluate its accuracy. The reference ESD is assumed to be based on an air kerma with consideration of a well-known back scatter factor. We examined the characteristics of the nanoDot OSL dosimeter using two experimental conditions: a free air irradiation to derive the air kerma, and a phantom experiment to determine the ESD. For evaluation of the ability to measure the ESD, a calibration curve for the nanoDot OSL dosimeter was determined in which the air kerma and/or the ESD measured with an ionization chamber were used as references. As a result, we found that the calibration curve for the air kerma was determined with an accuracy of 5 %. Furthermore, the calibration curve was applied to the ESD estimation. The accuracy of the ESD obtained was estimated to be 15 %. The origin of these uncertainties was examined based on published papers and Monte-Carlo simulation. Most of the uncertainties were caused by the systematic uncertainty of the reading system and the differences in efficiency corresponding to different X-ray energies.
(出版サイトへのリンク): ● Publication site (DOI): 10.1007/s12194-015-0318-1
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-84937517864

(DOI: 10.1007/s12194-015-0318-1, Elsevier: Scopus) Hiroaki Hayashi, K Takegami, H Okino, K Nakagawa and Yuki Kanazawa :
Development of new educational apparatus to visualize scattered X-rays.,
European Congress of Radiology 2015 (EPOS), C-0073, 2015.

(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2015/C-0073
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2015/C-0073

(DOI: 10.1594/ecr2015/C-0073) Yuki Kanazawa, T Miyati, Hiroaki Hayashi, A Yagi and O Sato :
Optimization of imaging parameter in contrast-enhanced three-dimensional T₁ weighted MRI with fat saturation for head disease.,
European Congress of Radiology 2015 (EPOS), C-1450, 2015.

(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2015/C-1450
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2015/C-1450

(DOI: 10.1594/ecr2015/C-1450) Yuki Kanazawa, Toshiaki Miyati and Osamu Sato :
Hemodynamic analysis of bladder tumors using T₁-dynamic contrast-enhanced fast spin-echo MRI,
European Journal of Radiology, Vol.81, No.8, 1682-1687, 2012.

(要約): Objectives: To evaluate the hemodynamics of bladder tumors, we developed a method to calculate change in R 1 value (ΔR 1) from T 1-dynamic contrast-enhanced fast spin-echo magnetic resonance imaging (T 1DCE-FSE-MRI). Materials and methods: On a 1.5-T MR system, T 1DCE-FSE-MRI was performed. This study was applied to 12 patients with urinary bladder tumor, i.e. urothelial carcinoma. We compared ΔR 1-time and ΔSI-time between a peak in the ΔR 1-time and ΔSI-time curve occurred during the first pass within 60 s. Next, we assessed the slope of increase for 180 s after CA injection (Slope 0-180). Results: The mean slope of the first pass was significantly higher for bladder tumors on both the ΔR 1-time and the ΔSI-time curve compared with normal bladder walls. Moreover, a significant difference was apparent between bladder tumors and normal bladder walls on the mean Slope 0-180 in the ΔR 1-time curve. However, no significant difference in the mean Slope 0-180 was observed on the ΔSI-time curve between bladder tumors and normal bladder walls. Conclusion: T 1DCE-FSE-MRI offers three advantages: quantitative analysis; high-quality (i.e., artifact-free) images; and high temporal resolution even for SE images. Use of ΔR 1 analysis with T 1DCE-FSE-MRI allows more detailed information on the hemodynamics of bladder tumors to be obtained and assists in differentiation between bladder tumors and the normal bladder wall. © 2011 Elsevier Ireland Ltd. All rights reserved.
(キーワード): Aged / Aged, 80 and over / Contrast Media / Echo-Planar Imaging / Female / Gadolinium DTPA / Humans / Image Enhancement / Male / Middle Aged / Neovascularization, Pathologic / Reproducibility of Results / Sensitivity and Specificity / Urinary Bladder Neoplasms
(出版サイトへのリンク): ● Publication site (DOI): 10.1016/j.ejrad.2011.04.013
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 21543177; ● CiNii @ 国立情報学研究所 (CRID): 1050845760881060224; ● Summary page in Scopus @ Elsevier: 2-s2.0-84864434059

(DOI: 10.1016/j.ejrad.2011.04.013, PubMed: 21543177, CiNii: 1050845760881060224, Elsevier: Scopus) Yuki Kanazawa, T Miyati, O Sato and J Tazoe :
Why do we have to calculate T₁ when evaluation of carotid plaque?,
European Congress of Radiology 2011 (EPOS), No.C-1146, 2011.

(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2011/C-1146
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2011/C-1146

(DOI: 10.1594/ecr2011/C-1146) 金澤裕樹, 宮地利明, 八木絢子, 吉田彩, 佐藤修 :
高速スピンエコー法を用いた T₁・T₂同時計測MRI,
医用画像情報学会雑誌, Vol.27, No.4, 111-115, 2010年.

(出版サイトへのリンク): ● Publication site (DOI): 10.11318/mii.27.111
(文献検索サイトへのリンク): ● CiNii @ 国立情報学研究所 (CRID): 1390282679630542848; ● Search Scopus @ Elsevier (DOI): 10.11318/mii.27.111

(DOI: 10.11318/mii.27.111, CiNii: 1390282679630542848) 金澤裕樹, 宮地利明, 井上雄介, 佐藤修 :
高速スピンエコー法を用いた造影ダイナミックT₁値計測MRIの最適条件の検討,
日本放射線技術学会雑誌, Vol.63, No.10, 1127-1132, 2007年.

(要約): For the purpose of continual measurement of the T1 value using the FSE (fast spin-echo) sequence and evaluation of the hemodynamics, we assessed T1 values when the imaging parameters were changed. Moreover, with the imaging parameters derived from this study, dynamic contrast-enhanced MR imaging (MRI) was examined in prostatic disease. First, the T1 value before contrast agent injection was measured with imaging parameters that had different TR and fixed TE. Next, dynamic contrast-enhanced imaging data were acquired for the imaging parameters using TE and TR in the same way as before contrast agent injection, and the T1 value of the tissue at contrast enhancement was measured. In the phantom studies, the TSE imaging parameters with short TE, long TR, and few ETL were connected with the mixed sequence. In dynamic study of the prostate, the difference between normal prostate and prostate cancer became clearer with the time-relaxation rate curve than the time-signal curve. This method using TSE is able to evaluate in greater detail information on hemodynamics and to perform dynamic study with the spin-echo sequence in extensive tissues.
(キーワード): 磁気共鳴映像法 (magnetic resonance imaging) / MRI (MRI) / fast spin-echo / contrast enhancement / dynamic study / contrast enhancement / T1
(出版サイトへのリンク): ● Publication site (DOI): 10.6009/jjrt.63.1127
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 18187894; ● CiNii @ 国立情報学研究所 (CRID): 1390001206361392896; ● Summary page in Scopus @ Elsevier: 2-s2.0-39749179702

(DOI: 10.6009/jjrt.63.1127, PubMed: 18187894, CiNii: 1390001206361392896, Elsevier: Scopus) 金澤裕樹, 井上雄介, 石田憲一 :
Driven Equilibrium Pulseを利用したTurbo Spin Echo法(DRIVE)の基礎的検討,
日本放射線技術学会雑誌, Vol.62, No.7, 1013-1017, 2006年.

(要約): When MR images are obtained with the turbo spin echo (TSE) sequence, DRIVE can be used as a sequence in which the driven equilibrium pulse (DE pulse), a reset pulse, is applied at the TSE echo train to accelerate relaxation time and return to the equilibrium of Mz magnetization. In this study, we examined the extent to which TR could be shortened in DRIVE and how the other parameters of the turbo spin echo sequence influence it. Results: 1) DRIVE is effective when the T2 value is long. 2) It is necessary to set TR at 1000ms or more to obtain image contrast with free water and fat in T2-weighted images for which a conventional turbo spin echo sequence using DRIVE is employed in clinical examination. 3) It is not necessary to consider the influence of the TSE factor when using DRIVE.
(キーワード): 磁気共鳴映像法 (magnetic resonance imaging) / turbo spin echo / driven equilibrium
(出版サイトへのリンク): ● Publication site (DOI): 10.6009/jjrt.62.1013
(文献検索サイトへのリンク): ● CiNii @ 国立情報学研究所 (CRID): 1390282681340494976; ● Summary page in Scopus @ Elsevier: 2-s2.0-33750100940

(DOI: 10.6009/jjrt.62.1013, CiNii: 1390282681340494976, Elsevier: Scopus)

MISC

Yuki Matsumoto, Koji Fujita, Masafumi Harada, Yuki Kanazawa and Miyoshi Mitsuharu :
Characterization of Movement Disorders Using Multimodal Neuroimaging,
European Congress of Radiology (EPOS), 2022.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2022/C-16595
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2022/C-16595

(DOI: 10.26044/ecr2022/C-16595) Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa and Miyoshi Mitsuharu :
Endogenous/exogenous tracers in CEST for pH measurement at 3T MRI,
European Congress of Radiology (EPOS), 2022.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2022/C-16566
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2022/C-16566

(DOI: 10.26044/ecr2022/C-16566) Yuki Matsumoto, Yuki Kanazawa, Yuki Kinjo, Masafumi Harada, Toshiaki Miyati, Hiroaki Hayashi, Mitsuharu Miyoshi, Naoki Maeda, Yasuhisa Kanematsu, Yasushi Takagi and Akihiro Haga :
Evaluation of Blood Flow and Plaque Vulnerability in Carotid Artery Stenosis Focusing on Morphological and Component Characteristics,
Proceedings of the 2022 ISMRM & SMRT ANNUAL MEETING & EXHIBITION, No.3783, 2022, 2022. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Fukuda Nagomi, Kitano Syun, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Brain Tumor Characterization and Assessment using Automatic Detection of Extracellular pH Change,
Proceedings of the 2021 ISMRM & SMRT ANNUAL MEETING & EXHIBITION, No.3749, 2021. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Maki Ohtomo, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Calculation of Concentration of Contrast Media, Relaxivity, Extracellular pH and Oxygen Extraction Fraction for Brain Tumor Characterization,
Proceedings of the 28th Annual Meeting of ISMRM, No.4983, 2020. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Maki Ohtomo, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Calculation of molar relaxivity and concentration map of Gd-DTPA map using quantitative parameter map before and after injection for brain metastasis,
Proceedings of the 27th Annual Meeting of ISMRM, No.4983, 2019. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Maki Ohtomo and Miyoshi Mitsuharu :
Chemical exchange saturation transfer imaging depending on several neurodegenerative diseases at 3T,
Proceedings of the 27th Annual Meeting of ISMRM, No.2795, 2019. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo, Amgalan Enkh Dolgorsuren, Ariumbold Gankhuyag, Takamatsu Shin and Yamashita Yuichi :
Which number of b-value is better for accurate calculation of virtual MR elastography?,
European Congress of Radiology (EPOS), C-1761, 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2019/C-1761
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2019/C-1761

(DOI: 10.26044/ecr2019/C-1761) Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo, Ariunbold Gankhuyag, Amgalan Enkh Dolgorsuren, Takamatsu Shin and Yamashita Yuichi :
Why are shear stiffness and estimated intravoxel incoherent motion map correlated in the liver?,
European Congress of Radiology (EPOS), C-1789, 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2019/C-1789
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2019/C-1789

(DOI: 10.26044/ecr2019/C-1789) Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo and Mitsuharu Miyoshi :
Chemical exchange saturation transfer imaging for neurodegenerative diseases,
Proceedings of the 26th Annual Meeting of ISMRM, No.2096, 2018.

総説・解説

金澤裕樹 :
ISMRM2022in London( ハイブリッド開催)に参加して,
映像情報メディカル増刊号ROUTINE CLINICAL MRI 2023 BOOK 54, Vol.54, No.14, 2022年12月. Yuki Kanazawa and Masafumi Harada :
Editorial for "Chemical Exchange Saturation Transfer (CEST) MRI for Differentiating Radiation Necrosis from Tumor Progression in Brain Metastasis: Application in a Clinical Setting",
Journal of Magnetic Resonance Imaging : JMRI, Vol.Epub ahead of print, Oct. 2022.

(出版サイトへのリンク): ● Publication site (DOI): 10.1002/jmri.28461
(文献検索サイトへのリンク): ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 36269612; ● Search Scopus @ Elsevier (PMID): 36269612; ● Search Scopus @ Elsevier (DOI): 10.1002/jmri.28461

(DOI: 10.1002/jmri.28461, PubMed: 36269612) 金澤裕樹 :
ISMRM 2021 Online に参加して,
映像情報メディカル増刊号 ROUTIN CLINICAL MRI 2022 BOOK53, Vol.53, No.14, 42-47, 2021年12月.

(文献検索サイトへのリンク): ● CiNii @ 国立情報学研究所 (CRID): 1523669556033830272

(CiNii: 1523669556033830272)

講演・発表

Mayuka Seguchi, Yuki Kanazawa, Tosiaki Miyati, Masafumi Harada, Mitsuharu Miyoshi, Hiroaki Hayashi and Akihiro Haga :
How Can We Measure Biological Viscosity Non-Invasively Using MRI?,
RSNA2024 (the 110th Scientific Assembly and Annual Meeting of the Radiological Society of North America), Chicago, Dec. 2024. Ohshiro Ryuji, Yuki Kanazawa, Akihiro Haga and Masafumi Harada :
How Do We Determine the Water Volume in the Central Nervous System?,
RSNA2024 (the 110th Scientific Assembly and AnnualMeeting of the Radiological Society of North America), Chicago, Dec. 2024. Yuki Kanazawa, Yo Taniguchi, Masafumi Harada, Kosuke Ito and Yoshitaka Bito :
Visualization of Human Brain Cortical Layers Using Quantitative Parameter Mapping on a 3 Tesla Scanner,
The 33st Annual Meeting of ISMRM, Singapore, May 2024. Ohshiro Ryuji, Yuki Kanazawa, Akihiro Haga and Masafumi Harada :
Development of numerical phantom converting from electron microscopic analysis to multi-component water fraction for MRI simulator.,
The 33st Annual Meeting of ISMRM, Singapore, May 2024. Sota Goto, Hiroaki Hayashi, Tatsuya Maeda, Kazuki Takegami, Rina Nishigami, Daiki Kobayashi, Takashi Asahara and Yuki Kanazawa :
A novel analysis method to determine surface radiation dose taking into account the incident angle of X-rays during a helical scanning CT examination,
The 3rd International Conference on Radiological Physics and Technology (ICRPT), Yokohama, Apr. 2024. Daiki Kobayashi, Hiroaki Hayashi, Rina Nishigami, Tatsuya Maeda, Takashi Asahara, Yuki Kanazawa, Akitoshi Katsumata, Natsuki Kimoto and Shuichiro Yamamoto :
A correction method for image blurring to derive accurate quantitative material information using an energy resolving photon counting detector,
The 3rd International Conference on Radiological Physics and Technology (ICRPT), Yokohama, Apr. 2024. Rina Nishigami, Hiroaki Hayashi, daiki Kobayashi, Tatsuya Maeda, takashi Asahara, Yuki Kanazawa, Tomonobu Haba, Natsuki Kimoto and Shuichiro Yamamoto :
Suitability of High Tube Voltage Imaging for General Radiography When Using Energy Resolving Photon Counting Detectors,
The 3rd International Conference on Radiological Physics and Technology (ICRPT), Yokohama, Apr. 2024. Hiroaki Hayashi, Tatsuya Maeada, Sota Goto, Kazuki Takegami, Takashi Asahara, Rina Nishigami, Daiki KObayashi, Yuki Kanazawa and Kazuta Yamashita :
Direct dose measurement method during chest CT examination by taking into consideration the X-ray incident direction,
European Congress of Radiology, ECR 2024, Wien, Mar. 2024. Shunsuke Uotani, Yuki Kanazawa, Taniguchi Yo, Ito Kosuke, Bito Yoshitaka, Yuki Matsumoto, Masafumi Harada and Akihiro Haga :
Determining Imaging Parameters of a Gradient-echo Technique for Myelin Water Fraction.,
European Congress of RadiologyECR2024, Wien, Mar. 2024. Rina Nishigami, Hiroaki Hayashi, Daiki Kobayashi, Tatsuya Maeada, Takashi Asahara, Yuki Kanazawa, Natsumi Kimoto and Shuichiro Yamamoto :
Applicability of high tube voltage imaging to achieve accurate quantitative images when applying photon counting detectors to general radiography,
SPIE Medical Imaging 2024, Vol.12925, 129252M, Feb. 2024.

(出版サイトへのリンク): ● Publication site (DOI): 10.1117/12.3004150
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-85193523383

