研究者詳細 - 小山　修司

論文 - 小山　修司

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Detail analysis of dose distribution in phantom in X-ray CT using EGS5

HABA Tomonobu, KOYAMA Shuji

Proceedings of the Eighteenth EGS User's Meeting in Japan 頁： 58-61 2011年10月

Simulation of X-ray CT using Monte Carlo method

MORISHITA Yuki, KOYAMA Shuji

Proceedings of Joint International Conference on Supercomputing in Nuclear Applications and Monte Carlo 2010 頁： USB-Memory E6 10304.pdf 2010年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

The purpose of this study is to calculate accurate radiation exposure doses in patient using voxel phantom and incorporating specific effects of x-ray radiation in x-ray CT examination. In x-ray CT, a special filter called beam-shaping filter is positioned in front of x-ray tube. As the other factor, CT table reduces radiation dose. These factors were measured and incorporated in simulation code of Electron Gamma Shower version 5 (EGS5). Difference of measurement and calculation based on CT Dose Index (CTDI) in an acrylic cylindrical phantom was within 2.8 %. Detailed dose distribution in the voxel anthropomorphic phantom was obtained using the simulation. Measurement and calculation of organ doses denoted the same tendency of the location in the phantom, but near the end of scan area the calculation value was smaller than the measurement value. In the measurement, organ dose was under estimated by partial irradiation of the organ at the border of scan area.

医療被ばく測定テキストにおける小さな疑問，大きなわだかまりを解決しよう-X線CT-

小山修司

日本放射線技術学会計測分科会誌 18 巻 ( 2 ) 頁： 36-40 2010年11月

Estimation pf patient exposure doses using anthropomorphic phantom undergoing X-ray CT examination

MORISHITA Yuki, KOYAMA Shuji

Proceedings of the Seventeenth EGS Users' Meeting in Japan 頁： 82-88 2010年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

The purpose of this study is to calculate accurate radiation exposure doses in anthropomorphic phantom using voxel thchnique and incorporating specific effects of x-ray radiation in x-ray CT examination. In x-ray CT, a special filter called beam-shaping filter is positioned in front of x-ray tube. As the other factor, CT table reduces radiation dose. These factors were measured and incorporated in simulation code of Electron Gamma Shower version 5 (EGS5). Difference of measurement and calculation based on CT Dose Index (CTDI) in an acrylic cylindrical phantom was within 2.8 %. Detailed dose distribution in the voxel anthropomorphic phantom was obtained using the simulation. Measurement and calculation of organ doses denoted the same tendency of the location in the phantom, but near the end of scan area the calculation value was smaller than the measurement value. In the measurement, organ dose was under estimated by partial irradiation of the organ at the border of scan area.

Patient radiation dose in prospectively gated axial CT coronary angiography and retrospectively gated helical technique with a 320-detector row CT scanner 査読有り

SEGUCHI Shigenobu, AOYAMA Takahiko, KOYAMA Shuji, FUJII Keisuke, YAMAUCHI-KAWAURA Chiyo

Med Phys 37 巻 ( 11 ) 頁： 5579-5585 2010年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

PMID: 21158269

PURPOSE: The aim of this study was to evaluate radiation dose to patients undergoing computed tomography coronary angiography (CTCA) for prospectively gated axial (PGA) technique and retrospectively gated helical (RGH) technique.

METHODS: Radiation doses were measured for a 320-detector row CT scanner (Toshiba Aquilion ONE) using small sized silicon-photodiode dosimeters, which were implanted at various tissue and organ positions within an anthropomorphic phantom for a standard Japanese adult male. Output signals from photodiode dosimeters were read out on a personal computer, from which organ and effective doses were computed according to guidelines published in the International Commission on Radiological Protection Publication 103.

RESULTS: Organs that received high doses were breast, followed by lung, esophagus, and liver. Breast doses obtained with PGA technique and a phase window width of 16% at a simulated heart rate of 60 beats per minute were 13 mGy compared to 53 mGy with RGH technique using electrocardiographically dependent dose modulation at the same phase window width as that in PGA technique. Effective doses obtained in this case were 4.7 and 20 mSv for the PGA and RGH techniques, respectively. Conversion factors of dose length product to the effective dose in PGA and RGH were 0.022 and 0.025 mSv mGy(-1) cm(-1) with a scan length of 140 mm.