(DOI: 10.1117/12.3004150, Elsevier: Scopus) Yuki Matsumoto, Shotaro Haji, Masafumi Harada, Wataru Sako, Yuki Kanazawa, Yuishin Izumi, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Quantitative Parameter Mapping of Brain Structure and Components in Parkinsons Disease and Progressive Supranuclear Palsy,
RSNA2023 (Radiological Society of North America), Chicago, Nov. 2023. Cheonghae Lee, Hiroaki Hayashi, Daiki Kobayashi, Rina Nishigami, Tatsuya Maeda, Takashi Asahara, Yuki Kanazawa, Akitoshi Katsumata, Natsuki Kimoto and Shuichiro Yamamoto :
Automatic determination algorithm of intrinsic parameters on response function of energy-resolving photon counting imaging detector,
The 2023 IEEE Nuclear Science Symposium and Medical Imaging Conference, Vancouver, Nov. 2023. Daiki Kobayashi, Hiroaki Hayashi, Rina Nishigami, Cheonghae Lee, Tastuya Maeda, Yuki Kanazawa, Akitoshi Katsumata, Natsuki Kimoto and Shuichiro Yamashita :
Blurring correction for calculating functional images using an energy resolving photon counting detector,
The 2023 IEEE Nuclear Science Symposium and Medical Imaging Conference, Vancouver, Nov. 2023. Hiroaki Hayashi, Tatsuya Maeda, Kazuki takegami, Sota Goto, Rina NIshigami, Daiki KObayashi, Takashi Asahara, Yuki Kanazawa, Kazuta Yamashita and Kosaku Higashino :
How can we establish direct radiation dose measurement during CT examinations?,
The 109th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA2023), Chicago, Nov. 2023. Daiki Kobayashi, Hiroaki Hayashi, Rina Nishigami, Cheonghae Lee, Tatsuya Maeada, Takashi Asahara, Yuki Kanazawa, Akitoshi Katsumata, Natsuki Kimoto and Shuichiro Yamamloto :
Will general radiography become more valuable when exploiting the performance of a photon counting detector?,
The 109th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA2023), Chicago, Nov. 2023. Yuki Kanazawa, Tosiaki Miyati, Masafumi Harada, Mitsuharu Miyoshi, Mayuka Seguchi, Hiroaki Hayashi, Yuki Matsumoto, Yasuhisa Kanematsu and Yasushi Takagi :
Metabolic Analysis Within an Atherosclerotic Plaque Using Chemical Exchange Saturation Transfer Imaging,
The 109th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA2023), Chicago, Nov. 2023. Hiroaki Hayashi, tatsuya Maeda, Kazuki Takegami, Rina Nishigami, Daiki Kobayashi, Cheonhae Lee, Takashi Asahara, sota Goto, Miku Ando, Yuki Kanazawa, Kazuta Yamashita, Kosaku Higashino, Shuichi Murakami, Takeshi Konishi and Motochika Maki :
Evidence of exposure dose reduction outside the scanning region during fast scan chest CT examination through the use of an X-ray shield,
20th International Conference on Solid State Dosimetry (SSD20), Viareggio, Sep. 2023. Takashi Asahara, Hiroaki Hayashi, Tatsuya Maeada, Daiki Kobayashi, Sota Goto, Rina Nishigami, Miku Ando, Cheonghae Lee, Yuki Kanazawa, Kazuta Yamashita, Naoki Maeda, Satoshi Imajo and Mitsugi Honda :
An active-type personal dosimeter having functions to derive both incident direction and absolute dose of scattered X-rays during clinical X-ray examinations,
20th International Conference on Solid State Dosimetry (SSD20), Viareggio, Sep. 2023. Yuki Kanazawa, KITANO Shun, Masafumi Harada, Yo Taniguchi, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Myelin Water Atlas Template Derived from Quantitative Parameter Mapping,
The 32st Annual Meeting of ISMRM, Toronto, Jun. 2023. Yuki Kanazawa, Tosiaki Miyati, Masafumi Harada, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Yasuhisa Kanematsu and Yasushi Takagi :
Evaluation of Biological Metabolic Activity within an Atherosclerotic Plaque using Chemical Exchange Saturation Transfer Imaging,
The 32st Annual Meeting of ISMRM, Toronto, Jun. 2023. Mayuka Seguchi, Yuki Kanazawa, Tosiaki Miyati, Masafumi Harada, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Yasuhisa Kanematsu and Yasushi Takagi :
Diffusion weighted-viscosity imaging for atherosclerotic plaques,
The 32st Annual Meeting of ISMRM, Toronto, Jun. 2023. Takashi Asahara, Hiroaki Hayashi, Tatsuya Maeda, Daiki Kobayashi, Sota Goto, Cheonghae Lee, Yuki Kanazawa, Naoki Maeada, Satoshi Imjo and Mitsugu Honda :
A novel function for wearable dosimeters: to determine both incident direction and absolute dose of X-rays during IVR procedure,
The 2nd International Conference on Radiological Physics and Technology (ICRPT), Yokohama, Apr. 2023. Daiki KObayashi, Hiroaki Hayashi, Cheongae Lee, Rina NIshigami, Tatsuya Maeda, Takashi Asahara, Yuki Kanazawa, Akitoshi Katsumata, Natsumi Kimoto and Shuichiro Yamamoto :
A correction method for object edge blurring that is effective for quantitative analysis using photon counting imaging,
The 2nd International Conference on Radiological Physics and Technology (ICRPT), Yokohama, Apr. 2023. Rina Nishigami, Hiroaki Hayashi, Cheonghae Lee, Daiki KObayashi, Tatsuya Maeda, Takashi Asahara, Yuki Kanazawa, tomonobu Haba, Natsuki Kimoto and Shuichiro Yamamoto :
Suitability of High-Tube-Voltage Imaging When Using Energy Resolving Photon Counting Detector (ERPCD): Simulation Study,
The 2nd International Conference on Radiological Physics and Technology (ICRPT), Yokohama, Apr. 2023. Takashi Asahara, Hiroaki Hayashi, Tatsuya Maeda, Sota Goto, Daiki Kobayashi, Cheonghae Lee, Yuki Kanazawa, Naoki Maeda and Mitsugu Honda :
A wearable active-type dosimeter having novel functions to derive both incident direction and absolute dose of scattered X-rays during IVR procedures,
European Congress of Radiology (ECR), Mar. 2023. Nagomi Fukuda, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga :
Development of a B1 correction method without additional scanning VFA T1 map.,
European Congress of Radiology, Wien, Jul. 2022. Yuki Matsumoto, Yuki Kanazawa, Yuki Kinjo, Masafumi Harada, Toshiaki Miyati, Hiroaki Hayashi, Mitsuharu Miyoshi, Naoki Maeda, Yasuhisa Kanematsu, Yasushi Takagi and Akihiro Haga :
Evaluation of Blood Flow and Plaque Vulnerability in Carotid Artery Stenosis Focusing on Morphological and Component Characteristics,
ISMRM 30th Annual Meeting, London, May 2022. Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi and Yuki Matsumoto :
Evaluation of brain tumor and surrounding tissue activity using multi-pool CEST imaging on 3 Tesla scanner,
Joint Annual Meeting ISMRM-ESMRMB & ISMRT 31st Annual Meeting, London, May 2022. Nagomi Fukuda, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga :
Development of self-calibrating B1 correction for three-dimensional variable flip angle T1 mapping,
Joint Annual Meeting ISMRM-ESMRMB & ISMRT 31st Annual Meeting, London, May 2022. Shun Kitano, Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Conversion map from quantitative parameter mapping to myelin water fraction,
Joint Annual Meeting ISMRM-ESMRMB & ISMRT 31st Annual Meeting, London, May 2022. Natsuki Ikemitsu, Yuki Kanazawa, Akihiro Haga, Hiroaki Hayashi, Yuki Matsumoto and Masafumi Harada :
Determination of Alzheimer's disease based on morphology and atrophy using machine learning combined with automated segmentation.,
Joint Annual Meeting ISMRM-ESMRMB & ISMRT 31st Annual Meeting, London, May 2022. Cheonghae Lee, Hiroaki Hayashi, Natsumi Kimoto, Tatsuya Maeda, Yuki Kanazawa, Akitoshi Katsumata and Shuichiro Yamamoto :
Bone and soft-tissue image generation method based on one shot X-ray exposure using a photon-counting detector,
Joint International Conference on Radiological Physics and Technology, Yokohama, Apr. 2022. Fukuda Nagomi, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga :
Variable flip angle T1 mapping without acquiring data for B1 correction,
Joint International Conference on Radiological Physics and Technology, Yokohama, Apr. 2022. Natsuki Ikemitsu, Yuki Kanazawa, Masafumi Harada, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yo Taniguchi, Yoshitaka Bito and Akihiro Haga :
Determination of white matter structure index for voxel basedmorphometry and connectivity analysis.,
European Congress of Radiology, Wien, Mar. 2022. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa and Miyoshi Mitsuharu :
Endogenous/exogenous tracers in CEST for pH measurement at 3T MRI,
European Congress of Radiology, Wien, Mar. 2022. Yuki Matsumoto, Koji Fujita, Masafumi Harada, Yuki Kanazawa and Miyoshi Mitsuharu :
Characterization of Movement Disorders Using Multimodal Neuroimaging,
European Congress of Radiology, Wien, Mar. 2022. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Yo Taniguchi, Masaharu Ono and Yoshitaka Bito :
What Is The Extracellular pH Of Brain Tumors And How Can We Detect Brain Tumors Using Gadolinium-based-contrast Agents?,
RSNA2021 (Radiological Society of North America), Chicago, Nov. 2021. Naoki Maeda, Yuki Kanazawa, Yuki Kinjo, Yuki Matsumoto, Masafumi Harada, Tosiaki Miyati, Hiroaki Hayashi, Mitsuharu Miyoshi, Yasuhisa Kanematsu, Yasushi Takagi and Akihiro Haga :
Is it possible to evaluate morphological carotid artery stenosis information using NASCET criteria?,
RSNA2021 (Radiological Society of North America), Chicago, Nov. 2021. Cheonghae Lee, Hiroaki Hayashi, Natsumi Kimoto, Tatsuya Maeda, Miku Ando, Yuki Kanazawa, Akitoshi Katsumata, Shuichiro Yamamoto and Masahiro Okada :
Bone and soft-tissue images extraction through derivation of effective atomic number image using photon-counting detector,
IEEE(MIC), Online, Nov. 2021.

(出版サイトへのリンク): ● Publication site (DOI): 10.1109/NSS/MIC44867.2021.9875683
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-85139133825

(DOI: 10.1109/NSS/MIC44867.2021.9875683, Elsevier: Scopus) Cheonghae Lee, Hiroaki Hayashi, Natsumi Kimoto, Tatsuya Maeda, Miku Ando, Yuki Kanazawa, Akitoshi Katsumata, Shuichiro Yamamoto and Masahiro Okada :
Bone and soft-tissue images extraction through derivation of effective atomic number image using photon-counting detector.,
IEEE(MIC), On-line meeting, Oct. 2021. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Yo Taniguchi, Masaharu Ono and Yoshitaka Bito :
Brain Tumor Characterization and Assessment using Automatic Detection of Extracellular pH Change,
ISMRM 29th Annual Meeting, Online meeting, May 2021. Naoki Maeda, Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Derivation of Water Exchange Constants between Components using Quantitative Parameter Mapping (QPM),
ISMRM 29th Annual Meeting, Online, May 2021. Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Syun Kitano, Nagomi Fukuda, Yuki Matsumoto, Hiroaki Hayashi, Kosuke Ito, Yoshitaka Bito and Akihiro Haga :
Myelin imaging derived quantitative parameter mapping compared to myelin water fraction,
ISMRM 29th Annual Meeting, Online, May 2021. Takashi Asahara, Hiroaki Hayashi, Natsumi Kimoto, Sota Goto, Kazuki Takegami, Tatsuya Maeda, Chenghae Lee, Yuki Kanazawa, Kazuta Yamashita and Higashino Kosaku :
How can we perform actual dose measurement? Clinically applicable procedures and its impact,
RSNA2020, Online, Dec. 2020. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Maki Ohtomo, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Calculation of Concentration of Contrast Media, Relaxivity, Extracellular pH and Oxygen Extraction Fraction for Brain Tumor Characterization,
ISMRM 28th Annual Meeting, Paris, Aug. 2020. Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi, Takashi Abe, Yuki Matsumoto and Yasushi Takagi :
Characterization of Brain Tumors using Amide Proton and Nuclear Overhauser Effect at 3 Tesla MR Scanner,
ISMRM Virtual Conference, Aug. 2020. Yuki Kanazawa, Masafumi Harada, Tosiaki Miyati, Takashi Abe, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Yasuhisa Kanematsu and Yasushi Takagi :
Chemical Exchange Saturation Transfer Imaging for Atherosclerotic Plaques,
ISMRM Virtual Conference, Aug. 2020. Hasegawa Yu, Akihiro Haga, Sakata Dousatsu, Yuki Kanazawa, Masahide Tominaga, Motoharu Sasaki, Imae T. and Nakagawa Keiichi :
Estimation of X-ray energy spectrum for CT scannerfrom percentage depth dose measurement,
2020 JOINT AAPM COMP meeting, Jul. 2020. Kazuki Takegami, Hiroaki Hayashi, Takashi Asahara, Sota Goto, Emi Tomita, Natsumi Kimoto, Yuki Kanazawa and Shohei Kudomi :
Dose calibration factor of an OSL dosimeter during CT examination to measure exposure dose of patients taking into consideration proper X-ray quality,
European Congress of Radiology, No.C-01393, Online, Jul. 2020.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2020/C-01393
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2020/C-01393

(DOI: 10.26044/ecr2020/C-01393) Maeda Naoki, Yuki Kanazawa, Masafumi Harada, Tanigichi Yo, Yuki Matsumoto, Takashi Abe, Hiroaki Hayashi, Ono Masaharu and Bito Yoshitaka :
Multicomponent T1 Relaxometry Analysis using Quantitative Parameter Mapping Magnetic Resonance Imaging,
European Congress of Radiology, Wien, Mar. 2020.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2020/C-08767
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2020/C-08767

(DOI: 10.26044/ecr2020/C-08767) Wada Yugo, Yuki Kanazawa, Masafumi Harada, Naoki Maeda, Yuki Matsumoto, Takashi Abe, Hiroaki Hayashi, Miyoshi Mitsuharu and Carl Michel :
Multi-components analysis of brain using ultrashort echo time magnetic resonance imaging,
European Congress of Radiology, Wien, Mar. 2020.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2020/C-08766
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2020/C-08766

(DOI: 10.26044/ecr2020/C-08766) Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
How does synthetic MRI depict biological information? A step toward planning for deep brain stimulation (DBS),
European Congress of Radiology, Wien, Mar. 2020. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Maki Ohtomo, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Simultaneously Calculation of Concentration of Contrast Media, Relaxivity, and Oxygen Extraction Fraction using Quantitative Parameter Mapping,
RSNA2019 (Radiological Society of North America), Chicago, Dec. 2019. Kimoto Natsumi, Hiroaki Hayashi, Asakawa Takumi, Asahara Takashi, Maeda Tatsuya, Katsumata Akitoshi, Yuki Kanazawa, Koyama Shuji, Yamamoto Shuichiro and Okada Masahiro :
Photon counting technique: How to analyze a novel quantitative image?,
RSNA2019 (Radiological Society of North America), Chicago, Dec. 2019. Kimoto Natsumi, Hayashi Hiroaki, Asakawa Takumi, Asahara Takashi, Maeda Tatsuya, Yuki Kanazawa, Katsumata Akitoshi, Yamamoto Shuichiro and Okada Masahiro :
Feasibility study of photon counting detector for producing effective atomic number image,
IEEE Nuclear Science Symposium and Medical Imaging Conference, Manchester, Nov. 2019. GOTO Sota, HAYASHI Hiroaki, TOMITA Emi, ASAHARA Takashi, KIMOTO Natsumi, Yuki Kanazawa, YAMAGUCHI Hidetoshi and SHIMIZU Morihito :
Novel Disk-Shaped OSL Dosimeter Having Smaller Angular Dependence,
19th International Conference on Solid State Dosimetry (SSD19), Hiroshima, Sep. 2019. Tomita Emi, Hayashi Hiroaki, Asahara Takashi, Kimoto Natsumi, Goto Sota, Yuki Kanazawa, Shitakubo Yasufumi, Sakuragawa Kanako, Hitoshi Ikushima, Okazaki Tohru and Hashizume Takuya :
Development of a Clinically Applicable Rectum Dosimeter for Brachytherapy using an Optically Stimulated Luminescence Dosimeter,
19th International Conference on Solid State Dosimetry (SSD19), Hiroshima, Sep. 2019. Takegami Kazuki, Hayashi Hiroaki, Kimoto Natsumi, Goto Sota, Tomita Emi, Takashi Asahara, Mihara Yoshiki and Yuki Kanazawa :
Practical calibration curve for a small-type OSL dosimeter to measure exposure dose of patients during medical X-ray diagnosis,
19th International Conference on Solid State Dosimetry (SSD19), Hiroshima, Sep. 2019. Asahara Takashi, Hayashi Hiroaki, Goto Sota, Tomita Emi, Kimoto Natsumi, Asakawa Takumi, Takegami Kazuki, Yuki Kanazawa, Okazaki Tohru and Hashizume Takuya :
Precise dose calibration method of OSL dosimeter with help of X-ray spectra toward exposure dose evaluation of eye lens,
19th International Conference on Solid State Dosimetry (SSD19), Hiroshima, Sep. 2019. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Maki Ohtomo, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Calculation of molar relaxivity and concentration map of Gd-DTPA map using quantitative parameter map before and after injection for brain metastasis,
ISMRM 27th Annual Meeting, Montreal, May 2019. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Maki Ohtomo and Miyoshi Mitsuharu :
Chemical exchange saturation transfer imaging depending on several neurodegenerative diseases at 3T,
ISMRM 27th Annual Meeting, Montreal, May 2019. Yuki Kanazawa, Chiba Daiki, Masafumi Harada, Miyati Tosiaki, Miyoshi Mitsuharu, Hiroaki Hayashi, Yuki Matsumoto, Takashi Abe and Akihiro Haga :
Thermal sensitive pH imaging using CEST,
ISMRM 27th Annual Meeting, Montreal, May 2019. Yuki Kanazawa, Masafumi Harada, Taniguchi Yo, Hiroaki Hayashi, Takashi Abe, Maki Ohtomo, Yuki Matsumoto, Ono Masafumi, Bito Yoshitaka and Akihiro Haga :
Myelin imaging derived from quantitative parameter mapping,
ISMRM 27th Annual Meeting, Montreal, May 2019. Takashi Abe, Yuki Matsumoto, Yuki Kanazawa, Yoichi Otomi, Maki Otomo, Moriaki Yamanaka, Mihoko Kondou, Saya Matsuzaki, Ariundbold Gankhuyag, Enkhamgalan Dolgorsuren, Oyundari Gonchigsuren and Masafumi Harada :
Comparing neural networks for synthesizing FLAIR images from T1WI and T2WI,
ISMRM 27th Annual Meeting, Montreal, Apr. 2019. Natsumi Kimoto, Hiroaki Hayashi, Takumi Asakawa, Takashi Asahara, Akitoshi Katsumata, Yuki Kanazawa, Shuichiro Yamamoto and Masahiro Okada :
Effective atomic number image produced with energy-resolved photon counting detector toward the development of next-generation plain X-ray diagnosis,
European Congress of Radiology, Wien, Mar. 2019. Emi Tomita, Hiroaki Hayashi, Takashi Asahara, Yasufumi Shitakubo, Kanako Sakuragawa, Hitoshi Ikushima, Yuki Kanazawa, Tohru Okazaki and Takuya Hashizume :
Evaluation of dose to risk organ during brachytherapy for cervical cancer using a novel passive rectum dosimeter,
European Congress of Radiology, Wien, Mar. 2019. Takashi Asahara, Hiroaki Hayashi, Emi Tomita, Yoshiki Mihara, Sota Goto, Yuki Kanazawa, Natsumi Kimoto, Takumi Asakawa and Tohru Okazaki :
Actual dose measurements of assistant during pediatric X-ray examination with a precisely calibrated optically stimulated luminescence dosimeter,
European Congress of Radiology, Wien, Mar. 2019. Tohru Okazaki, Hiroaki Hayashi, Sota Goto, Takashi Asahara, Emi Tomita, Yuki Kanazawa, Takuya Hashizume, V Cruz and H W Cheng :
Determining the difference of calibration factors in diagnostic X-rays and mono-energetic X-rays of the small type OSL dosimeter for a more precise dose evaluation in diagnostic X-ray examinations,
European Congress of Radiology, Wien, Mar. 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2019/C-0212
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2019/C-0212

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2019/C-1825
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2019/C-1825

(DOI: 10.26044/ecr2019/C-1825) Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo, Ariunbold Gankhuyag, Amgalan Enkh Dolgorsuren, Takamatsu Shin and Yamashita Yuichi :
Why are shear stiffness and estimated intravoxel incoherent motion map correlated in the liver?,
European Congress of Radiology, Wien, Mar. 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2019/C-1789
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2019/C-1789

(DOI: 10.26044/ecr2019/C-1789) Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo, Amgalan Enkh Dolgorsuren, Ariumbold Gankhuyag, Takamatsu Shin and Yamashita Yuichi :
Which number of b-value is better for accurate calculation of virtual MR elastography?,
European Congress of Radiology, Wien, Mar. 2019.

(出版サイトへのリンク): ● Publication site (DOI): 10.26044/ecr2019/C-1761
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.26044/ecr2019/C-1761

(DOI: 10.26044/ecr2019/C-1761) Yuki Kanazawa, Chiba Daiki, Masafumi Harada, Miyati Tosiaki, Miyoshi Mitsuharu, Hayashi Hiroaki and Akihiro Haga :
Quantitative evaluation of local offset frequency for CEST imaging,
The 3rd Annual Scientific Meeting of the Japanese Chapter of ISMRM, Nagoya, Dec. 2018. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo and Miyoshi Mitsuharu :
Chemical exchange saturation transfer imaging for brain tumors,
RSNA2018 (Radiological Society of North America), Chicago, Nov. 2018. GOTO Sota, Hiroaki Hayashi, TOMITA Emi, KIMOTO Natsumi, UEHARA Takumi, Yuki Kanazawa, ASAKAWA Takumi, ASAHARA Takashi, OKAZAKI Tohru and HASHIZUME Takuya :
Trial study for development of a novel-formed dosimeter having lower angular dependence,
18th Asia-Oceania Congress of Medical Physics (AOCMP), Malaysia, Nov. 2018. Natsumi Kimoto, Hiroaki Hayashi, Takashi Asahara, Emi Tomita, Sota Goto, Yuki Kanazawa, Shuichiro Yamamoto, Masahiro Okada and Masaki Yamasaki :
Reproduction of response functions of a multi-pixel-type energy-resolved photon counting detector while taking into consideration interaction of X-rays, charge sharing and energy resolution,
25th International Symposium on Room-Temperature Semiconductor X-ray & Gamma-ray Detectors, Sydney, Nov. 2018. Tomita Emi, Hiroaki Hayashi, Asahara Takashi, Shitakubo Yasufumi, Sakuragawa Kanako, Hitoshi Ikushima, Yuki Kanazawa, Okazaki Tohru and Hashizume Takuya :
First Trial of Actual Dose Measurement of Organ at Risk During Brachytherapy for Cervical Cancer in Tokushima University Hospital,
Second International Seminar and Workshop on Technological Competency as Caring in the Health Science, Tokushima, Aug. 2018. Yuki Kanazawa, Kotaro Baba, Tosiaki Miyati, Masafumi Harada, Hiroaki Hayashi, Ikuho Kosaka, Mitsuharu Miyoshi, Michael Carl and Yuki Matsumoto :
Does the amount of signal change depend on calcium concentration in lipid-rich core plaque?,
ISMRM 26th Annual Meeting, Paris, Jun. 2018. Yuki Kanazawa, Toshiaki Sasaki, Hiroaki Hayashi, Kotaro Baba, Ikuho Kosaka, Yuki Matsumoto, Mitsuharu Miyoshi and Masafumi Harada :
T1 dependency of magnetization transfer effect in human brain,
ISMRM 26th Annual Meeting, Paris, Jun. 2018. Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi, Ikuho Kosaka, Kotaro Baba, Hiroaki Hayashi and Yuki Matsumoto :
Nuclear Overhauser enhancement effect of low B1 power CEST RF in human brain at 3.0 T,
ISMRM 26th Annual Meeting, Paris, Jun. 2018. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo and Mitsuharu Miyoshi :
Chemical exchange saturation transfer imaging for neurodegenerative diseases,
ISMRM 26th Annual Meeting, Paris, Jun. 2018. Cruz Lorenzo Estacio Vergil, Hiroaki Hayashi, Tomita Emi, Yuki Kanazawa, Goto Sota, Mihara Yoshiki, Kimoto Natsumi, Asahara Takashi, Tada Keiji, Kasai Ryosuke, Higashino Kosaku, Yamashita Kazuta, Okazaki Tohru and Hashizume Takuya :
Radiation dose measurement in pediatric CT examination using nanoDot dosimeters, a small type Optically Stimulated Luminescence (OSL) dosimeter,
5th Asian and Oceanic IRPA Regional Congress on Radiation Protection (AOARP5), Melbourne, May 2018. Okazaki Tohru, Hiroaki Hayashi, Asahara Takashi, Goto Sota, Mihara Yoshiki, Tomita Emi, Yuki Kanazawa, Kimoto Natsumi, Hashizume Takuya, Cruz LE Vergil, Hsin Wei Cheng and Yokoyama Sumi :
Proper Calibration Factor of Small Type OSL Dosimeter for Evaluating Eye Lens Dose of Operators during X-ray Fluoroscopic Procedure,
th Asian and Oceanic IRPA Regional Congress on Radiation Protection (AOARP5), Melbourne, May 2018. Tohru Okazaki, Hiroaki Hayashi, Takashi Asahara, Sota Goto, Yoshiki Mihara, Emi Tomita, Yuki Kanazawa, Natsumi Kimoto, Takuya Hashizum, Vergil LE Cruz and Cheng Wei Hsin :
Eye lens dose evaluation of medical staff during the X-ray fluoroscopic procedure using Optically Stimulated Luminescence dosimeter ~ Influence of incident X-ray energy fluctuation on response of the dosimeter ~,
51st Annual Meeting of TWSRT and the 25th East Asia Conference of Radiological Technologists, Taiwan, Mar. 2018. Hsin Wei Cheng, Hiroaki Hayashi, Tomita Emi, Tada Keiji, Mihara Yoshiki, Kimoto Natsumi, Kasai Ryosuke, Yuki Kanazawa, Cruz LE Vergil, Hashizume Takuya and Kobayashi Ikuo :
(CT) (OSL) (nanoDot),
51st Annual meeting of Taiwan Society of Radiation Technology, Taiwan, Mar. 2018. Tadashi Asahara, Hiroaki Hayashi, Emi Tomita, Sota Goto, Natsumi Kimoto, Kenji Yamada, Sumi Yokoyama, Yuki Kanazawa and Toru Okazaki :
Phantom study toward accurate measurement of eye lens dose exposure of operator during transfemoral cardiac catheterization using fluoroscopy examination with an OSL dosimeter,
European Congress of Radiology, Wien, Mar. 2018.

(要約): [Aim and objectives] During transfemoral cardiac catheterization procedure using fluoroscopy, the operator is exposed to scattered X-rays. We focused our attention on the accurate dose measurement of eye lens using a small-type OSL dosimeter. The eye lens is exposed with X-rays scattered by patient and those penetrating protective goggles, therefore, the OSL dosimeter should be calibrated with the appropriate radiation. The aim of this study is to perform accurate calibration of OSL dosimeter for the determination of eye lens dose exposure. [Materials and Methods] A phantom study was performed under clinical conditions in which the catheterization procedure was assumed. Then, using a CdTe detector, energy spectrum of scattered X-ray was measured at the eye lens position. Irradiation conditions were set at 74 kV, 0.9 mA, 15 fps, and 30 minutes. Air kerma and absorbed dose of OSL dosimeter were derived from the measured spectrum, and calibration factor of OSL dosimeter was calculated from their ratio. Using Monte-Carlo simulation, necessary corrections concerning beam hardening in protective goggles and back scattering from head of operator were properly calculated. [Result] Using fluoroscopy, X-ray spectrum was obtained, and the spectrum was corrected for by response function of CdTe detector and the Klein-Nishina formula. The calibration factor for scattered X-rays was determined and this calibration factor was in good agreement with that determined with 80 kV direct X-ray. [Conclusion] We evaluated the difference in calibration factor caused by scattered X-ray. Then, we found that calibration factor for measuring the eye lens dose exposure was similar to the data for 80 kV direct X-ray.
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2018/C-0044
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2018/C-0044

(DOI: 10.1594/ecr2018/C-0044) Kazuki Takegami, Hiroaki Hayashi, Natumi Kimoto, Yoshiki Mihara, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Fumio Hayashi, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Universal calibration curve for a small-type OSL dosimeter to be used for direct dose measurements of direct, scattered and penetrating X-rays in the diagnostic region,
Radiological Society of North America (RSNA), Chicago, Dec. 2017.

(要約): (1)Aims: We hope to find a suitable dosimeter, which can measure incident, scattered and penetrating X-rays. In this study, we propose a new procedure to calibrate the OSL dosimeter. (2)Experiment & results: Initially, we constructed a calibration curve of air-kerma (direct X-rays) with comparison between the OSL dosimeter and an ionization chamber. Second, we evaluated the accuracy of the above calibration curve when the following conditions were applied; 1) entrance-skin dose, and 2) air-kerma of scattered X-rays and 3) penetrating X-rays through a soft-tissue equivalent phantom. We then found that the above calibration curve can be used in all situations if we adopt 15% of uncertainty. Finally, the X-ray spectra related to those conditions were measured, and with the data on basic characteristics of the dosimeter, the result of 15% uncertainty was verified mathematically. (3)Conclusion: With 15% uncertainty, we can use the OSL dosimeter without considerations of energy dependence, angular dependence etc. This study enabled the OSL dosimeter to manage the exposure dose of medical staff, assistants and patients.

Tohru OKAZAKI, Hiroaki Hayashi, Emi TOMITA, Sota GOTO, Keiji TADA, Yoshiki MIHARA, Natsumi KIMOTO, Ryosuke Kasai, Yuki Kanazawa, Vergil LE CRUZ, Takuya HASHIZUME, Cheng Wei Hsin and Ikuo KOBAYASHI :
Practical phantom study using small-type OSL dosimeter toward direct dose measurement during pediatric CT examination,
AOCMP-AMPICON 2017, Jaipur, Nov. 2017. Yuki Matsumoto, Yuki Kanazawa, Toshiaki Sasaki, Natsuki Ikemitsu, Hiroaki Hayashi, Mitsuharu Miyoshi, Masafumi Harada and Hideki Otsuka :
Which is More Important for Quantitative Susceptibility Mapping? SNR of Phase vs Spin Dephasing.,
Radiological Society of North America (RSNA), Chicago, Nov. 2017. Natsuki Ikemitsu, Yuki Kanazawa, Hiroaki Hayashi, Yoshiki Mihara, Emi Tomita, Yuki Matsumoto, Tohru Okazaki, Takuya Hashizume and Masafumi Harada :
Can OSL dosimetry measurement be applied to MR imaging during MR-LINAC treatment?,
RSNA2017 (Radiological Society of North America), Chicago, Nov. 2017. Natsumi Kimoto, Hiroaki Hayashi, Takashi Asahara, Emi Tomita, Sota Goto, Yoshiki Mihara, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki, Masahiro Okada and Daisuke Hashimoto :
Potential of photon counting technique for next-generation type X-ray diagnostic system: To provide new medical image concerning effective atomic numbers using plain X-ray,
RSNA2017 (Radiological Society of North America), Chicago, Nov. 2017. Hiroaki Hayashi, Emi Tomita, Takashi Asahara, Yasufumi Shitakubo, Kanako Sakuragawa, Hiroshi Saegusa, Hitoshi Ikushima, Yuki Kanazawa, Sota Goto, Natsumi Kimoto, Yoshiki Mihara, Yoshinori Miyahara, Tohru Okazaki, Takuya Hashizume and Vergil Estacio Lorenzo Cruz :
Development of a new in-vivo measurement system by means of OSL dosimeters during brachytherapy for cervical cancer,
RSNA2017 (Radiological Society of North America), Chicago, Nov. 2017. Cheng Wei Hsin, Tohru OKAZAKI, Takuya HASHIZUME, Hiroaki Hayashi, Emi TOMITA, Keiji TADA and Yuki Kanazawa :
Evaluating the Influence of the Small-type Optically Stimulated Luminescence (OSL) Dosimeter on CT Images for Radiation Dose Measurement of Patient,
The 3rd International Conference on Radiological Science and Technology, Hiroshima, Oct. 2017. Yoshiki MIHARA, Hiroaki Hayashi, Takashi ASAHARA, Sota GOTO, Natsumi KIMOTO, Yuki Kanazawa and Tohru OKAZAKI :
Precise calibration factor of small-type OSL dosimeter with the aim toward analysis of exposure doses caused by scattering X-ray in the diagnostic region,
The 3rd International Conference on Radiological Science and Technology, Hiroshima, Oct. 2017. Emi TOMITA, Hiroaki Hayashi, Sota GOTO, Keiji TADA, Yuki Kanazawa, Tohru OKAZAKI and Takuya HASHIZUME :
Direct measurement of exposure doses using a small-type OSL dosimeters during pediatric CT examination,
The 3rd International Conference on Radiological Science and Technology, Hiroshima, Oct. 2017. Natsumi Kimoto, Hiroaki Hayashi, Takashi Asahara, Emi Tomita, Sota Goto, Yoshiki Mihara, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki, Masahiro Okada and Daisuke Hashimoto :
Novel material identification method using three energy bins of a photon counting detector taking into consideration Z-dependent beam hardening effect correction with the aim of producing an X-ray image with information of effective atomic number,
2017 IEEE Nuclear Science Symposium & Medical Imaging Conference, Atlanta, Oct. 2017.

(出版サイトへのリンク): ● Publication site (DOI): 10.1109/NSSMIC.2017.8533059
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-85058464345

(DOI: 10.1109/NSSMIC.2017.8533059, Elsevier: Scopus) Hiroaki Hayashi, Emi TOMITA, Sota GOTO, Natsumi KIMOTO, Keiji TADA, Ryosuke Kasai, Yuki Kanazawa, Yoshiki MIHARA, Takashi ASAHARA, Tohru OKAZAKI, Takuya HASHIZUME and Vergil LE CRUZ :
Direct Dose Measurement of Patients during Pediatric Computed Tomography Examination,
International Symposium On Radiation Safety and Detection Technology (ISORD-9), Nagoya, Jul. 2017. Vergil E. Lorenzo Cruz, Tohru OKAZAKI, Hiroaki Hayashi, Yoshiki MIHARA, Takashi ASAHARA, Natsumi KIMOTO, Hiroki OKINO, Yuki Kanazawa, Takuya HASHIZUME and Ikuo KOBAYASHI :
Energy and Angular Dependence of the small type OSL Dosimeter in Diagnostic and Nuclear Medicine Regions using Monte Carlo Simulation,
International Symposium On Radiation Safety and Detection Technology (ISORD-9), Nagoya, Jul. 2017. Emi TOMITA, Hiroaki Hayashi, Takashi ASAHARA, Kanako SAKURAGAWA, Yasufumi SHITAKUBO, Hiroshi SAEGUSA, Hitoshi Ikushima, Yuki Kanazawa, Sota GOTO, Tohru OKAZAKI, Takuya HASHIZUME and Vergil LE CRUZ :
Direct Radiation Dose Measurement of Rectum during High-Dose-Rate 192Ir Brachytherapy for Cervical Cancer Treatment,
International Symposium On Radiation Safety and Detection Technology (ISORD-9), Nagoya, Jul. 2017. Tohru OKAZAKI, Hiroaki Hayashi, Yoshiki MIHARA, Takashi ASAHARA, Natsumi KIMOTO, Yuki Kanazawa, Kousaku Higashino, Kazuta YAMASHITA, Sumi YOKOYAMA, Kazuki TAKEGAMI, Takuya HASHIZUME and Vergil LE CRUZ :
Applicability of Practical Calibration of a Small-type OSL Dosimeter For Measuring the Exposure Doses Effected by Scattered and Penetrating X-rays,
International Symposium On Radiation Safety and Detection Technology (ISORD-9), Nagoya, Jul. 2017. Takashi ASAHARA, Hiroaki Hayashi, Emi TOMITA, Kanako SAKURAGAWA, Hiroshi SAEGUSA, Yasufumi SHITAKUBO, Hitoshi Ikushima, Yuki Kanazawa, Yoshiki MIHARA, Yoshinori MIYAHARA, Tohru OKAZAKI, Takuya HASHIZUME and Vergil CRUZ :
Development of Novel Rectum Dosimeter using OSL sheet with the aim of Direct Dose Measurement of Organ Dose during Brachytherapy,
International Symposium On Radiation Safety and Detection Technology (ISORD-9), Nagoya, Jul. 2017. Mitsuharu Miyoshi, Masafumi Harada, Yuki Kanazawa and Hiroyuki Kabasawa :
CEST and Binding Water MT Separation in Brain Tumor by Multi Pool Model CEST Peak Extraction Method,
ISMRM 25th Annual Meeting, Honolulu, Apr. 2017. Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Toshiaki Sasaki, Natsuki Ikemitsu and Michael Carl :
Dura Mater imaging with UTE T2* Mapping,
ISMRM 25th Annual Meeting, Honolulu, Apr. 2017. Yuki Kanazawa, Masafumi Harada, Mitsuharu Miyoshi, Yuki Matsumoto, Hiroaki Hayashi, Toshiaki Sasaki and Natsuki Ikemitsu :
Baseline of Chemical Exchange Saturation Transfer Imaging for Brain,
ISMRM 25th Annual Meeting, Honolulu, Apr. 2017. Cheng Wei hsin, 林裕晃, Kazuki Takegami, Yoshiki Mihara, Natsumi Kimoto, 金澤裕樹, Okazaki Tohru, Hashizume Takuya, Kobayashi Ikuo :
小型光刺激發光劑量計測量診斷範圍之輻射劑量的可能性評估,
The 50th Annual Meeting of TWSRT and the International Conference of Medical Imaging, Taiwan, 2017年3月. Yoshiki Mihara, Hiroaki Hayashi, Kenji Yamada, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Ryosuke Kasai, Tohru Okazaki and Takuya Hashizume :
Basic study for internal dose evaluation during CT examination by means of small-type OSL dosimeter,
European Congress of Radiology, Vienna, Mar. 2017.

(要約): [Aims and objectives] We plan to manage the patient dose exposure during computed tomography (CT) examination using a small-type OSL dosimeter. The OSL dosimeter can measure entrance skin dose (ESD) directly, but the internal dose can't be measured. The aim of this study is to clarify the relationship between the ESD and internal dose during the CT examination. [Methods and materials] We constructed an abdominal phantom, in which OSL dosimeters can be implanted in, and used this phantom to measure external and internal doses during CT examination. The typical irradiation conditions were as follow, 64 rows of detectors, 120 kV, 600 mA, PF (pitch factor) = 1.484 in helical scan mode. Additionally, we analyzed the contribution of X-rays, which were generated from different angles to the dosimeter; namely, angular dependences of 0-360 degrees at 45 degree intervals were evaluated experimentally. [Results] The ESDs and internal doses showed similar values, however the deviations between them were completely different; maximum deviation of ESD was found to be 30% and that of internal dose was at the most 5%. The deviation in ESDs is explained by the phenomenon in which some dosimeters were irradiated by direct X-ray and others were not. However, the small deviation between internal doses was explained by the phenomenon in which dosimeters were mainly irradiated by scattered X-rays. [Conclusion] In this study, we analyzed the relationship between ESD and internal dose for direct dose measurement of patient dose undergoing CT examination. The ESDs show relatively large fluctuations, on the other hand, the internal doses show small deviations.

Yuki Matsumoto, Yuki Kanazawa, Toshiaki Sasaki, Natsuki Ikemitsu, Hiroaki Hayashi, Mitsuharu Miyoshi, Masafumi Harada and Hideki Otsuka :
Phase Correction for Quantitative Susceptibility Mapping (QSM) using T2* Mapping,
The 5th International Congress on Magnetic Resonance Imaging, Vol.2017, No.FA, 111, Seoul, Mar. 2017.

(要約): Objectives : The purpose of this study is to develop a phase correction method focusing on the SNR of phase and to improve the quantitative measurement of QSM. Methods : On a 3.0 T MRI system (Discovery MR750; GE Healthcare), using three-dimensional spoiled gradient-echo (3D-SPGR) sequence with multiple TEs were used in this study. The imaging parameters were TE, 12 echoes from 3.1 to 51.7 ms (ΔTE = 4.4 ms); repetition time, 55.5 ms; spatial resolution, 1.0 × 1.0 × 1.0 mm; and pixel bandwidth, 244.1 Hz. We conducted a phantom experiment in this study. Five tubes were filled with different concentrations (100, 150, 200, 250, and 300 mg/mL) of calcium hydroxyapatite samples. In this study, we focused on the computation of off-set frequency of each voxel (i.e., field map estimation). At first, we calculate the TE having the maximum for our setting number of echo from the measured T2* map. Second, the ``appropriate TE dataset'' was defined as the maximum SNR dataset with appropriate TE and two datasets with neighboring TE. Third, after estimating the field map using the appropriate TE dataset, a corrected phase angle at each phase angle of the appropriate TE dataset was calculated from a mean resultant length which is the length of the average vectors calculated from all phase angles. Then, the corrected phase angle was defined from mean resultant length. Finally, all phase angles in FOV were corrected for each appropriate TE dataset. Results : The linearity of the relationship between the measured susceptibility and the concentration of hydroxyapatite in the corrected phase dataset was significantly higher than other methods (R = 0.30 VS 0.97). Conclusions : The correction method in QSM using phase correction method makes it possible to more accurately obtain susceptibility information of tissue having a short T2*.
(キーワード): QSM / echo time / T2* / SNR of phase / susceptibility

Hiroaki Hayashi, Yoshiki Mihara, Natsumi Kimoto, Takashi Asahara, Kenji Yamada, Yuki Kanazawa, Masafumi Harada, Tohru Okazaki and Takuya Hashizume :
Preliminary study for exposure dose measurement of people assisting during a pediatric X-ray procedure by means of a small-type OSL dosimeter,
European Congress of Radiology, Wien, Mar. 2017.

(要約): [Aims and objectives] During a pediatric X-ray procedure, medical staff or other people such as parents may assist to hold children during the X-ray examination. In this situation, these assistances are exposed by scattered X-rays, but there are no precise data concerning exposure doses. The aim of this study is to measure exposure dose of people assisting during the X-ray procedure. [Methods and materials] We used small-type OSL dosimeter (Landauer), which was sufficiently initialized. The detection limit of our system was estimated to be 0.5 micro-Gy. The OSL dosimeter was attached outside the lead protector which was worn by the assistant. In order to reduce contamination from background X- and/or gamma-rays, the exposed dosimeters were analyzed within 12 hours. The X-ray diagnostic system consisted of X-ray equipment and flat-panel detector which has auto-exposure control. The typical irradiation condition was SID=1.1 m, 3.2 mAs, and 53 kV. [Results] The exposure doses of assistances in the position outside the lead protector were approximately 3 micro-Gy. We measured 5 cases, in which patient's ages were 7 months to 1 year 6 months. Patient age showed no significant differences in exposure doses. [Conclusion] For the first time, using the small-type OSL dosimeter, we measured exposure dose of people assisting during a pediatric X-ray examination in a position outside the lead protector. The measured value was extremely low. Our actual data supports the justification of the situation in which someone should hold a child during an X-ray procedure.