CONCLUSIONS: CTCA performed with PGA technique provided a substantial effective dose reduction, i.e., 70%-76%, compared to RGH technique using the dose modulation at the same phase windows as those in PGA technique. Though radiation doses in CTCA with RGH technique were the same level as, or some higher than, those in conventional coronary angiography (CCA), the use of PGA technique reduced organ and effective doses to levels less than CCA except for breast dose.

Radiation dose evaluation in tomosynthesis and C-arm cone-beam CT examinations with an anthropomorphic phantom 査読有り

KOYAMA Shuji, AOYAMA Takahiko, ODA Nobuhiro, YAMAUCHI-KAWAURA Chiyo

Med Phys 37 巻 ( 8 ) 頁： 4298-4306 2010年8月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Access below to see full text;
http://ir.nul.nagoya-u.ac.jp/jspui/handle/2237/14184

PMID: 20879590

PURPOSE: The objective of this study was to evaluate organ dose and the effective dose to patients undergoing tomosynthesis (TS) and C-arm cone-beam computed tomography (CBCT) examinations and to compare the doses to those in multidetector CT (MDCT) scans.

METHODS: Patient doses were measured with small sized silicon-photodiode dosimeters, 48 in number, which were implanted at various tissue and organ positions within an anthropomorphic phantom. Output signals from photodiode dosimeters were read out on a personal computer, from which organ and effective doses were computed. The doses in head, chest, abdomen, and hip-joint TS, and in head and abdomen C-arm CBCT were evaluated for routine protocols on Shimadzu TS and C-arm CBCT systems, and the doses in MDCT with the same scan regions as in TS and CBCT were on Toshiba 64-detector-row CT scanners.

RESULTS: In TS examination of the head, chest, abdomen, and hip-joint, organ doses for organs within scan ranges were 1-4 mGy, and effective doses were 0.07 mSv for the head scan and around 1 mSv for other scans. In C-arm CBCT examinations of the head and abdomen, organ doses within scan range were 2-37 mGy, and effective doses were 1.2 mSv for the head scan and 4-5 mSv for abdominal scans. Effective doses in TS examinations were approximately a factor of 10 lower, while the doses in CBCT examinations were nearly the same level, compared to the doses in the corresponding MDCT examinations.

CONCLUSIONS: TS examinations with low doses and excellent resolutions in coronal images compared to recent MDCT would widely be used in tomographic examinations of the chest, abdomen, pelvis, skeletal-joints, and knee instead of MDCT examinations with significantly high doses. Since patient dose in C-arm CBCT was nearly the same level as that in recent MDCT, the same consideration for high radiation dose would be required for the use of CBCT.

口腔および顎顔面エックス線撮影における唾液腺に着目した実効線量評価査読有り

岡野恒一，松尾綾江，後藤賢一，横井みどり，蛭川亜希子，奥村信次，小山修司

日本放射線技術学会雑誌 65 巻 ( 5 ) 頁： 594-602 2009年5月

記述言語：日本語掲載種別：研究論文（学術雑誌）

口腔外科領域の被曝線量評価のため，人体ファントム内に線量計を配置し，各部の臓器線量を求めた。これに，放射線荷重係数と組織荷重係数を乗じ積算すると実効線量となる。ICRP1990年Pub.60による組織荷重係数に対し，2007年Pub.103のそれでは，新しく唾液腺などが加わり，この前後の違いを検討した結果，前者に対して後者の実効線量は，口内撮影で1.6～4.5倍，パノラマ法で約2.2倍高くなった。

植込み型心臓ペースメーカおよび植込み型除細動器に対する診断Ｘ線の影響とその対策査読有り

小田敍弘，中島　博，安倍治彦，小山修司，掛田伸吾，興梠征典

日本放射線技術学会雑誌 64 巻 ( 7 ) 頁： 805-813 2008年7月

Evaluation of exposure dose to patiensts undergoing catheter ablation procedures - a phantom study 査読有り

Sigenobu Seguchi, Takahiko Aoyama, Shuji Koyama, Chiyo Kawaura, Keisuke Fujii

Europian Radiology 18 巻頁： 2559-2567 2008年5月

X線CTの被曝

小山修司

総合臨床 57 巻 ( 4 ) 頁： 766-768 2008年4月

Analysis of x-ray energy change at various points in two types of cylindrical phantome undergoing x-ray CT scan using monte carlo simulation