Toshiaki Sasaki, Yuki Kanazawa, Yuki Matsumoto, Hiroaki Hayashi, Natsuki Ikemitsu, Takatoshi Usuda, Mitsuharu Miyoshi and Masafumi Harada :
T1 dependence of magnetization transfer effect for macromolecules,
European Congress of Radiology, Wien, Mar. 2017.

(要約): Purpose: To assess the relationship between T1 and magnetization transfer (MT) effect on macromolecules, we determined T1 map derived from variable flip angle (VFA) method with MT pulse. Materials and Methods: On a 3.0 T magnetic resonance (MR) system, we performed a phantom study using spoiled gradient-echo sequences; TR, 600 ms; TE, 5.8 ms; FA, 5, 20, 40, 60, and 90 degrees; without and with MT pulse (offset frequency, 800 ,1200 , and 1600 Hz). The phantom components were six samples; water and polyethylene glycol (PEG) solutions at different concentrations (10, 20, 30, 40, and 50 wt%). We calculated T1 maps from image datasets without and with MT pulse. Then, the MT ratio (MTR) maps were calculated from each FA image. Results: The mean T1 range without MT pulse for each sample was from 1200 to 2039 ms. The mean T1 ranges with MT pulse of each sample were from 1322 to 1886 at 800 Hz; from 1310 to 1926 ms at 1200 Hz; from 1300 to 1909 ms at 1600 Hz. The MTR of each sample showed the highest value at FA 5 degrees and offset 800 Hz. The mean MTR values of each sample were 6.54 ± 2.78, 3.94 ± 1.92, 2.50 ± 1.67, 1.96 ± 1.33, 1.44 ± 1.15, and 1.78 ± 1.53%. Conclusion: Determination of T1 with MT pulse makes it possible to obtain more detailed information of macromolecules.
(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2017/C-0827
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(DOI: 10.1594/ecr2017/C-0827) Natsuki Ikemitsu, Yuki Kanazawa, Yuki Matsumoto, Hiroaki Hayashi, Takatoshi Usuda, Toshiaki Sasaki, Mitsuharu Miyoshi and Masafumi Harada :
An improvement of signal-to-noise ratio for phase image,
European Congress of Radiology, Wien, Mar. 2017. Natsumi Kimoto, Hiroaki Hayashi, Takashi Asahara, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki and Masahiro Okada :
Development of a novel method based on a photon counting technique with the aim of precise material identification in clinical X-ray diagnosis,
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, Vol.10132, Florida, United States, Feb. 2017.

(出版サイトへのリンク): ● Publication site (DOI): 10.1117/12.2253564
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-85020383600

(DOI: 10.1117/12.2253564, Elsevier: Scopus) Hiroaki Hayashi, Takashi Asahara, Natsumi Kimoto, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki and Masahiro Okada :
Response functions of multi-pixel type CdTe detector, --- toward development of precise material identification in diagnosti x-ray images by means of photon counting ---,
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, Florida, United States, Feb. 2017.

(出版サイトへのリンク): ● Publication site (DOI): 10.1117/12.2251185
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-85020419621

(DOI: 10.1117/12.2251185, Elsevier: Scopus) Hiroaki Hayashi, Tohru Okazaki, Yoshiki Mihara, Kenji Yamada, Natsumi Kimoto, Kazuki Takegami, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Takuya Hashizume, Ikuo Kobayashi and Mary A. Kaila Ann Reginaldo :
Uncertainty estimation of dose measured with a small-type optically stimulated luminescence dosimeter for CT scanning, --- Basic study for estimating entrance skin dose and internal organ dose ---,
22nd International Conference on Medical Physics ICMP, Bangkok, Dec. 2016.

(要約): Purpose: In the diagnostic X-ray region, we have verified that a small-type optically stimulated luminescence (OSL) dosimeter can measure entrance-skin-dose (ESD) without consideration of energy and angular dependences if we adopted a systematic uncertainty of 15%. The aim of the present study is to estimate the uncertainty of the dose measured during X-ray CT scanning. During CT examinations, X-rays are collimated to a thin beam, therefore some X-rays directly irradiate the small dosimeter and other X-rays do not. These phenomena are related to the function of the beam width and distances between beams. Methods: Using a 320-rows CT scanner, phantom studies were performed. For estimating the accuracy of measuring the ESD, the OSL dosimeters and Gafchromic films were placed on the abdomen of the water phantom and irradiated simultaneously. Then, measured doses were compared. For estimating the accuracy of the internal dose measurement (organ dose), the OSL dosimeters were embedded in a hand-made acrylic phantom. Results: The ESDs measured with the OSL dosimeters and the Gafchromic films were consistent, and we found that the deviations of measured doses with OSL dosimeters from the averaged value were at most 25% under general irradiation conditions used during CT scanning. Conclusions: We summarized that research technicians should consider an additional 25% systematic uncertainty when a small-type OSL dosimeter is applied to measure the dose during CT scanning. An additional 25% uncertainty is slightly high, but in consideration we can reliably measure X-ray dose without consideration of placements of the dosimeters.

Tohru Okazaki, Hiroaki Hayashi, Hiroki Okino, Yoshiki Mihara, Takashi Asahara, Natsumi Kimoto, Yuki Kanazawa, Kazuki Takegami, Takuya Hashizume, Ikuo Kobayashi and Reginaldo A. Kaila Ann Mary :
Calculation of energy and angular dependences of the small-type OSL dosimeter in the diagnostic and nuclear medicine regions using the Monte-Carlo simulation code,
22nd International Conference on Medical Physics ICMP, Bangkok, Dec. 2016.

(要約): Purpose: The International Commission on Radiation Protection (ICRP) reviewed the threshold of the cataract, and recommended the new dose limits as 100 mSv / 5 y and 50 mSv / y. To estimate the eye lens dose, the small type optically stimulated luminescence dosimeter, nanoDot is expected to use. The aim of this study is to evaluate the angular and energy dependences of the nanoDot OSL dosimeter for the precise measurement of the eye lens dose. Method: Using the Monte-Carlo simulation code (electron gamma shower ver. 5: EGS5), the simplified OSL dosimeter was modeled. Then, taking account of the secondary electron equilibration, angular dependence of 0-360 degrees and energy dependence of 10 keV-2 MeV were calculated. Moreover, we performed experiments using the diagnostic X-ray equipment, and the obtained results were compared with the simulation. Results: In the diagnostic X-ray region, angular dependences were found to be almost flat except for 90 and 270 degrees (side directions), and these trends were in good agreement with the experiments. The energy dependence was defined as measured value divided by air-kerma. In this definition, rapid change was not observed in the energy region of 20 keV-2 MeV. Conclusions: In this study, we simulate the response of the small-type OSL dosimeter, nanoDot, using the Monte-Carlo simulation code. The nanoDot dosimeter was expected to be a proper dosimeter for the evaluation of the eye lens dose, especially caused by the scattered radiations in the medical diagnosis.

Tohru Okazaki, Hiroaki Hayashi, Yoshiki Mihara, Natsumi Kimoto, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Kazuki Takegami, Takuya Hashizume, Ikuo Kobayashi and Reginaldo A. Kaila Ann Mary :
Universal dose calibration of the small-type OSL dosimeter for diagnostic X-rays - direct, scattered and penetrating X-rays -,
22nd International Conference on Medical Physics ICMP, Bangkok, Dec. 2016.

(要約): Purpose: The small type optically stimulated luminescence dosimeter, nanoDot is expected to apply to the evaluation of eye lens dose. Dose calibration of nanoDot is carried out by the air kerma of the X-ray, however the main component of eye lens exposure is scattered X-ray in the medical field. Therefore we evaluated the reliability of the dose calibration of nanoDot dosimeter in different quality of X-rays. Method: The main calibration line was determined by the air-kerma of 83 kV X-rays in dose range of 4 Gy to 2 mGy. In addition, to evaluate the reliability of the calibration line in different X-ray qualities, the response of nanoDots were compared with the air kerma of scattered X-ray and penetrated X-ray, and/or entrance skin dose. In the same manner, 55 and 108 kV X-rays were irradiated. Then the differences between the main calibration and other data were evaluated. Results: The measured data of each conditions were in good agreement with the main calibration line derived by the air kerma of 83 kV X-ray. Even in 4 Gy irradiated dosimeters, most of the results were in inside of +/-15% deviations from the calibration line. Conclusions: In this study, we evaluated the reliability of the calibration of the small-type OSL dosimeter, nanoDot. The nanoDot calibrated by the air kerma of 83 kV X-ray can be applied to the air kerma of scattered X-ray and penetrated X-ray and/or entrance skin dose of diagnostic X-rays when we adopt 15% systematic uncertainty.

Yuki Matsumoto, Yuki Kanazawa, Nattsuki Ikemitsu, Toshiaki Sasaki, Hiroaki Hayashi, Mitsuharu Miyosh, Masafumi Harada and Hideki Otsuka :
Proposal of an appropriate echo time-input function for quantitative susceptibility mapping.,
International Conference On Medical Physics (ICMP) 2016, Bangkok, Dec. 2016.

(要約): Purpose To improve the quantitative assessment for both diamagnetic and paramagnetic materials, we developed a quantitative susceptibility mapping (QSM) method using an appropriate echo time (TE)-input function. Methods On 3.0 T MR system, we performed a phantom experiment using a multi-echo spoiled gradient-echo (12 echos; delta TE = 4.4 ms). The phantom consisted of gadopentetate dimeglumine (Gd-DTPA) and hydroxyapatite samples, which were made using three different concentrations of each material. After a multiple TE dataset was acquired, T2* values were calculated from the dataset. When a field map estimation was computed, the appropriate T2* value was used as TE-input function. Next, phase unwrapping and background removal were performed. Finally, the reconstruction of QSM was performed. Moreover, we compared susceptibility values derived from TE-input function and conventional methods. Results The mean T2* values of each Gd-DTPA and hydroxyapatite sample were 365 ± 74, 194 ± 9, 86 ± 3, 24 ± 2, 14 ± 1, and 11 ± 1 ms, respectively. Compared with the conventional method, the proposed TE-input function method indicated good positive linearity for the relationship between the Gd-DTPA concentration and susceptibility (slope = 0.26 ppm/mmol/L, R2 = 0.97, P = 0.11). Additionally, the proposed TE-input function method indicated good negative linearity for the relationship between the concentration and hydroxyapatite susceptibility (slope = -0.0019 ppm/mg/mL, R2 = 1.00, P = 0.02). Conclusions QSM with the TE-input function makes it possible to evaluate simultaneously diamagnetic and paramagnetic materials. e.g. Gd-DTPA and hydroxyapatite.
(キーワード): quantitative susceptibility mapping (QSM); field map estimation; echo time; T2* mapping.

Natsumi Kimoto, Hiroaki Hayashi, Takashi Asahara, Yoshiki Mihara, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki and Masahiro Okada :
Basic study for material identification toward development of a next generation type X-ray diagnosis detector based on a photon counting technique,
22nd International Conference on Medical Physics ICMP, Bangkok, Dec. 2016.

(要約): Purpose: X-ray diagnosis is widely used for obtaining medical images. Recently, a photon counting system has been developed and applications for X-ray imaging are expected to be developed. One of the advantages for applying the photon counting is to obtain new information about material identification in the medical image. The aim of this study is to propose a novel method for material identification. Methods: Assuming that a CdTe detector measures one pixel of a two-dimensional imaging detector, the following experiments were performed. First, 40 kV X-rays generated with diagnostic X-ray equipment were measured. Second, four different phantoms (soft-tissue equivalent, bone-equivalent, acrylic, aluminum) were placed in front of the CdTe detector and the X-ray spectra penetrating the phantoms were measured. Then, the measured spectra were divided into two regions, and analyzed by our method. At this time, the beam hardening effects in the measured spectra were corrected. Finally, effective atomic numbers were determined and compared with theoretical values. Results: Our method works well to identify the four different materials by analyzing the measured X-ray spectra. The relationship between accuracy of determined effective atomic numbers and statistics of measured X-ray spectra was evaluated. Then we found the possibility to establish the accuracy of +/-0.1 in atomic number using our method. Conclusions: For developing a next generation type medical imaging system using a photon counting technique, we proposed a novel method in which an effective atomic number can be determined. The detailed analysis concerning the vision of clinical application is now in progress.

Yuki Matsumoto, Yuki Kanazawa, Hiroaki Hayashi, Kazuki Takegami, Tsuyoshi Matsuda, Masafumi Harada and Hideki Otsuka :
How do you Determine the Echo Time When Calculation of Quantitative Susceptibility Mapping (QSM)?,
Radiological Society of North America (RSNA) 2016, Chicago, Dec. 2016.

(要約): TEACHING POINTS The purpose of this exhibit is to learn that 1. It is important to know dependence of signal loss due to T2* decay, corresponding to echo time (TE) and susceptibility of biomaterial. 2. Magnetic susceptibility have paramagnetic and diamagnetic characterization, i.e., these indicate positive and negative values, respectively. TABLE OF CONTENTS/OUTLINE -Aims The aim of our study is to investigate the difference in magnetic susceptibility for various TEs. -Method On a 3.0 T MR system, we performed a phantom experiment. The phantom consisted of Gd-DTPA and hydroxyapatite samples which were made using three different concentrations of each. In order to investigate the difference in the magnetic susceptibility of each TE, multiple TEs were acquired and several TE datasets were made. Then, we analyzed with each dataset. -Results The TEs = 3.1, 7.5 and 11.9 ms datasets indicated highest positive linearity for the Gd-DTPA samples (slope = 0.244, R2 = 0.998, P = 0.021). Moreover, the TEs = 3.1, 7.5 and 11.9 ms datasets indicated highest negative linearity for the hydroxyapatite samples (slope = -0.001, R2 = 0.997, P = 0.035). -Conclusion QSM makes it possible to accurately calculation of magnetic susceptibility by using the appropriate TE.

Yuki Kanazawa, Yuki Matsumoto, Nattsuki Ikemitsu, Toshiaki Sasaki, Hiroaki Hayashi, Kazuki Takegami, Tsuyoshi Matsuda and Masafumi Harada :
Hybrid assessment of gadopentetic acid and bone structure with ultrashort echo time imaging,
International Conference On Medical Physics (ICMP) 2016, Bangkok, Dec. 2016.

(要約): Purpose To clarify the phase cycles of Gd-DTPA and calcium carbonate (CaCO3), we evaluated the quantitative susceptibility map (QSM) for dual-ultrashort echo time (UTE) imaging in a phantom experiment. Materials and Methods On a 3.0 T MR system, we performed a phantom study using a three-dimensional dual UTE sequence (TE, 32 µs and 3.2 ms). The phantom components were made from different concentrations of a Gd-DTPA solution (0.1, 0.5, and 1 wt%) and CaCO3 sections. The QSM algorithm was applied to the dual (32 µs and 3.2 ms) and single (32 µs) UTE datasets. We then set the region-of-interest for each material section on QSM images, and measured susceptibility values. Furthermore, linear regression analyses were used to determine the significance between Gd-DTPA concentration and susceptibility for each TE dataset. Results The mean susceptibility value of CaCO3 calculated from the dual UTE showed 1.09 ± 0.35 ppm. Additioally, the mean susceptibility values of 0.1, 0.5, and 1.0 wt% Gd-DTPA calculated from the dual UTE were -0.14 ± 0.03, -0.61 ± 0.02, and -1.24 ± 0.03 ppm. Moreover, there was a negative correlation between Gd-DTPA concentration and susceptibility derived from dual UTE (R2 = 0.9995, P = 0.0141). In contrast, there was no correlation between these values derived from single UTE (R2 = 0.00157, P = 0.9747). Conclusion QSM using dual UTE imaging makes it possible to simultaneously evaluate Gd-DTPA and CaCO3, i.e., bone tumor imaging with contrast-enhanced MRI.
(キーワード): magnetic resonance image (MRI); ultrashort echo time (UTE); susceptibility; bone tumor

Kazuki Takegami, Hiroaki Hayashi, Natumi Kimoto, Yoshiki Mihara, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Fumio Hayashi, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Universal calibration curve for a small-type OSL dosimeter to be used for direct dose measurements of direct, scattered and penetrating X-rays in the diagnostic region,
Radiological Society of North America (RSNA), Chicago, Dec. 2016.

(要約): (1)Aims: We hope to find a suitable dosimeter, which can measure incident, scattered and penetrating X-rays. In this study, we propose a new procedure to calibrate the OSL dosimeter. (2)Experiment & results: Initially, we constructed a calibration curve of air-kerma (direct X-rays) with comparison between the OSL dosimeter and an ionization chamber. Second, we evaluated the accuracy of the above calibration curve when the following conditions were applied; 1) entrance-skin dose, and 2) air-kerma of scattered X-rays and 3) penetrating X-rays through a soft-tissue equivalent phantom. We then found that the above calibration curve can be used in all situations if we adopt 15% of uncertainty. Finally, the X-ray spectra related to those conditions were measured, and with the data on basic characteristics of the dosimeter, the result of 15% uncertainty was verified mathematically. (3)Conclusion: With 15% uncertainty, we can use the OSL dosimeter without considerations of energy dependence, angular dependence etc. This study enabled the OSL dosimeter to manage the exposure dose of medical staff, assistants and patients.

Hiroaki Hayashi, Kazuki Takegami, Kenji Yamada, Yoshiki Mihara, Natsumi Kimoto, Yuki Kanazawa, Kousaku Higashino, Yamashita Kazuta, Fumio Hayashi, Yoshihiro Fukui, Koichi Sairyo, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Convenient measurement method using small-type OSL dosimeters for evaluation of doses in CT scans: uncertainty evaluation, entrance-skin dose of phantom, and organ dose of cadaver,
Radiological Society of North America (RSNA), Chicago, Dec. 2016.

(要約): (1)Aims Because the OSL dosimeter used in this research is small in size, when the dosimeters are attached to the patients, it should be considered that certain dosimeters are directly irradiated by the collimated X-ray beam and others are not. (2)Experiments First, we investigated the precision and accuracy of the OSL dosimeters as functions of ``number of detectors (rows)'' and ``pitch factor'' using a CT scanner. In this experiment, the true entrance skin doses (ESDs) and its distribution of a water phantom was measured with Gafchromic film. (3)Results & Discussion We estimated that OSL dosimeters can measure doses within an uncertainty of 25% for most irradiation conditions. Additionally, we demonstrated the application of dose measurements using the OSL dosimeters; 1) ESDs of a body phantom were measured, and 2) organ doses of a cadaver were directly determined for the first time. These data are valuable for the education of dose reductions. Our method using the OSL dosimeter is convenient, therefore everyone can share our results for improvement of clinical CT examinations.

Yuki Kanazawa, Yuki Matsumoto, Hiroaki Hayashi, Tsuyoshi Matsuda, Manguu Ganbold and Masafumi Harada :
Simple improvement method of uniformity of MR elastography on liver,
ISMRM 24th Annual Meeting, 2972, Singapore, May 2016. Tohru Okazaki, Hiroaki Hayashi, Kazuki Takegami, Yoshiki Mihara, Natsumi Kimoto, Yuki Kanazawa, Takuya Hashizume and Ikuo Kobayashi :
Small size OSL dosimeter to measure patient exposure dose in X-ray diagnosis - Evaluation of invisibility -,
14th international congress of the international radiation protection association, cape town, May 2016. Yuto Konishi, Yuki Kanazawa, Takatoshi Usuda, Yuki Matsumoto, Hiroaki Hayashi, Tsuyoshi Matsuda and Masafumi Harada :
Comparison with statistical analysis of signal correction in diffusion weighted MR image,
European Congress of Radiology (EPOS), Wien, Mar. 2016. Hiroaki Hayashi, Natsumi Kimoto, Hiroki Okino, Itsumi Maehata, Kazuki Takegami and Yuki Kanazawa :
Development of leaf electroscope to understand ionization for novice practical training,
European Congress of Radiology, 2016, Wien, Mar. 2016. Hiroki Okino, Hiroaki Hayashi, Kazuki Takegami, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Compact irradiation system for evaluation of basic characteristics of the nanoDot OSL dosimeter toward direct measurement of exposure dose of patients,
European Congress of Radiology, 2016, Wien, Mar. 2016. Yuki Kanazawa, Konishi Yuto, Usuda Takatoshi, Yuki Matsumoto, Hiroaki Hayashi, Matsuda Tsuyoshi and Masafumi Harada :
Noise estimation for diffusion weighted MR image,
European Congress of Radiology (EPOS), Vienna, Mar. 2016. Tohru Okazaki, Takuya Hashizume, Hiroaki Hayashi, Kazuki Takegami, Hiroki Okino, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa and Kobayashi Ikuo :
Evaluation of energy dependence of nanoDot optically stimulated luminescence (OSL) dosimeter using characteristic X-ray induced by medical X-ray equipment,
European Congress of Radiology (General&Voice of EPOS), 2016, Wien, Mar. 2016. Itsumi Maehata, Hiroaki Hayashi, Natsumi Kimoto, Hiroki Okino, Kazuki Takegami and Yuki Kanazawa :
Precise determination of the scattered X-ray contamination rate using diagnostic X-ray equipment for the construction of the secondary X-ray field,
European Congress of Radiology, 2016, Wien, Mar. 2016.

(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0007
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0007

(DOI: 10.1594/ecr2016/C-0007) Natsumi Kimoto, Hiroaki Hayashi, Hiroki Okino, Kazuki Takegami, Itsumi Maehata, Yuki Kanazawa, Tsutomu Yamakawa and Shuichiro Yamamoto :
Fabrication and analysis of phantoms providing the equal-image-density for basic experiment of next-generation-type X-ray diagnosis,
European Congress of Radiology, 2016, Wien, Mar. 2016.

(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0012
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0012

(DOI: 10.1594/ecr2016/C-0012) Kazuki Takegami, Hiroaki Hayashi, Hiroki Okino, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi :
Proposal of quantitative identification method of a small-type OSL dosimeter: Verification that the dosimeter is not detected in the medical image,
European Congress of Radiology (General&Voice of EPOS), 2016, Wien, Mar. 2016.

(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2016/C-0010
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2016/C-0010

(DOI: 10.1594/ecr2016/C-0010) Hiroaki Hayashi, Hiroki Okino, Kazuki Takegami, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tsutomu Yamakawa and Shuichiro Yamamoto :
Experimental evaluation of response functions of a CdTe detector in the diagnostic region with the aim of carrying out a basic experiment concerning a next generation photon counting system,
European Congress of Radiology, 2016, Wien, Mar. 2016. Hiroaki Hayashi, Kazuki Takegami, Hiroki Okino, Natsumi Kimoto, Itsumi Maehata, Yuki Kanazawa, Tohru Okazaki and Ikuo Kobayashi :
Precise measurement of the angular and energy dependences of small-type OSL dosimeter in the diagnostic energy region,
RSNA2015, Education Exhibits, Chicago, Nov. 2015. Hiroaki Hayashi, Natsumi Kimoto, Itsumi Maehata, Kazuki Takegami, Hiroki Okino, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki and Masahiro Okada :
A Fundamental Experiment for Novel Material Identification Method Based on a Photon Counting Technique: Using Conventional X-Ray Equipment (PosNo=M3CP-125),
IEEE Nuclear Science Symposium & Medical Imaging Conference, San Diego, Oct. 2015.

(出版サイトへのリンク): ● Publication site (DOI): 10.1109/NSSMIC.2015.7582027
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-84994106012

(DOI: 10.1109/NSSMIC.2015.7582027, Elsevier: Scopus) Yuki Kanazawa, T. Miyati, Hiroaki Hayashi, A. Yagi and O. Sato :
Optimization of imaging parameter in contrast-enhanced three-dimensional T1 weighted MRI with fat saturation for head disease,
European Congress of Radiology 2015 (EPOS), Wien, Mar. 2015.

(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2015/C-1450
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2015/C-1450

(DOI: 10.1594/ecr2015/C-1450) Hiroaki Hayashi, Kazuki Takegami, Hiroki Okino, Kohei Nakagawa and Yuki Kanazawa :
Development of new educational apparatus to visualize scattered X-rays,
European Congress of Radiology 2015 (EPOS), Wien, Mar. 2015.

(出版サイトへのリンク): ● Publication site (DOI): 10.1594/ecr2015/C-0073
(文献検索サイトへのリンク): ● Search Scopus @ Elsevier (DOI): 10.1594/ecr2015/C-0073

(DOI: 10.1594/ecr2015/C-0073) M. T. Mehemed, Y Fushimi, T Okada, A Yamamoto, M Kanagaki, E Morimoto, R Sakamoto, S Nakajima, S Okuchi, H Yamada, T Kakigi, A Sakata, T Dodo, Yuki Kanazawa, K Takakura, K Fujimoto, A Kido, N Sakashita and K Togashi :
Dynamic Oxygen-Enhanced MRI of Cerebro-Spinal Fluid: Inversion Recovery Fast Advanced Spin Echo (IR-FASE) Vs. FASE.,
Annual Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRM2013), Toulouse, Oct. 2013. Y Fushimi, T Okada, A Yamamoto, M Kanagaki, M. T. Mehemed, E Morimoto, R Sakamoto, S Nakajima, S Okuchi, H Yamada, T Kakigi, A Sakata, T Dodo, Yuki Kanazawa, K Takakura, K Fujimoto, A Kido, N Sakashita and K Togashi :
Comparison between Proton MR spectroscopy and MIB-1 labeling index of brain tumors,
Annual Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRM2013), Toulouse, Oct. 2013. Yuki Kanazawa, T Miyati, O Sato and J Tazoe :
Why do we have to calculate T₁ when evaluation of carotid plaque?,
ECR2011, Wien, Mar. 2011. Yuki Kanazawa, T Miyati and O Sato :
Hemodynamics Quantitative Analysis of Urinary Bladder Tumor,
RSNA2009, Chicago, Nov. 2009. Yuki Kanazawa, T Miyati and O Sato :
Why Do We Have to Calculate T₁ Value when Evaluation of Urinary Bladder Tumor?,
RSNA2008, Chicago, Nov. 2008. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Taniguchi Yo and Ono Masaharu :
Basic Considerations for the Development of Gadolinium Contrast Agents with High pH Sensitivity,
JSMRM2024, Sep. 2024. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Taniguchi Yo and Ono Masaharu :
Development of Extracellular pH Mapping Method using Quantitative Parameter Mapping(QPM)and Gadolinium-based Contrast Agents,
JSMRM2024, Sep. 2024. 大城隆嗣, 金澤裕樹, 芳賀昭弘, 原田雅史 :
生体構造解析を目的としたMR信号数値ファントムの開発,
第80回日本放射線技術学会総会学術大会, 2024年4月. 瀬口真友香, 金澤裕樹, 宮地利明, 原田雅史, 三好光晴, 林裕晃, 芳賀昭弘 :
粘稠度導出法を用いたアテローム性動脈硬化症の臨床検討,
第80回日本放射線技術学会総会学術大会, 2024年4月.

(要約): 【目的】拡散係数と粘稠度の関係は線形性を示すことが知られているが，以前に我々が開発した粘稠度算出手法は課題を残した．本研究の目的は，拡散強調画像(DWI)を用いて粘稠度を導出する手法を改良し，アテローム性動脈硬化症のプラークの物性を評価することである．【方法】本研究は，3テスラMRI装置を用いて検討を行った．ファントム実験は，濃度の異なるグリセリン水溶液(20–60%)を作成し，恒温水槽内を37 ℃の状態にして粘稠度を計測した．各濃度の水溶液からファントムを作成し，エコープラナー法を用いて DWI を撮像した．撮影パラメータは，繰り返し時間(TR)，10000 ms;エコー時間(TE)，63.5 ms;b値，0–1500 s/mm2 に設定した．DWI の信号値を単一指数関数モデルで曲線近似し，ADC を算出した．実測した水溶液の粘稠度と ADC の関係を直線近似により粘稠度関数を導出した．臨床検討は，頸動脈内膜剥離術(CEA)が施行され，粥腫形成ありと病理診断された頸動脈狭窄症患者(27名:平均年齢74±6.2歳)の DWI を撮像した．撮影パラメータは，TR，3000 ms;TE，52.1 ms;b値，0，250，500 s/mm2に設定した．ファントム実験と同様に，DWI の信号値から算出した ADC 値を粘稠度関数に当てはめ粘稠度を求め可視化した．各症例群間の粘稠度を比較した．【結果】グリセリン水溶液の粘稠度は，濃度により粘稠度が高値になった．ファントムのDw-MRIから算出した粘稠度の算出式は，y=-0.79x+2.94 となった．ここで，y は粘稠度，x はADCとする．臨床検討において，全症例の平均 ADC 値は，1.72 ± 0.489 [× 10-3 mm2/s]，平均粘稠度値は 0.003 ± 0.386 [µPa·s] となった．症候性および出血の有無で粘稠度を比較すると有意な差があった(P < 0.05および < 0.01)．

兼松康久, 金澤裕樹, 島田健司, 高麗雅章, 曽我部周, 石原学, 山口泉, 羽星辰哉, 山本伸昭, 黒田一駿, 原田雅史, 髙木康志 :
CEST MRIを用いた頚動脈プラーク診断,
STROKE 2024, 2024年3月. 富永羽香, 金澤裕樹, 三好光晴, 原田雅史 :
CEST イメージングの高分子濃度と pH 緩衝液依存性の検討,
第51回日本放射線技術学会秋季学術大会, 2023年10月. 金澤裕樹 :
臨床実現を目指したMR脳機能イメージング研究,
第51回日本放射線技術学会秋季学術大会, 2023年10月. 龍ケ江千香, 金澤裕樹, 福田和海, 原田雅史 :
4D-flow MRIから導出した流体パラメータと頸動脈狭窄率の関係,
第51回日本放射線技術学会秋季学術大会, 2023年10月. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa and Miyoshi Mitsuharu :
AcidoCEST contrast media exhibiting pH dependence on a 3T clinical MRI system,
JSMRM2023, Sep. 2023. 瀬口真友香, 金澤裕樹, 宮地利明, 松元友暉, 原田雅史, 林裕晃, 芳賀昭弘 :
アテローム性動脈硬化症におけるプラーク性状評価のための粘稠度MRI,
第 79 回日本放射線技術学会総会学術大会, 2023年4月. 魚谷俊介, 金澤裕樹, 大城隆嗣, 芳賀昭弘, 原田雅史 :
最尤推定を用いたMyelin Water Fraction導出法の検討,
第 79 回日本放射線技術学会総会学術大会, 2023年4月. 瀬口真友香, 金澤裕樹, 芳賀昭弘, 原田雅史 :
アテローム性動脈硬化症におけるプラーク形成の潜在的危険因子の評価,
第50回日本放射線技術学会秋季学術大会, 2022年10月. 魚谷俊介, 金澤裕樹, 大城隆嗣, 芳賀昭弘, 原田雅史 :
信号雑音比を考慮したMyelin Water Fraction導出法の開発,
第50回日本放射線技術学会秋季学術大会, 2022年10月. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Quantitative parameter mapping of brain tumor extracellular pH for therapeutic efficacy,
ISMRM Japanese Chapter, Sep. 2022. Yuki Matsumoto, Masafumi Harada, Monda Kanon, Yuki Kanazawa, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Development of a neural network based skull stripping algorithm for quantitative parameter mapping both before and after injection of contrast media,
JSMRM2022, Sep. 2022. 土師正太郎, 藤田浩司, 沖良祐, 大崎裕亮, 金澤裕樹, 松元友暉, 有澤亜津子, 川井恒, 佐藤康敬, 八木健太, 坂口暁, 楊河宏章, 濱谷辰斗, 長野清一, 望月秀樹, 熱田直樹, 道勇学, 祖父江元, 原田雅史, 和泉唯信 :
EPI-589の筋萎縮性側索硬化症を対象とした探索的医師主導試験(EPIC-ALS),
第63回日本神経学会学術大会, 2022年5月. 松元友暉, 原田雅史, 金澤裕樹, 三好光晴 :
3T-MRI装置におけamide-proton transfer イメージングの臨床有用性,
第12回日本安定同位体生体ガス医学応用学会, 2021年12月. 林裕晃, 前田達哉, 淺原孝, 後藤聡汰, 竹上和希, 李青海, 安藤未来, 金澤裕樹, 生島仁史, 岡崎徹, 橋詰拓弥 :
ディスポ型自作直腸線量計を用いた子宮頸がん治療における線量の実測,
第3回日本放射線安全管理学会・日本保健物理学会合同大会, 2021年12月. 兼松康久, 金澤裕樹, 島田健司, 曽我部周, 宮本健志, 石原学, 四方英二, 山口泉, 多田恵曜, 山本雄貴, 山本伸昭, 原田雅史, 髙木康志 :
CEST MRIを用いた頚動脈プラーク診断 Chemical exchange saturation transfer MRI for carotid plaque imaging,
NMC Case Report Journal, 2021年10月. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa and Miyoshi Mitsuharu :
A pilot study of extracellular pH measurement using iopamidol acido-chemical exchange transfer imaging on a 3T MRI,
JSMRM2021, Sep. 2021. 福田和海, 金澤裕樹, 松元友暉, 北野舜, 芳賀昭弘, 原田雅史 :
VFA法における多変量正規分布の確率密度関数を用いたB1補正手法の提案,
第49回日本磁気共鳴医学会大会, 2021年9月. 池光捺貴, 金澤裕樹, 原田雅史, 松元友暉, 伊藤公輔, 谷口陽, 尾藤良孝, 芳賀昭弘 :
白質領域に対する非剛体処理に伴う数値解析の影響,
第49回日本磁気共鳴医学会大会, 2021年9月. 北野舜, 金澤裕樹, 原田雅史, 松元友暉, 福田和海, 林裕晃, 谷口陽, 芳賀昭弘 :
Myelin Water Fraction(MWF)におけるT2* cut-off値の検討,
第49回日本磁気共鳴医学会大会, 2021年9月. 鴻野まどか, 内田貴之, 大石あかね, 平山楓子, 竹村祐馬, 髙尾正一郎, 金澤裕樹, 松元友暉, 原田雅史, 榊原伊織, 鈴木利雄, 二川健 :
蒸し大豆食品の継続摂取が運動不足の健常人の筋量や筋力に及ぼす影響,
第75回日本栄養・食糧学会大会, 2021年7月. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
腫瘍悪性度の定量に向けた造影剤濃度，緩和能，細胞外pHの同時算出手法の開発,
日本分子イメージング学会, May 2021. Higuchi Takayuki, Akihiro Haga and Yuki Kanazawa :
Estimation of CT X-ray spectrum from reconstructed images using a deep neural network,
第121回日本医学物理学会, Apr. 2021. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Automatic detection of extracellular pH change in brain tissue using deep learning based semantic segmentation,
Japanese Journal of Radiological Technology, Apr. 2021. 北野舜, 金澤裕樹, 松元友暉, 福田和海, 佐々木健太, 芳賀昭弘, 原田雅史 :
T₂値およびT₂^*値導出に係るMyelin Water Fraction(MWF)値の影響,
第77回日本放射線技術学会総会学術大会, 2021年4月. 福田和海, 金澤裕樹, 松元友暉, 北野舜, 佐々木健太, 芳賀昭弘, 原田雅史 :
可変フリップアングル法を用いたT1値算出における線形近似と非線形近似の比較,
第77回日本放射線技術学会総会学術大会, 2021年4月. 金澤裕樹, 前田直輝, 原田雅史, 谷口陽, 松元友暉, 阿部考志, 林裕晃, 伊藤公輔, 尾藤良孝, 芳賀昭弘 :
Quantitative Parameter Mapping(QPM) を用いたコンポーネント間スピン交換定数の導出,
第48回日本磁気共鳴医学会大会Web開催, 2020年9月. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Which contrast agent is more sensitive to extracellular pH change on brain tumor ?,
JSMRM2020, Sep. 2020. 隅田奈美, 原田雅史, 河野理, 松元友暉, 金澤裕樹, Gonchigsuren Oyundari, 藤田浩司 :
運動異常症の安静時 fMRIにおける脳機能ネットワークの検討,
第48回日本磁気共鳴医学会大会Web開催, 2020年9月. Yuki Kinjo, Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Yuki Matsumoto, Takashi Abe, Hiroaki Hayashi, Masaharu Ono, Yoshitaka Bito and Akihiro Haga :
Spatially smoothing processing of quantitative values in voxel-based morphometry (VBM) analysis,
第76回日本放射線技術学会総会学術大会WEB開催, May 2020. Takashi Asahara, Hiroaki Hayashi, Tatsuya Maeda, Yuki Kanazawa, Satoshi Imajo, Miho Numata and Mitsugi Honda :
Dual-type active dosimeter having a novel algorithm to identify incident angles of X-rays,
第76回日本放射線技術学会総会学術大会WEB開催, May 2020. 長谷川侑, 芳賀昭弘, 坂田洞察, 金澤裕樹, 富永正英, 佐々木幹治, 今江禄一, 中川恵一 :
Estimation of X-ray energy spectrum for CT scanner from percentage depth dose measurement,
第119回⽇本医学物理学会学術⼤会WEB開催, 2020年5月. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Simultaneous Quantitative Calculation of Concentration of Contrast Agent, Relaxivity, and Extracellular pH Map,
Japanese Journal of Radiological Technology, Apr. 2020. Goto Sota, Hayashi Hiroaki, Tomita Emi, Asahara Takashi, Ikushima Kaho, Kuwabara Momoka and Yuki Kanazawa :
Phantom study using novel shaped OSL dosimeters having smaller angular dependence toward actual dose measurement during clinical X-ray examination,
第76回日本放射線技術学会総会学術大会, 2020. 松元友暉, 金澤裕樹, 金城祐奎, 原田雅史, 阿部考志, 兼松康久, 髙木康志 :
頸動脈狭窄の定量評価を目的とした4D-flow流体解析,
第1回 4D FLOW研究会, 2019年9月. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Calculation of extracellular pH using quantitative parameter mapping,
JSMRM2019, Sep. 2019. Yuki Kinjo, Yuki Kanazawa, Masafumi Harada, Yo Taniguchi, Yuki Matsumoto, Takashi Abe, Hiroaki Hayashi, Masaharu Ono, Yoshitaka Bito and Akihiro Haga :
Comparison of estimation parameters of relaxation rate and susceptibility for myelin content with quantitative parameter mapping,
JSMRM2019, Sep. 2019.

(要約): To evaluate myelin content derived from QPM, we compared relaxation rate and susceptibility using simultaneously acquired imaging datasets. The relaxation rate and susceptibility derived from QPM enabled us to simultaneously and specifically evaluate structural changes and brain iron homeostasis.