Yuya Sasada, Shuji Koyama

Proceedings of the Fourteenth EGS Users' Meeting in Japan 頁： 92-101 2007年11月

動的輪郭モデルを用いた側脳室下角領域抽出法の改良査読有り

服部真澄，小山修司，小寺吉衞

日本放射線技術学会雑誌 63 巻 ( 8 ) 頁： 862-870 2007年8月

記述言語：日本語掲載種別：研究論文（学術雑誌）

アルツハイマー型痴呆を，X線CTの頭部画像より自動計測により診断支援するシステムを開発している．このシステムでは，しきい値処理に基づき，側脳室下角を自動検出しているが少なからず誤検出が見受けられた．本研究では，輪郭抽出法に着目し，動的輪郭モデルSnakesを一部改良し取り入れた．これにより，側脳室下角をより良好に抽出することができた．（小寺吉衞教授との共同研究）

Comparative evaluation of organ and effective doses for paediatric patients with those for adults in chest and abdominal CT examinations 査読有り

Keisuke Fujii,Takahiko Aoyama, Shuji Koyama, Chiyo Kawaura

British Journal of Radiology 80 巻 ( 8 ) 頁： 657-667 2007年8月

Automated measurement of medial temporal lobe atrophy by computed tomography 査読有り

Masumi Hattori,Shuji Koyama,Yoshie Kodera,Yosuke Kogure,Yasushi Ido,Hirofumi Asano

International Journal of Computer Assisted Radiology and Surgery, DOI10.1007/s11548-007-0071-y 頁： 321-330 2007年2月

人体ファントム線量計測に基づいた冠動脈造影と冠動脈インターベンション術における患者の被曝線量評価査読有り

瀬口繁信，青山隆彦，小山修司，川浦稚代

保健物理 41 巻 ( 4 ) 頁： 234-248 2006年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）

狭心症や虚血性心疾患の検査や治療に用いられる冠動脈造影，冠動脈IVRでは，専用の血管造影装置を用い比較的長時間の手技を行う．近年，この手技による，放射線皮膚障害が何件か報告されており，患者被曝が問題となっている．本研究では，人体ファントムと半導体線量計による計測システムを用い，これらの手技における皮膚線量や臓器・組織線量を測定した．皮膚線量では1.4Gy程度，実効線量では最大44mGyであった．（青山隆彦教授，川浦稚代助教との共同研究）

CT被曝の評価と問題点招待有り

小山修司，青山隆彦，川浦稚代，藤井啓輔

臨床放射線 51 巻 ( 13 ) 頁： 1811-1819 2006年12月

担当区分：筆頭著者記述言語：日本語

X線CTの被曝線量評価について，従来の方法としてのCTDIやDLPによる方法と人体の被ばくを表す臓器線量の測定方法について述べた．後者の方法により測定された様々なモダリティでの臓器線量を示し，本法における様々な問題点について示した．特に，このような測定法に換えて，モンテカルロシミュレーションによる推定などがあるが，数学ファントムの体型の違いなどにより測定値と一致しないことが起こった．

Patient Exposure Dose Delivered by Modern Multi-Detector Helical Computed Tomography

Shuji Koyama,Keisuke Fujii,Takahiko Aoyama,Chiyo Kawaura

The Second Asian Oceanic Congress for Radiation Protection Proceeding(CD-ROM) 頁： 1376-1379 2006年10月

CTDI再入門

小山修司

日本放射線技術学会計測分科会誌 14 巻 ( 2 ) 頁： 68-74 2006年10月

Patient Exposure Dose Delivered by Modern Multi-Detector Helical Computed Tomography

Shuji Koyama,Keisuke Fujii,Takahiko Aoyama,Chiyo Kawaura

The Second Asian Oceanic Congress for Radiation Protection Proceeding(CD-ROM) 頁： 1376-1379 2006年10月

Organ and Effective Dose Evaluation in Diagnostic Radiology Based on In-phantom Dose Measurements with Novel Photodiode-dosimeters 査読有り

Chiyo Kawaura,Takahiko Aoyama,Shuji Koyama,Masataka Achiwa,Masaki Mori

Radiation Protection Dosimetry 118 巻 ( 4 ) 頁： 421-430 2006年1月

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