紀本夏実, 林裕晃, 淺川巧, 淺原孝, 前田達哉, 金澤裕樹, 勝又明敏, 山本修一郎, 岡田雅宏 :
医療用連続X線を用いたフォトンカウンティング検出器による実効原子番号画像,
第2回量子線イメージング研究会, 2019年9月. 下窪康史, 櫻川加奈子, 冨田恵美, 林裕晃, 金澤裕樹, 生島仁史 :
子宮頸癌RALSにおける自作直腸線量計を用いた実臨床データとその分析,
日本放射線腫瘍学会小線源治療部会第21回学術大会, 2019年5月. 冨田恵美, 林裕晃, 淺原孝, 下窪康史, 櫻川加奈子, 金澤裕樹, 生島仁史 :
子宮頸癌の腔内照射における直腸線量実測に向けたディスポーザブル型直腸線量計の開発,
日本放射線腫瘍学会小線源治療部会第21回学術大会, 2019年5月. 金澤裕樹, 原田雅史, 谷口陽, 林裕晃, 阿部考志, 大友真姫, 松元友暉, 小野順玄, 尾藤良孝, 芳賀昭弘 :
Quantitative Parameter Mappingを用いたミエリンMRI,
第75回日本放射線技術学会総会学術大会, 2019年4月. Asahara Takashi, Hayashi Hiroaki, Mihara Yoshiki, Tomita Emi, Yuki Kanazawa, Yamada Kenji and Okazaki Tohru :
Actual Dose Measurement of Assistants while Positioning Patients during Pediatric X-ray Examination Using a Small-type Optically Stimulated Luminescence Dosimeter,
第75回放射線技術学会総会学術大会, Apr. 2019. Mihara Yoshiki, Hayashi Hiroaki, Uehara Takumi, Tada Keiji, Yuki Kanazawa, Okazaki Tohru and Kajitani Takafumi :
An experiment toward proposing a way to reduce eye lens exposure dose using small-type OSL dosimeter during neonatal cardiac CT examination,
第75回放射線技術学会総会学術大会, Apr. 2019. Sota GOTO, Hiroaki HAYASHI, Emi TOMITA, Takumi UEHARA, Yuki Kanazawa, Tohru OKAZAKI and Takuya HASHIZUME :
Trial production and evaluation of characteristics of novel-shaped optically stimulated luminescence dosimeter having lower angular dependence,
第75回放射線技術学会総会学術大会, Apr. 2019. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Takashi Abe, Maki Ohtomo, Taniguchi Yo, Ono Masaharu and Bito Yoshitaka :
Calculation of molar relaxivity and concentration map of Gd-DTPA map using quantitative parameter map before and after injection for brain metastasis,
ISMRM Japanese Chapter, Dec. 2018. 岡崎徹, 林裕晃, 後藤聡汰, 淺原孝, 冨田恵美, 金澤裕樹, 橋詰拓弥, Cruz Vergil, Hsin Wei Cheng :
小型OSL線量計の診断用X線に対する応答のエネルギー依存性の精密評価,
日本放射線安全管理学会第17回学術大会, 2018年12月. 長澤良子, 金澤裕樹, 金城佑奎, 千葉大輝, 原田雅史, 林裕晃, 松元友暉, 芳賀昭弘 :
硬さの検出を目的としたIntravoxel Incoherent Motion(IVIM)を用いた曲線解析モデルの比較,
第46回日本放射線技術学会秋季学術大会, 2018年10月.

(要約): 【目的】拡散強調画像(DWI)から生体の硬さを推定するために，intravoxel incohernet motion(IVIM)手法を用いた3つの曲線解析手法を評価した．【方法】 1.5テスラMRI装置(GE社製)にて，ファントム実験を行なった．ファントムは，異なる濃度のagar(0.75，1.0，1.5，2.0wt%)をアクリルボックスの中に配列し，1 wt%のagarで満たした．DWIはsingle shot echo planner imagingを用いて，複数のb値(0，20，50，100，200，400，600，800，1000，1200，1500 s/mm2)に設定し撮像した．MR elastography(MRE)はMR touchを用いて，ドライバー周波数120 Hzに設定し撮像した．DWIは，関心領域を各サンプル内に設定し，各b値の信号値を取得した後，mono-exponential, bi-exponential, stretched-exponentialモデルを用いて曲線解析を行い，各種パラメータ(ADC，f，D*，D，DDC，α)を算出した．このとき，MREのせん弾性率とDWIから取得した各種パラメータを比較した．【結果】 MREから算出した0.75，1.0，1.5，2.0 wt%ファントムのせん弾性率は，6.5，10.6，30.8，40.0 kPaであった．bi-exponentialモデルから算出したD*は，MREのせん弾性率と負の相関を示した(r = 0.57)．stretched-exponentialモデルから算出したα値は，MREのせん弾性率と負の相関を示した(r = 0.80)．【結論】 stretched exponential モデルを用いた拡散解析は，生体内の組織の硬さを測定するのに有用な手法である．

千葉大輝, 金澤裕樹, 金城佑奎, 長澤良子, 三好光晴, 林裕晃, 原田雅史, 芳賀昭弘 :
CESTイメージングにおける局所オフセット周波数の定量評価法の開発,
第46回日本放射線技術学会秋季学術大会, 2018年10月.

(要約): 【目的】この研究の目的は，CEST画像における局所のオフセット周波数を定量的に評価することである．【方法】 3テスラMRI装置(GE社製)にて，CESTイメージングを用いてファントム実験を行った．アクリルボックスの底にプラスチックを格子状に配列し，アルブミン水溶液(45 g/L)を封入したファントムを作成した．CESTイメージングの撮像シーケンスはsingle shot fast spin-echo法を使用し，オフセット周波数帯域，±7 ppm(Δ0.5 ppm); 最大B1，5.16 μTに設定した．オフセット周波数補正ありと無しのデータセットを取得した．MTパルスを付加しない画像(S0)と，各オフセット周波数(1，2，3.5 ppm)の画像に対して，ファントムの中心部および辺縁部の格子に関心領域を設定し，信号値を測定した．各関心領域について，S0画像の信号値で正規化し比較した．【結果】中心部と左右辺縁部では，オフセット周波数が高くなるほど信号値は基準値に近づいた．上下辺縁部では，オフセット周波数補正なしの場合に周波数2 ppmで最も基準値との差が大きくなった．各オフセット周波数での全領域で，オフセット周波数補正ありの場合は補正なしと比較して，全て基準値に近づいた．【結論】我々が提案した解析手法は，CEST後処理の評価指標として系統誤差を特定するのに有用である．

金城佑奎, 金澤裕樹, 長澤良子, 谷口陽, 尾藤良孝, 小野順玄, 原田雅史, 千葉大輝, 松元友暉, 芳賀昭弘 :
Quantitative Parameter Mapping(QPM)を用いたミエリン描出能の検討: ポリエチレングリコールを用いたファントム実験,
第46回日本放射線技術学会秋季学術大会, 2018年10月.

(要約): 【目的】 quantitative parameter mapping(QPM)-MRIは，一度の撮像で定量値マップや任意のコントラスト画像を計算できる手法である．本研究は，myelinと分子量の近いポリエチレングリコール(PEG)と水の含有量の違いによる信号変化を定量するために，QPM-MRIを用いて検討した. 【方法】 3テスラMRI装置(日立社製)にて，3D-partially radio frequency-spoiled steady state gradient-echo法を用いてファントム実験を行った． PEG(平均分子量，420)と水の含有量が異なる水溶液(0-50 wt%)サンプルを配置したファントムを作成した．QPM-MRIの撮像条件は，TE，4.6-22.1 ms(∆TE，3.5 ms);TR，20，40 ms;フリップ角，10，25，35，40 deg.;RF phases，2，5，8，20，22とした．QPMデータセット撮像後，T1，T2*，PDの定量値マップを作成した．定量値画像の各サンプル内に関心領域を設定し，定量値を比較した．【結果】 PEG溶液(0，10，20，30，40，50 wt%)の測定した定量値は，T1，510 ± 25，342 ± 19，229 ± 13，152 ± 21，130 ± 17，118 ± 14 ms;T2*，338 ± 22，300 ± 22，275 ± 39，214 ± 36，179 ± 23，189 ± 28 ms;PD，218 ± 15，142 ± 6，99 ± 6，84 ± 10，71 ± 4，77 ± 12であった．PEG濃度が高くなるとT1，T2*，PDの減少する傾向を示した．【結論】分子量の近いmyelinでも同様の傾向を示すことが予想されるので，水含有量の変化がmyelinの信号変化に影響を及ぼす可能性があることを実験的に示すことができた．QPM-MRIは，加齢や疾患によるmyelin体積減少の評価に応用できる可能性がある．

後藤聡汰, 林裕晃, 冨田恵美, 上原匠, 紀本夏実, 金澤裕樹, 岡崎徹, 橋詰拓弥 :
角度依存性の少ない小型OSL線量計の開発に向けた一考察,
第46回日本放射線技術学会秋季学術大会, 2018年10月. 大友真姫, 阿部考志, 松元友暉, 金澤裕樹, 原田雅史 :
ASL法により観察された健常ボランティアにおける脳灌流の再現性と性差の評価,
第46回日本磁気共鳴学会大会, 2018年9月. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo, Amgalan Enkh Dolgorsuren, Ariumbold Gankhuyag, Takamatsu Shin and Yamashita Yuichi :
Determination of the thresholding values for virtual MR elastography,
JSMRM2018, Sep. 2018. Yuki Kanazawa, Yuki Kinjoh, Masafumi Harada, Hiroaki Hayashi, Yo Taniguchi, Yoshitaka Bito, Yuki Matsumoto and Masaharu Ono :
Construction of voxel-based morphometry of R1 and R2* derived from quantitative parameter mapping,
第46回日本磁気共鳴医学会大会, Sep. 2018.

(要約): The aim of our study is to construct of VBM using relaxation rate derived from QPM magnetic resonance imaging, i.e., novel Synthetic MRI. VBM of relaxation rates derived from QPM enable to made high quality and accuracy region matching for quantitative analysis of hemodynamic in brain.

Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo and Miyoshi Mitsuharu :
Chemical exchange saturation transfer imaging for brain tumors,
日本分子イメージング学会, Jun. 2018. 岡崎徹, 淺原孝, 橋詰拓弥, Cruz Vergil, Hsin Wei Cheng, 林裕晃, 冨田恵美, 後藤聡汰, 三原由樹, 金澤裕樹, 横山須美 :
小型OSL線量計を用いたIVR術者水晶体被ばく線量測定に向けた線量値の信頼性の検証,
日本保健物理学会第51回研究発表会, 2018年6月. TOMITA Emi, Hiroaki Hayashi, SHITAKUBO Yasufumi, SAKURAGAWA Kanako, Yuki Kanazawa, Hitoshi Ikushima, OKAZAKI Tohru, ASAHARA Takashi, HASHIZUME Takuya and MIYAHARA Yoshinori :
Rectum Dose Measurements Using Novel Dosimetric System During High-Dose-Rate 192Ir Brachytherapy Treatment of Cervical Cancer,
第74回日本放射線技術学会総会学術大会, Apr. 2018. Asahara Takashi, Hiroaki Hayashi, Tomita Emi, Goto Sota, Yokoyama Sumi, Yuki Kanazawa and Okazaki Tohru :
Proposal of Accurate Calibration for Measuring Eye Lens Dose of the Operator during Transfemoral Cardiac Catheterization with Fluoroscopic System Using an OSL dosimeter,
第74回日本放射線技術学会総会学術大会, Apr. 2018. Yuki Matsumoto, Masafumi Harada, Yuki Kanazawa, Maki Ohtomo, Ariunbold Gankhuyag, Amgalan Enkh Dolgorsuren and Hideki Otsuka :
Virtual MR elastography using IVIM stretched model,
Japanese Journal of Radiological Technology, Apr. 2018. 松元友暉, 原田雅史, 金澤裕樹, 大友真姫, ARIUNBOLD GANKHUYAG, DOLGORSUREN ENKH-AMGALAN, 大塚秀樹 :
Virtual-magnetic resonance elastography (MRE) using intravoxel incoherent motion (IVIM) stretched model,
第129回日本医学放射線学会中国・四国地方会, 2017年12月. 後藤聡汰, 林裕晃, 三原由樹, 淺原孝, 冨田恵美, 金澤裕樹, 岡崎徹, 橋詰拓弥, Vergil LE Cruz :
小型OSL線量計を用いた超精密測定に向けた固有効率の決定,
第45回日本放射線技術学会秋季学術大会, 2017年10月. 幸坂育歩, 金澤裕樹, 馬場幸太郎, 松元友暉, 林裕晃, 原田雅史 :
MR Elastographyの振動波定量解析,
第45回日本放射線技術学会秋季学術大会, 2017年10月. 馬場幸太郎, 金澤裕樹, 幸坂育歩, 松元友暉, 林裕晃, 原田雅史 :
lipid-rich-core プラークの物性に着目したマルチコンポーネント解析MRI,
第45回日本放射線技術学会秋季学術大会, 2017年10月. Yuki Matsumoto, Yuki Kanazawa, Masafumi Harada, Hiroaki Hayashi, Kotaro Baba, Mitsuharu Miyoshi and Hideki Otsuka :
Off-set frequency correction in brain for quantitative susceptibility mapping,
JSMRM2017, Sep. 2017. 松元友暉, 金澤裕樹, 原田雅史, 林裕晃, 馬場幸太郎, 幸坂育歩, 三好光晴, 大塚秀樹 :
定量的磁化率マッピング(QSM)のためのオフセット周波数補正法の提案,
Society of Advanced Medical Imaging (SAMI) 2017, 2017年7月. Takashi Asahara, Natsumi Kimoto, Hiroaki Hayashi, Yuki Kanazawa, Akitoshi Katsumata, Wataru Nishiyama, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki and Masahiro Okada :
Simulation study for effective reduction procedure of scattered Xrays toward high accuracy material identification based on photon counting technique,
第113回日本医学物理学会学術大会, Apr. 2017. Yoshiki Mihara, Kenji Yamada, Michihiro Yokoishi, Hiroaki Hayashi, Yuki Kanazawa, Tohru Okazaki and Takuya Hashizume :
First observation of dose exposure to assistants during pediatric X-ray procedure by means of a small-type OSL dosimeter,
第73回日本放射線技術学会総会学術大会, Apr. 2017. Yoshiki Mihara, Hiroaki Hayashi, Yuki Kanazawa, Kenji Yamada, Kazuki Takegami, Tohru Okazaki and Takuya Hashizume :
Visualization of entrance surface dose during CT examination using small-type OSL dosimeter,
第73回日本放射線技術学会総会学術大会, Apr. 2017. Yuki Matsumoto, Yuki Kanazawa, Toshiaki Sasaki, Hiroaki Hayashi, Natsuki Ikemitsu, Masafumi Harada and Hideki Otsuka :
Evaluation of Mechanical Waves of MR Elastography,
JSRT, Apr. 2017.

(要約): [Purpose] The purpose of our study is to assess the mechanical waves that occur during MR elastography using circular statistical analysis. [Methods] On a 1.5 T MR system, we performed a phantom experiment. The phantom was composed of two blocks of agar at a concentration of 0.75 and 1.0 wt%. All imaging data were acquired using gradient echo (GRE) specialized for MRE. The imaging parameters were TE, 19.4 ms; repetition time, 50 ms; field of view, 420 × 420 mm; slice thickness, 80 mm; bandwidth 32.3 kHz; motion-encoding gradient frequency, 60 Hz; driver amplitude, 70. After acquiring the dataset, MRE images were calculated from a multi scale direct inversion algorithm. Additionally, we measured mean wavelength values of offset phase images obtained during MRE using circular statistical analysis. [Results] Mean shear stiffness values at 0.75 wt% and 1.0 wt% agar concentrations were 1.95 ± 0.35 and 6.45 ± 0.97 kPa, respectively. Mean wavelength values for each agar concentration at three column line profile settings (from left to right side) were 1000 and 1920 mm for the 20th column, 760 and 1880 mm for the 90th column, and 160 and 1960 mm for the 160th column, respectively. [Conclusion] Circular statistical analysis makes it possible to obtain and evaluate more detailed information during MRE.

林裕晃, 三原由樹, 淺原孝, 紀本夏実, 金澤裕樹, 山田健二, 笠井亮佑, 岡崎徹, 橋詰拓弥, 小林育夫 :
小型OSL線量計を用いた小児X線撮影における介助者被ばく実測に向けた現状と課題,
医用画像情報学会(MII)平成28年度秋季(第176回)大会, 2016年10月. 松元友暉, 金澤裕樹, 池光捺貴, 佐々木俊晃, 臼田貴俊, 林裕晃, 三好光晴, 原田雅史, 大塚秀樹 :
How to make a phantom for quantitative susceptibility mapping.,
第44回日本放射線技術学会秋季学術大会, 2016年10月. 佐々木俊晃, 金澤裕樹, 松元友暉, 池光捺貴, 臼田貴俊, 林裕晃, 三好光晴, 原田雅史 :
MTパルスを付加したT1値の算出,
第44回日本放射線技術学会秋季学術大会, 2016年10月. 池光捺貴, 金澤裕樹, 松元友暉, 臼田貴俊, 林裕晃, 三好光晴, 原田雅史 :
T2* phase cycle SNR,
第44回日本放射線技術学会秋季学術大会, 2016年10月. 竹上和希, 三原由樹, 紀本夏実, 山田健二, 林裕晃, 金澤裕樹, 東野恒作, 岡崎徹, 橋詰拓弥 :
小型OSL線量計を用いたCTスキャンにおける入射皮膚線量実測の有用性,
第44回日本放射線技術学会秋季学術大会, 2016年10月. Kazuki Takegami, Yoshiki Mihara, Natsumi Kimoto, Hiroaki Hayashi, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Tohru Okazaki and Takuya Hashizume :
Study to expand the dose calibration curve of small-type OSL dosimeter toward scattered and penetrating X-rays for management of radiation exposure in the diagnostic region,
第44回日本放射線技術学会秋季学術大会, Oct. 2016. 沖野啓樹, 浅原孝, 三原由樹, 林裕晃, 金澤裕樹, 岡崎徹, 橋詰拓弥, 小林育夫 :
シミュレーションコードEGS5を用いた137Csと60Coのγ線に対する小型OSL線量計の角度依存性の評価,
第44回日本放射線技術学会秋季学術大会, 2016年10月.

(要約): 【目的】被ばく線量を測定する際，線量計の装着部位，光子の入射角は臨床条件によって変化するため，角度依存性を評価することは重要になる．本研究ではnanoDotの利用範囲を高エネルギー領域に拡張するために，137Csと60Coの線に対する角度依存性をモンテカルロシミュレーションで評価した．効率よく計算を行うために，電子平衡を考慮した独自の小さい照射体系を構築した．【方法】モンテカルロシミュレーションコード(EGS5)を用いた．小さい領域で電子平衡を達成させるために，nanoDotの周りに5 mmの厚みを有する球形のアクリルをビルドアップ物質として配置した照射体系を作成した．nanoDotの組成や構造はすでに報告されている論文のデータを参考にした．137Csと60Coの線をそれぞれnanoDotに対し0°∼360°の範囲で15°間隔で照射し，線量計に付与された総エネルギーを計算した．得られた角度依存性のデータは0°方向で規格化し，他の角度と比較評価した．照射野はアクリル球の直径(2.42 cm)に設定した．また統計誤差は1%未満になるように粒子数を4×109に設定した．【結果】角度依存性のデータは90°と270°方向を除いて0°方向とよく一致しており，この結果はすでに報告されている診断領域のデータと同様の傾向を示していた．90°と270°方向のデータに着目したとき，診断領域では0°方向と比較して値が30%低下したのに対し，137Csと60Co では約5%低下した値が得られた．【まとめ】被ばく線量測定において，線量計の角度依存性やエネルギー依存性は評価されなければならない．本研究では，137Csと60Coに対する被ばく線量測定においてnanoDotの角度依存性の影響は約5%の確度で保証されていることを示した．nanoDotは核医学や治療領域で臨床利用が期待できる線量計である．

三原由樹, 紀本夏実, 林裕晃, 金澤裕樹, 東野恒作, 竹上和希, 岡崎徹, 橋詰拓弥 :
診断用X線に対する小型OSL線量計の測定下限値の評価,
第44回日本放射線技術学会秋季学術大会, 2016年10月.

(要約): 【目的】小児のX線撮影においては，散乱X線によって介助者が被ばくをする．我々は，小型OSL線量計(nanoDot)を用いて低線量域の散乱X線による被ばくを測定することを計画している．本研究の目的は，線量測定システムの線量下限値を評価することである．【方法】実験は，診断用X線装置を用いて行った．まず，十分にアニーリングしたnanoDotを準備し，バックグラウンドを読み取った．次に，線量校正曲線を作成するために，自由空気条件および軟部組織等価ファントム上でnanoDotを照射し，対応する計数値と電離箱線量計の測定値を比べた．照射条件は，管電圧55, 83, 108 [kV]，管電流時間積0.5, 1, 2, 4, 7, 10, 20, 40, 100, 200 [mAs]，X線焦点-線量計距離150, 250 [cm]とした．各測定点での誤差評価を行い，線量校正曲線と矛盾がないかどうかを評価した．最後に，測定点での誤差が100%となる線量下限値を求めた．【結果】基準の校正曲線を83 [kV]の自由空気条件で取得し，異なる実験条件によって取得した実験データを矛盾なく説明できる系統誤差を評価したところ，±15%となることがわかった．線量計のバックグラウンドと計数値の統計誤差および系統誤差を用いて，誤差の伝播式から測定下限値を見積もったところ，5.0×10-4 [mGy]となった．【まとめ】我々は，小型OSL線量計の測定システムの線量下限値を評価するために，校正曲線を作成した．測定誤差が100%となるnanoDotの線量下限値を求めたところ，5.0×10-4 [mGy]となった．今後，小児X線撮影における介助者の散乱X線被ばくを実測する予定である．

Yoshiki Mihara, Kenji Yamada, Natsumi Kimoto, Hiroaki Hayashi, Yuki Kanazawa, Kousaku Higashino, Tohru Okazaki and Takuya Hashizume :
Basic study for internal dose evaluation of CT examination by means of small-type OSL dosimeter,
第44回日本放射線技術学会秋季学術大会, Oct. 2016.

(要約): 【目的】我々はCT検査の被曝線量の管理に向けて，小型OSL線量計を用いた基礎研究を行っている．入射皮膚表面ではPitch Factor (PF)ごとに線量分布にばらつきが生じるが，体内では散乱X線が発生することで，臓器に対する吸収線量はPFによる影響が少なくなることが想定される．本研究では，体内における吸収線量評価に着目して基礎実験を行った．【方法】東芝製の320列CT装置を使用し，アクリル板(計10枚)の中心部分に小型OSL線量計を埋め込めるように加工した自作の腹部ファントムを用いた実験を行った．線量計は体軸方向に10個並べ1セットとし，ファントム表面から1 cmごとに10 cmの深さまでのデータを取得した．照射条件は64列，管電圧120 kV, 管電流600 mA，PFは1.484とした．また，各照射方向からの寄与を評価するために，X線管を45度ごとに固定し，全ての線量計が照射される条件下での実験も行った．【結果】 PF1.484のヘリカルスキャンによる体軸方向の10個の線量の測定値のばらつきは，表面位置では20∼30%程度であり，中心(10 cm位置)に近づくにつれて数%まで減少した．この変動の原因は，OSL線量計に直接X線が照射されているかどうかの有無によって生じており，この揺らぎをOSL線量計で測定を行ったときの誤差と定義した．全ての線量計が照射されている条件下での0∼360度までの寄与を積分した値とヘリカルスキャンの実験結果との比較をおこない，上述の誤差に矛盾が無いことを確認した．【まとめ】小型OSL線量計を自作したファントムに埋め込み，CT検査における体内の吸収線量の誤差を評価するための基礎実験を行った．CT検査における吸収線量の変動は深部にいくにつれて散乱線の影響で均され，数%程度であることが明らかになった．今後，異なる条件化での実験を重ね，CT検査における体内の吸収線量評価に向けた知見を得たいと考えている．

Yuki Matsumoto, Yuki Kanazawa, Nattsuki Ikemitsu, Toshiaki Sasaki, Hiroaki Hayashi, Mitsuharu Miyosh, Masafumi Harada and Hideki Otsuka :
Noise estimation of phantom phase image in ultra-short echo time imaging,
JSMRM2016, Sep. 2016.

(要約): Purpose: To estimate accurately noise of phase rotation, we evaluated a signal phase of ultra-short echo time (UTE) imaging. Materials and Methods: On 3.0T MR system, we performed a phantom experiment using a dual-echo UTE imaging. The imaging parameters were TE, 0.032 ms (first-echo) and 3.3 ms (second-echo); matrix sizes, 256 ×256; slice, 16. The phantom consisted of Gd-DTPA and hydroxyapatite samples, which were made using three different concentrations of each material; Gd-DTPA, 0.5, 1.0, and 2.5 mmol/L; hydroxyapatite, 100, 200, and 350 mg/mL. Then, region of interest analysis was performed on two phase images, e.g., first-echo, and second-echo phase images. Results: The mean first-echo phase values on each Gd-DTPA (0.5, 1.0, and 2.5 mmol/L) and hydroxyapatite (100, 200, and 350 mg/mL) sample were 32.4 ± 0.04, 32.2 ± 0.04, 32.0 ±0.01, 32.4 ± 0.02, 43.6 ± 0.03, and 60.0 ± 0.01 degree, respectively. The mean second-echo phase values on each Gd-DTPA (0.5, 1.0, and 2.5 mmol/L) and hydroxyapatite (100, 200, and 350 mg/mL) sample were 39.1 ± 0.04, 36.0 ± 0.04, 35.5 ± 0.05, 137.9 ± 0.06, 83.4 ± 0.06, and 88.02 ± 0.06 degree, respectively. The mean background phase value first-echo, and second-echo were 33.5 ± 0.11 and 87.1 ± 0.12 degree, respectively. Discussion & Conclusion: The phase rotation of hydroxyapatite occurred difference of phase value in each sample, i.e., this leads good contrast in UTE image. In contrast, the phase rotation of Gd-DTPA at TE 0.032 ms is small enough to estimate noise because the Gd-DTPA phase values were almost equal. Thus, UTE imaging may lead to noise derived from a phase rotation. Noise estimation using UTE imaging may render it possible to obtain more detailed information of paramagnetic materials, e.g., Gd-DTPA.

三原由樹, 紀本夏実, 沖野啓樹, 林裕晃, 金澤裕樹, 東野恒作, 竹上和希, 岡崎徹, 橋詰拓弥 :
診断領域X線による介助者被ばくの実測に向けた小型OSL線量計の読取装置の改良,
医用画像情報学会平成28年度年次(第175回)大会, 2016年6月. 小畠巧也, 金澤裕樹, 小川和郎, 大塚秀樹 :
三次元高速スピンエコー法を用いたMR angiographyにおける血液信号シミュレーション,
第72回日本放射線技術学会総会学術大会, 2016年4月. Yuki Matsumoto, Yuki Kanazawa, Usuda Takatoshi, Hiroaki Hayashi, Matsuda Tsuyoshi, Masafumi Harada and Hideki Otsuka :
Dependence on echo time for quantitative susceptibility mapping (QSM) MRI.,
JSRT, Apr. 2016. Usuda Takatoshi, Yuki Kanazawa, Yuki Matsumoto, Hiroaki Hayashi, Masafumi Harada, Hideki Otsuka and Matsuda Tsuyoshi :
Normalization of time-dependent signal change of MRI,
JSRT, Apr. 2016. Natsumi Kimoto, Hiroki Okino, Kazuki Takegami, Hiroaki Hayashi, Yuki Kanazawa, Tsutomu Yamakawa and Shuichiro Yamamoto :
Proposal of a New Analytic Method for the Determination of Both Atomic Number and Sample Thickness Based on a Photon Counting Technique Using Diagnostic X-rays,
第72回日本放射線技術学会学術大会_Next Generation Session(学生選抜セッション), Apr. 2016.

(要約): [Purpose] Currently researchers are focusing attention on a photon counting system to be used for next generation X-ray diagnosis. Although there are many research articles concerning the development of a detector, few studies have been published about analytic methodologies. Currently, X-ray procedures are widely applied to medical examinations; therefore a proposal of a new technique has a spillover effect on the development of diagnosis. In this study, we proposed a new analytic method in which both the effective atomic number and thickness of the sample can be derived. [Methods] X-ray spectra are measured after penetrating the substances. Then, concerned the different energies (E1, E2), μ1t and μ2t were numerically determined and the ``normalized liner attenuation factor'' was calculated by means of μ1t and μ2t. Here, to derive effective atomic number of the sample, we proposed a calibration curve between normalized linear attenuation factor and atomic number Z based on a well-known database. Moreover, to derive the thickness of the sample another calibration curve determined Z and mass attenuation factor was derived. Using the determined mass attenuation factor, thickness of the substance can be analyzed. Experiments were carried out in which X-ray spectra after penetrating soft-tissue-equivalent phantoms (Kyoto kagaku, XUR) having thicknesses of 20-160 mm and bone-equivalent phantoms (Kyoto kagaku, BE-H) having thicknesses of 4.1-41.5 mm were measured with a CdTe detector (EMF Japan, EMF123). The thicknesses of these phantoms were optimized so as to obtain equal-image densities when a traditional X-ray diagnosis system was used to take the X-ray image. [Results] Our method can differentiate two-types of phantoms. The determined atomic numbers were consistent with theoretical values of 11.7 (bone) and 7.0 (soft-tissue). In addition, the derived thicknesses were also in good agreement with the real thicknesses in the dimension of ρt [g/cm2]. [Conclusion] We proposed a new analytic method to derive effective atomic number and thickness of the sample.

沖野啓樹, 竹上和希, 紀本夏実, 林裕晃, 金澤裕樹, 岡崎徹, 橋詰拓弥 :
小型OSL線量計を用いた137Csと90Srの分離測定に関する基礎的研究,
第72回日本放射線技術学会学術大会, 2016年4月.

(要約): [目的] 福島原発で飛散した放射性核種において，長期間にわたり線量測定の対象となるものには物理学的半減期の長い137Csと90Srが考えられる．137Csはγ線を放出するため，Ge半導体検出器により放射能を測定することができる．90Srは90Yと永続平衡状態で存在するβ線放出核種で，主に液体シンチレータなどで測定される．137Csと90Srが混合する放射線場において一般の線量計を用いて簡易的に放射能を分離測定することができれば，安全管理に役立つ．今回我々は，厚みの薄い小型OSL線量計(nanoDot)に着目し，137Csと90Srが混合する線源を想定して，それぞれの核種の放射能を推定するための基礎検討を行った． [方法] モンテカルロシミュレーションコードEGS5を用いて，nanoDotと1 mmの鉛フィルターで覆ったnanoDotを作成した．137Csと90Srから放出されるγ線とフェルミ関数を用いた理論式より計算したβ線スペクトルを順次nanoDotに照射し，応答関数を計算した．また，137Csのγ線放出と競合過程にある内部転換電子の応答関数も計算した．nanoDotに付与される線量は放射能と応答関数の積の総和である．フィルターありとなしで得られた線量に対し，137Csと90Srのそれぞれの放射能を未知数とした連立方程式を定義した．最後に，137Csと90Srを適当な割合で混合させた4π線源を作成し，nanoDotに照射し，連立方程式を用いて放射能を分離測定できるかを検討した． [結果および考察] 前述の連立方程式を解くことで，nanoDotを用いて137Csと90Srが混合する線源からそれぞれの核種の放射能を算出することができた．nanoDotと鉛フィルターを併用することで，β線放出核種とγ線放出核種が混合する放射線場においても各々の放射能を推定できる可能性が示唆された．

Kazuki Takegami, Hiroki Okino, Natsumi Kimoto, Hiroaki Hayashi, Yuki Kanazawa, Tohru Okazaki and Takuya Hashizume :
Phantom Study for Entrance-Skin Doses Measurement in the Diagnostic X-ray Region using a Small-type OSL dosimeter Comparison of the doses measured with other detectors-,
第72回日本放射線技術学会学術大会, Apr. 2016.

(要約): [Aims] Recently, a small-type optically stimulated luminescence(OSL) dosimeter, named nanoDot, was developed by Landauer Inc. It is expected to be a convenient detector to measure the entrance-skin dose(ESD) because this dosimeter does not interfere with the medical image. Up to now, we have reported on a calibration curve for the ESD measurement and image evaluation. From our previous research, it was clarified that the nanoDot OSL dosimeter can directly measure the ESD based on the calibration curve without considering BSF. For the clinical application of the nanoDot OSL dosimeter, it is important to verify the adequacy of our measurement method. In this presentation, we compared and evaluated the ESD measured with the nanoDot OSL dosimeter to that of other detectors. [Materials and Methods] X-rays were generated by diagnostic X-ray equipment. We used a soft-tissue equivalent phantom instead of a human body, and the nanoDot OSL dosimeter was placed in front of the phantom. X-rays were irradiated under general clinical conditions and a measured count was derived using a reading device. The count was converted to the ESD using our calibration curve. In the measurements using an ionization chamber and a thermo-luminescence dosimeter(TLD), we used standard methodologies. Additionally, the guidance level suggested in the IAEA was used as a reference. [Results and conclusion] In the present study, the ESDs for various places on the human bodies were measured. For example, for the chest radiography, the ESD measured with the nanoDot OSL dosimeter was 0.24 [mGy]. Here, the guidance level found in the IAEA is 0.4 [mGy], and the ESDs measured with the ionization chamber and TLD were 0.26 and 0.27 [mGy], respectively. Our results were consistent with those of other detectors. In conclusion, it was found that the nanoDot OSL dosimeter is a convenient detector to measure the ESD without interfering with medical image.

沖野啓樹, 竹上和希, 紀本夏実, 林裕晃, 金澤裕樹, 岡崎徹, 橋詰拓弥 :
EGS5を用いた核医学検査領域における小型OSL線量計の検出効率の評価,
第72回日本放射線技術学会学術大会, 2016年4月.

(要約): [目的] 近年，小型OSL線量計(nanoDot) (1cm(縦)×1cm(横)×0.2cm(厚さ))を用いた被ばく線量の実測に向けた研究が盛んにおこなわれている．我々は診断領域におけるnanoDot線量計の角度依存性およびエネルギー依存性を評価し，本学会で報告してきた．一方で，核医学検査領域などの高エネルギー光子線を対象にした場合，発生する二次電子の飛程が長くなるため，二次電子平衡を考慮しなければならない．我々は前年の秋季学術大会において，電子平衡を成立させるための効率的な照射体系を提案した．本研究では提案体系をnanoDotに適用し，100-1500 keVにおけるnanoDotの検出効率のエネルギー依存性を評価した． [方法] モンテカルロシミュレーションコードEGS5を用いて，nanoDotの全面をファントムで覆う体系を作成した．ファントム厚と照射野の大きさはファントム中で発生する二次電子の最大飛程を含むように決定した．照射粒子には100-1500 keVの単色光子を用いた．nanoDotに入射する光子フルエンスと空気の質量吸収係数から入射空気カーマ(Kcol)を算出し，吸収線量(D)との比(D/Kcol)を検出効率とした．また提案体系の有用性を示すために，nanoDotのみで構成される照射体系でのシミュレーションを行い，提案体系と同様の解析を行った． [結果および考察] 提案体系を用いた場合，200-1500 keVの範囲でD/Kcol は一定の値を示した．一方で，nanoDotのみを配置した場合，100-400 keVの範囲で提案体系と矛盾無い結果が得られたが，500 keV以上でD/Kcolが系統的に低下した．この結果は，提案体系が二次電子平衡を考慮した有効な検出効率の評価手法であることを示している．

紀本夏実, 沖野啓樹, 竹上和希, 林裕晃, 金澤裕樹 :
初学者の電離作用の理解に向けた箔検電器の開発,
第72回日本放射線技術学会学術大会, 2016年4月.

(要約): [目的] 放射線と物質との相互作用を理解することは初学者にとって重要である．診療放射線技師の養成校で使用される教科書では放射線の電離作用について冒頭に述べられているが，光電効果やコンプトン散乱などの知識を習得していない初学者にとってこの現象を理解することは難しい．本研究の目的はX線の電離作用を可視化する箔検電器を製作し，X線の物理的特性の理解に向けた初学者実習を提案することである． [方法] 製作した箔検電器はX線の照射部分とその電離作用を検出できる箔の存在する部分で構成されている．これらの空間は自作のアクリルおよび金属メッシュのセパレータで仕切ることができる．さらに真空ポンプを用いて真空状態を生成する機能を付加した．あらかじめ箔検電器に正電荷を帯電させ，箔の開いた状態を生成した．X線の照射を行い，これらの付加機能を用いて電離作用を確認した． [結果および考察] セパレータを設置しないとき箔は閉じた．これはX線を照射することによって生じた電子が箔の電荷に結合する物理的現象を示している．アクリルおよび金属メッシュのセパレータを設置したとき箔は開いた状態を保った．アクリルのセパレータは電離空間と箔の存在する空間を隔てる働きをしており，金属メッシュのセパレータは箔の電場を遮断する働きをしていることを示している．さらに真空ポンプを使用したとき，箔は開いた状態を維持した．これは真空状態では電子の生成が不十分であることを示している． [結論] セパレータと真空状態を生成する機能を有する箔検電器を製作した．この装置により簡便にX線の電離作用を理解することができ，初学者に対して教育効果を発揮することが期待できる．

Natsumi Kimoto, Hiroki Okino, Kazuki Takegami, Hiroaki Hayashi, Yuki Kanazawa, Tsutomu Yamakawa and Yamamoto Shuichiro :
Fabrication of the equal-image-density materials for basic experiment of next-generation-type X-ray diagnosis system,
第72回日本放射線技術学会学術大会, Apr. 2016.

(要約): [Purpose] X-ray equipment is widely used for diagnosis in the medical field. Using a CR (computed radiography) system, signal (contrast) of the image is determined by the products of the energy and quantity of X-rays. Therefore, when the products of linear attenuation coefficient and thickness are similar among the materials, we cannot differentiate the different materials. Identification will be essential for X-ray diagnosis in the near future. Recently, a photon counting system with energy resolving capability is attracting attention in the medical field. At present, the system has been progressing, but currently a fundamental study is needed. The aim of this study is to fabricate ``equal-image-density materials'' which give the same digital value, and to analyze the materials in terms of the influence on the contamination rate from scattered X-ray and heel effect on the obtained image. [Methods] Using machine tools, we ground down commercially available materials, bone-equivalent, soft-tissue-equivalent, aluminum and acrylic, so as to obtain the equal-image-density. Our materials were cubic shapes having 4 cm square and different thickness of 0.2-18 cm. Then, the influences of the scattered X-rays and the heel effect were evaluated experimentally. The contamination rate from scattered X-rays was determined by the collimator method. The heel effect on the obtained digital value was measured by an experiment in which the X-ray equipment was tilted at a 5 degree angle. [Results] For 40 kV and 100 kV X-rays, equal-image-density materials were fabricated. We found that the contamination rates from scattered X-ray were 8-60% for 40 kV X-rays and 10-53% for 100 kV X-rays. For the heel effect the intensity differences were 1-15% for 40 kV X-rays and 0.1-9% for 100 kV X-rays. [Conclusion] We fabricated equal-image-density materials, and then, using the materials, we analyzed the influences of the contamination rate and the heel effect. They are considered to be valuable for fundamental studies for next-generation detection systems such as a photon counting system.

Kazuki Takegami, Hiroki Okino, Natsumi Kimoto, Hiroaki Hayashi, Yuki Kanazawa, Tohru Okazaki and Ikuo Kobayashi :
Practical calibration curve for entrance-skin dose measurement using small-type OSL dosimeter,
第72回日本放射線技術学会学術大会, Apr. 2016.

(要約): Aims It is becoming increasingly important to manage the exposure dose for patients in the diagnostic X-ray region. Generally, the dose is estimated by an ionization chamber based on an air-kerma measurement. The dosimeter cannot be applied to actual clinical settings because they interfere with the medical image. Recently, a small-type optically stimulated luminescence(OSL) dosimeter, called nanoDot, was newly developed by Landauer, Inc. Because the OSL dosimeter does not interfere with the medical image in the diagnostic X-ray region, the dosimeter is hoped to be a convenient detector used for the measurement of patient exposure dose. In this study, we proposed the measurement method using a small-type OSL dosimeter for clinical application used to measure patient dose. Materials and Methods First, based on the generally adopted method using an ionization chamber, the air-kerma was measured in free-air condition, and then the entrance-skin dose(ESD) was estimated by correction of the back-scatter factor(BSF). Second, measured values of the OSL dosimeter were derived in the same experimental conditions. Then, a calibration curve, which has a relationship between the measured value and the ESD, was derived. Third, we clarified the uncertainty of the calibration curve considering the angularity, energy dependences, etc. Finally, we measured the ESD based on a general clinical setting, and the derived ESD was compared to those measured with other dosimeters and guidance level of IAEA. Results and conclusion The calibration curve shows good linearity. It was found that the accuracy of the curve was 15%. The accuracy was consistent with the error cause discussed above. The ESD derived by our calibration curve was consistent with the other reference values. Based on the present study, the OSL dosimeter is further expected to be a useful dosimeter for measuring the ESD of the patients without affecting the medical image.

岡崎徹, 橋詰拓弥, 林裕晃, 竹上和希, 沖野啓樹, 紀本夏実, 前畑伊採, 金澤裕樹, 小林育夫 :
nanoDot OSL線量計の診断用X線領域におけるエネルギー依存性,
日本放射線安全管理学会第14回学術大会, 2015年12月. 橋詰拓弥, 岡崎徹, 竹上和希, 林裕晃, 沖野啓樹, 紀本夏実, 前畑伊採, 金澤裕樹, 小林育夫 :
OSL線量計の診断領域X線に対する基礎実験∼線量計着用における医用画像への影響評価∼,
日本放射線安全管理学会第14回学術大会, 2015年12月. 臼田貴俊, 金澤裕樹, 小西優斗, 松元友暉, 林裕晃, 原田雅史, 松田豪 :
MR信号の線形評価を目的とした正規化手法の比較,
第43回日本放射線技術学会秋季学術大会, 2015年10月. 紀本夏実, 前畑伊採, 竹上和希, 沖野啓樹, Hiroaki Hayashi, Yuki Kanazawa and 山河勉 :
Two dimensional material identification method based on a photon counting technique using low-energy X-ray spectrum,
第43回日本放射線技術学会秋季学術大会, Oct. 2015. 小西優斗, 金澤裕樹, 臼田貴俊, 松元友暉, 林裕晃, 原田雅史, 松田豪 :
拡散強調画像の統計学的信号補正の比較,
第43回日本放射線技術学会秋季学術大会, 2015年10月. 前畑伊採, Hiroaki Hayashi, 紀本夏実, 竹上和希, 沖野啓樹 and Yuki Kanazawa :
High accuracy measurement of contamination rate of scattered X-ray in air-kerma to construct secondary standard using diagnostic X-ray apparatus,
第43回日本放射線技術学会秋季学術大会, Oct. 2015. 竹上和希, 沖野啓樹, 紀本夏実, 前畑伊採, Hiroaki Hayashi, Yuki Kanazawa, 岡崎徹, 橋詰拓弥 and 小林育夫 :
Basic research for clinical application of the OSL dosimeter in the diagnostic region -Estimation of irradiation conditions not to identify the dosimeter on the medical image-,
第43回日本放射線技術学会秋季学術大会, Oct. 2015. 竹上和希, 沖野啓樹, 紀本夏実, 前畑伊採, Hiroaki Hayashi, Yuki Kanazawa, 岡崎徹, 橋詰拓弥 and 小林育夫 :
Measurement of energy dependence for small type OSL dosimeter by means of diagnostic X-ray equipment,
第43回日本放射線技術学会秋季学術大会, Oct. 2015. 竹上和希, 沖野啓樹, 紀本夏実, 前畑伊採, 林裕晃, 金澤裕樹 :
CRシステムを用いた診断領域の散乱X線可視化装置の開発,
第43回日本放射線技術学会秋季学術大会, 2015年10月. 沖野啓樹, 竹上和希, 紀本夏実, 前畑伊採, Hiroaki Hayashi, Yuki Kanazawa, 岡崎徹, 橋詰拓弥 and 小林育夫 :
Basic study for calculation of exposure dose of small type OSL dosimeter for high energy photon beam by means of simulation code(EGS5),
第43回日本放射線技術学会秋季学術大会, Oct. 2015. 林裕晃, 金澤裕樹, 竹上和希, 沖野啓樹, 紀本夏実, 前畑伊採 :
自作箔検電器を用いた初学者の物理教育-電離作用の理解に向けて-,
第43回放射線技術学会秋季学術大会, 2015年10月. 岸田弥奈, 原田雅史, 金澤裕樹, 船越康宏, 松田豪 :
3D-ASL法による脳血管流速測定値に対する通過時間補正の検討:加齢による影響について,
第46回日本磁気共鳴医学会大会, 2015年9月. 金澤裕樹, 臼田貴俊, 山田哲哉, 木戸晶, 藤本晃司, 高倉京子, 小澤聡, 小泉幸司, 大國万希子, 植田直見, 富樫かおり :
水浸出土木材の含浸物質濃度と緩和時間変化,
第43回日本磁気共鳴医学会大会, Vol.35, No.S, 412, 2015年9月. 金澤裕樹, 小西優斗, 臼田貴俊, 松元友暉, 林裕晃, 原田雅史, 松田豪 :
ライス分布を用いた拡散強調画像の信号補正,
第43回日本磁気共鳴医学会大会, 2015年9月. 沖野啓樹, 竹上和希, 紀本夏実, 前畑伊採, 林裕晃, 金澤裕樹, 岡崎徹, 橋詰拓弥, 小林育夫 :
100-2000keVの光子線に対する小型OSL線量計の効率的な照射体系の提案,
第22回EGS研究会, 2015年8月. 紀本夏実, 前畑伊採, 竹上和希, 沖野啓樹, 林裕晃, 金澤裕樹, 山河勉, 山本修一郎, 山崎雅志, 岡田雅宏 :
低エネルギーX線スペクトルのフォトンカウンティングに基づく2次元的物質同定法の提案,
医用画像情報学会第172回大会, 2015年6月. Kishida Mina, Hunakoshi Yasuhiro, Yuki Kanazawa, Matsuda Tsuyoshi and Masafumi Harada :
Influence of the Transit Time Correction for on Quantitative Cerebral Blood Flow (CBF) Values of Young and Elderly Subjects Using the 3D-ASL Method with Different Labeling Durations,
The 71 th Annual Scientific Congress of JSRT, Apr. 2015. 金澤裕樹, 山田哲也, 木戸晶, 藤本晃司, 小澤聡, 小泉幸司, 大國万希子, 植田直見, 富樫かおり :
磁化移動効果を用いたポリエチレングリコールの浸透性測定,
第42回日本磁気共鳴医学会大会, 2014年9月. 金澤裕樹, 山田哲也, 木戸晶, 藤本晃司, 小澤聡, 小泉幸司, 大國万希子, 植田直見, 富樫かおり :
MRIを用いた水浸出土木材の内部性状の可視化 ―磁化移動効果を用いたポリエチレングリコールの浸透性測定―,
日本文化財科学会第31大会, 2014年7月. 金澤裕樹, 伏見育崇, 藤本晃司, 木戸晶, 岡田知久, 高倉京子, 坂下尚孝, 富樫かおり :
CEST 効果におけるSaturation パルスの影響,
第41回日本磁気共鳴医学会大会, 2013年9月. Taha Mehemed, 伏見育崇, 岡田知久, 山本憲, 金柿光憲, 森本笑子, 坂本亮, 中島諭, 山田浩史, 柿木崇秀, 坂田昭彦, 百々俊樹, 奥知左智, 高倉京子, 金澤裕樹, 木戸晶, 藤本晃司, 坂下尚孝, 富樫かおり :
テスラ MRI における酸素吸入下での脳脊髄液の経時的な信号変化,
第41回日本磁気共鳴医学会大会, 2013年9月. 高倉京子, 藤本晃司, 木戸晶, 伏見育崇, 梅岡成章, 岡田知久, 坂下尚孝, 木村徳典, 金澤裕樹, 富樫かおり :
3D-SSFP-ASL(ASTAR)を用いた腎血流量計測,
第41回日本磁気共鳴医学会大会, 2013年9月. 高倉京子, 藤本晃司, 木戸晶, 伏見育崇, 梅岡成章, 岡田知久, 坂下尚孝, 木村徳典, 金澤裕樹, 富樫かおり :
プロトン密度強調(PDw)画像を用いない腎血流量定量の試み,
第41回日本磁気共鳴医学会大会, 2013年9月. 金澤裕樹, 八木絢子, 中島清貴, 加藤良美, 平川益三, 佐藤修 :
頭蓋内腫瘍診断における造影T1強調3D-FSPGR-SPAIR法の最適化,
第40回日本磁気共鳴医学会大会, 2012年9月. 八木絢子, 金澤裕樹, 中島清貴, 加藤良美, 平川益三 :
頭部領域における 3 次元fast spoiled gradient-echo (3D-FSPGR) 法を用いた造影脂肪抑制 T₁ 強調 MRI の最適化,
第68回日本放射線技術学会総会学術大会, 2012年4月. 金澤裕樹, 宮地利明, 佐藤修 :
膀胱癌のADCとDCE - MRIパラメ-タの比較,
第39回日本磁気共鳴医学会大会, 2011年10月. 金澤裕樹, 宮地利明, 八木絢子, 吉田彩, 田口賢治 :
T₁計測Look-Lockerシーケンスの最適化,
第67回日本放射線技術学会総会学術大会, 2011年4月. Yuki Kanazawa, 宮地利明, 佐藤修 and 田添潤 :
Plaque characteristics in carotid artery using three-dimensional Look-Locker sequence,
第38回日本磁気共鳴医学会大会, Oct. 2010. 金澤裕樹, 宮地利明, 八木絢子, 吉田彩, 田口賢治 :
高速スピンエコー法を用いた組織 T₁・T₂同時計測MRI,
第66回日本放射線技術学会総会学術大会, 2010年4月. 金澤裕樹, 宮地利明, 佐藤修 :
組織血流動態定量解析: T₁ Dynamic Contrast -Enhanced Fast Spin-Echo (T1DCE-FSE) MRIのモデルフィッティングに関する考察,
第37回日本磁気共鳴医学会大会, 2009年10月. 金澤裕樹, 宮地利明, 八木絢子, 吉田彩, 加藤良美, 佐藤修 :
動脈における低角再収束パルス高速スピンエコー法を用いた血流抑制血管壁MRI,
第65回日本放射線技術学会総会学術大会, 2009年4月. 金澤裕樹, 宮地利明, 八木絢子, 吉田彩, 井上雄介 :
高速スピンエコー法を用いたT₁値計測のT₂補正,
第51回日本放射線技術学会近畿部会学術大会, 2008年2月. 金澤裕樹, 宮地利明, 井上雄介 :
高速スピンエコー法による前立腺ダイナミック T₁値計測MRIの試み,
第63回日本放射線技術学会総会学術大会, 2007年4月. 金澤裕樹, 宮地利明, 井上雄介, 李哲柱, 岡部春海 :
Fast Recovery Fast spin echo (FR-FSE) 法を用いた脂肪抑制T₂ 強調画像の検討,
第16回日本乳癌画像研究会, 2007年2月. 金澤裕樹, 宮地利明, 井上雄介 :
高速spin-echo法を用いた組織T₁値計測に関する検討,
第50回日本放射線技術学会近畿部会学術大会, 2007年1月.

研究会・報告書

Hiroaki Hayashi, N. Kimoto, I. Maehata, K. Takegami, H. Okino, Yuki Kanazawa, M. Okada, T. Yamakawa, S. Yamamoto and M. Yamasaki :
A Fundamental Experiment for Novel Material Identification Method Based on a Photon Counting Technique: Using Conventional X-Ray Equipment,
IEEE Nuclear Science Symposium & Medical Imaging Conference, Conference Record, 2015.

(出版サイトへのリンク): ● Publication site (DOI): 10.1109/NSSMIC.2015.7582027
(文献検索サイトへのリンク): ● Summary page in Scopus @ Elsevier: 2-s2.0-84994106012

(DOI: 10.1109/NSSMIC.2015.7582027, Elsevier: Scopus) H. Okino, Hiroaki Hayashi, K. Takegami, N. Kimoto, I. Maehata, Yuki Kanazawa, T. Okazaki, T. Hasizume and I. Kobayashi :
Proposal of efficient irradiation system of small type OSL dosimeter for photon beams between 100-2000 keV,
KEK proceedings, Vol.2015-6, 1-10, Tsukuba, 2015. 金澤裕樹 :
平成20年度後期国際研究集会派遣会員報告書,
日本放射線技術学会雑誌, Vol.65, No.12, 1692-1701, 2009年12月.

特許: Yo Taniguchi, Yuki Kanazawa and Masaharu Ono : IMAGE PROCESSING APPARATUS, MAGNETIC RESONANCE IMAGING APPARATUS INCLUDING THE SAME, AND MAGNETIC RESONANCE IMAGING SYSTEM, (Nov. 2019), P16/675482. 谷口陽, 金澤裕樹, 小野順玄 : 画像処理装置，及び，それを含む磁気共鳴イメージング装置及び磁気共鳴イメージングシステム, (2018年11月), 特許第P2018-208813号.
作品: 研究者総覧に該当データはありませんでした。
補助金・競争的資金: 光子計数型X線撮影による被写体の定量分析技術の開発と骨強度の定量指標の導出 (研究課題/領域番号: 24K03306 )
臨床実現を目指した脳組織水フラクショナルMRイメージングの確立 (研究課題/領域番号: 23K07135 )
軟部腫瘍のアミノ酸代謝解析とアミドプロトン解析に着目したマルチ分子イメージング (研究課題/領域番号: 22K07696 )
脱髄性疾患に対する統合的定量ミエリンイメージングの開発 (研究課題/領域番号: 20K07997 )
放射線治療時のリスク臓器線量のインビボ測定に向けたディスポーザブル線量計の開発 (研究課題/領域番号: 19K08223 )
アテローム硬化症に伴う血管壁プラークの物性と生体変化の融合評価法の開発 (研究課題/領域番号: 17K09065 )
ＭＲＩを用いた水浸出土木材の内部性状の可視化に関する基礎的研究 (研究課題/領域番号: 24501264 )
研究者番号（80714013）による検索

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2024年12月20日更新

専門分野・研究分野: 放射線科学
医用イメージング (Medical Imaging)
所属学会・所属協会: 社団法人日本放射線技術学会
日本磁気共鳴医学会
International Society for Magnetic Resonance in Medicine
Radiological Society of North America
日本放射線技術学会中四国支部MR研究会
委員歴・役員歴: International Society for Magnetic Resonance in Medicine (ISMRM)
受賞: 2008年4月, 研究奨励賞( MR 部門) (社団法人日本放射線技術学会)
2015年11月, 第43回日本放射線技術学会秋季学術大会座長推薦優秀発表賞 (社団法人日本放射線技術学会)
2016年3月, 徳島大学大学院医歯薬学研究部長表彰 (徳島大学)
2016年3月, ISMRM Travel Award (一般社団法人日本磁気共鳴医学会)
2016年4月, 第72回日本放射線技術学会 Next Generation Session 最優秀学生賞 (社団法人日本放射線技術学会)
2016年4月, 第72回日本放射線技術学会総会学術大会座長推薦優秀発表賞 (社団法人日本放射線技術学会)
2016年10月, 第44回日本放射線技術学会秋季学術大会座長推薦優秀研究発表 (社団法人日本放射線技術学会)
2016年11月, CIRMS Ribbon Award (Council on ionizing radiation measurements and standards)
2016年11月, Certificate of merit (Radiological Society of North America)
2017年4月, RPT journal Doi paper award (社団法人日本放射線技術学会)
2017年6月, 第73回日本放射線技術学会総会学術大会座長推薦優秀研究発表 (社団法人日本放射線技術学会)
2017年12月, 第45回日本放射線技術学会秋季学術大会座長推薦優秀研究発表 (社団法人日本放射線技術学会)
2018年3月, 'Invest in the Youth'programme (European Congress of Radiology)
2018年4月, RPT most citiation award (社団法人日本放射線技術学会)
2018年4月, 第74回日本放射線技術学会総会学術大会, CyPos賞(SilverMedal) (社団法人日本放射線技術学会)
2018年4月, 第74回日本放射線技術学会総会学術大会, 学生賞 (社団法人日本放射線技術学会)
2018年4月, 第74回日本放射線技術学会総会学術大会座長推薦優秀研究発表 (社団法人日本放射線技術学会)
2018年6月, 第45回日本放射線技術学会秋季学術大会いいね賞(2位) (社団法人日本放射線技術学会)
2018年6月, 第45回日本放射線技術学会秋季学術大会いいね賞(6位) (社団法人日本放射線技術学会)
2018年6月, 第45回日本放射線技術学会秋季学術大会座長推薦優秀研究発表 (社団法人日本放射線技術学会)
2018年9月, 第46回日本磁気共鳴医学会大会座長推薦優秀研究発表 (第46回日本磁気共鳴医学会大会)
2018年11月, 第46回日本放射線技術学会秋季学術大会，座長推薦優秀発表賞 (社団法人日本放射線技術学会)
2018年12月, 第46回日本放射線技術学会秋季学術大会座長推薦優秀研究発表 (社団法人日本放射線技術学会)
2018年12月, 優秀ポスター賞 (ISMRM Japanese Chapter)
2019年3月, Certificate of Merit Award (ECR 2019 Scientific Exhibition)
2019年4月, 第75回日本放射線技術学会総会学術大会, 座長推薦優秀発表賞 (社団法人日本放射線技術学会)
2019年6月, 第75回日本放射線技術学会総会学術大会のCyPos''いいね投票''(10位) (社団法人日本放射線技術学会)
2019年12月, Certificate of Merit Award, RSNA2019 Education Exhibit Presentation (RSNA)
2020年5月, 第76回日本放射線技術学会総会学術大会座長推薦優秀研究発表 (社団法人日本放射線技術学会)
2022年12月, 座長推薦発表 (社団法人日本放射線技術学会)
2023年6月, 第79回日本放射線技術学会総会学術大会座長推薦者発表 (社団法人日本放射線技術学会)
2023年12月, 第51回日本放射線技術学会秋季学術大会座長推薦者発表 (社団法人日本放射線技術学会)
2024年2月, ECR2024, European Congress of Radiology Scientific Exhibition Jury, Certificate of Merit Award
2024年3月, 医学部優秀教育賞(保健学優秀教育賞) (徳島大学)
活動: 3年クラス副担任 (2016年4月〜2021年)

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2024年12月14日更新

研究者番号: 80714013

所属（現在）: 2024/4/1 : 徳島大学, 大学院医歯薬学研究部(医学域), 助教

所属（過去の研究課題 情報に基づく）*注記: 2018/4/1 – 2024/4/1 : 徳島大学, 大学院医歯薬学研究部(医学域), 助教
2017/4/1 : 徳島大学, 大学院医歯薬学研究部(医学系), 助教
2014/4/1 : 徳島大学, 大学院医歯薬学研究部(医学系), 助教

審査区分/研究分野

研究代表者

生物系 / 医歯薬学 / 境界医学 / 医学物理学・放射線技術学
小区分52040:放射線科学関連

研究代表者以外

総合・新領域系 / 総合領域 / 文化財科学 / 文化財科学
小区分52040:放射線科学関連
小区分90130:医用システム関連
小区分90140:医療技術評価学関連
合同審査対象区分:小区分90130:医用システム関連、小区分90140:医療技術評価学関連

キーワード

研究代表者

磁気共鳴画像（MRI） / アテローム性動脈硬化 / 脂質異常 / 緩和時間 / 化学交換 / 物性 / 分子イメージング / Atherosclerotic Plaque / UTE / CEST / MRI / CEST効果 / APT / 定量評価 / MT効果 / NOE / B1 / B0 / タンパク質 / 脂質 / 石灰化 / UTEイメージング / 緩和時間計測 / 解析・評価 / 核磁気共鳴画像 / 循環器・高血圧 / 物理学 / 髄鞘（ミエリン） / 磁化率 / 拡散係数 / 磁化移動 / 機械学習 / ミエリン / MWF / MT / DKI / VBM / SVM / 脳神経 / 組織分画水容積分布

研究代表者以外

水浸出土木材 / MRI / MR画像 / 保存処理 / ポリエチレングリコール / トレハロース / 医学物理学 / 放射線線量計 / 子宮頸癌治療 / 密封小線源治療 / 放射線治療 / 精度検証 / インビボ測定 / 直腸線量 / OSL線量計 / 子宮頸がん治療 / 被曝線量 / リスク臓器 / 放射線計測 / 軟部腫瘍 / アミノ酸代謝 / PET/CT / テクスチャ解析 / PET / フォトンカウンティング / X線診断 / 定量画像生成 / 画像解析アルゴリズム

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