著者

松原 孝祐

出版者

公益社団法人 日本放射線技術学会

雑誌

放射線防護分科会会誌 (ISSN:13453246)

巻号頁・発行日

vol.38, pp.35-38, 2014-04-10 (Released:2017-12-29)

著者

松原 孝祐 Thunyarat CHUSIN 大久保 玲奈 小川 善紀

出版者

日本保健物理学会

雑誌

保健物理 (ISSN:03676110)

巻号頁・発行日

vol.53, no.4, pp.238-246, 2018 (Released:2019-03-03)

参考文献数

39

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Evaluation of radiation dose from medical exposure is important because the use of ionizing radiation in medical field contributes significantly to the exposure of the population. In plain radiography, the entrance skin dose, which is absorbed by the skin as it reaches the patient, is generally estimated. It is calculated from the air kerma at the same focus skin distance on the beam central axis measured with a dosimeter. In fluoroscopy, the indirect monitoring using dose-area product meter is generally performed for estimating the entrance skin dose in real-time to avoid skin injuries. In mammography, the average glandular dose is estimated because mammary glands have more sensitive to radiation than skin. The European Organization for Quality-Assured Breast Screening and Diagnostic Services protocol has been used to estimate average glandular dose from full-field digital mammography in Japan. Although volume CT dose index or dose-length product, as seen on CT consoles, do not represent the actual dose for the patient, they are measured to assist in quality control and optimization as well as the air kerma rate at the patient entrance reference point in fluoroscopy and the average glandular dose in mammography. For the purpose of patient dose evaluation, physical dose measurements using an anthropomorphic phantom and Monte Carlo simulations can estimate patient organ doses from medical exposure.

著者

越田 吉郎 曽田 卓実 能登 公也 福田 篤志 松原 孝祐 中川 浩人 川端 千香子

出版者

公益社団法人 日本放射線技術学会

雑誌

日放技学誌 (ISSN:03694305)

巻号頁・発行日

vol.61, no.7, pp.989-996, 2005

参考文献数

20

被引用文献数

1 4

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Medical personnel involved in abdominal angiography are exposed not only to direct radiation but also scattered radiation from inspection tables, patients, image intensifiers, and the beam-limiting system (collimator), among others. Japanese standard JISZ4831 prescribes protective coats of at least 0.25mm lead equivalent, which is the uniform thickness of lead equivalent. The most commonly used protective coats are 0.25mm Pb, 0.35mm Pb, or 0.5mm Pb in thickness. The weight of a typical protective coat is about 3kg. While some coats weigh up to 6kg, wearing such heavy coats becomes physically burdensome as inspection time increases. The trade-off between physical burden and protection was considered by analyzing the X-ray intensity distribution and attenuation rate of scattered radiation in each position assumed by the medical staff. In the case of inspections performed at an x-ray tube voltage of 80kV, it may be possible to reduce the weight of the lead rubber apron by about 33%. Namely, the lead thickness can be reduced uniformly by 0.20mm Pb at 70cm and 0.05mm Pb at 100cm, when the shielding capability of a 0.25mm thick Pb layer is accepted as the standard at 40cm above the gonad position. The same range of permeated X-ray dose for the gonad position may be reduced as well. In the case of 110kV, when the lead thicknesses are 0.30mm Pb at 40cm and 70cm, and 0.10mm Pb at 100cm, it is possible to reduce the weight of the lead rubber apron by about 28%.

著者

越田 吉郎 曽田 卓実 能登 公也 福田 篤志 松原 孝祐 中川 浩人 川端 千香子

出版者

公益社団法人日本放射線技術学会

雑誌

日本放射線技術學會雜誌 (ISSN:03694305)

巻号頁・発行日

vol.61, no.7, pp.989-996, 2005-07-20

被引用文献数

1

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Medical personnel involved in abdominal angiography are exposed not only to direct radiation but also scattered radiation from inspection tables, patients, image intensifiers, and the beam-limiting system (collimator), among others. Japanese standard JISZ4831 prescribes protective coats of at least 0.25mm lead equivalent, which is the uniform thickness of lead equivalent. The most commonly used protective coats are 0.25mm Pb, 0.35mm Pb, or 0.5mm Pb in thickness. The weight of a typical protective coat is about 3kg. While some coats weigh up to 6kg, wearing such heavy coats becomes physically burdensome as inspection time increases. The trade-off between physical burden and protection was considered by analyzing the X-ray intensity distribution and attenuation rate of scattered radiation in each position assumed by the medical staff. In the case of inspections performed at an x-ray tube voltage of 80kV, it may be possible to reduce the weight of the lead rubber apron by about 33%. Namely, the lead thickness can be reduced uniformly by 0.20mm Pb at 70cm and 0.05mm Pb at 100cm, when the shielding capability of a 0.25mm thick Pb layer is accepted as the standard at 40cm above the gonad position. The same range of permeated X-ray dose for the gonad position may be reduced as well. In the case of 110kV, when the lead thicknesses are 0.30mm Pb at 40cm and 70cm, and 0.10mm Pb at 100cm, it is possible to reduce the weight of the lead rubber apron by about 28%.

著者

酒向 健二 松原 孝祐 松本 真

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.77, no.3, pp.284-292, 2021 (Released:2021-03-20)

参考文献数

22

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Purpose: A volume scan can cover a range of 160 mm with a single gantry rotation. It can be performed sequentially (a wide volume [WV] scan) to cover more than 160 mm, and volume Xact+ (Xact+) can be used when volume scan is done to extend the reconstruction area. The purpose of this study was to investigate the dose distribution and organ doses for a WV scan during chest CT. Method: We arranged radiophotoluminescence glass dosimeters (RPLDs) linearly on the surface and inside of the phantom to evaluate the dose distribution along the z-axis. We also placed RPLDs at the lens, thyroid, and breast positions to evaluate organ doses. We performed WV and helical scans and WV scan using Xact+. Result: The absorbed doses increased at the borders of the volume scans, and dose peaks were observed there. The organ doses for the WV scan outside the acquisition range were lower than those for the helical scan. The organ doses inside the acquisition range changed by the locations of borders. Conclusion: The WV scan increases the absorbed doses at the overlapping scanned regions, which can be reduced by using Xact+.

著者

髙田 光雄 松原 孝祐 越田 吉郎 太郎田 融

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.71, no.4, pp.332-337, 2015 (Released:2015-04-20)

参考文献数

14

被引用文献数

2 5

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The purpose of our study was to investigate radiation dose for lower tube voltage CT using automatic exposure control (AEC). An acrylic body phantom was used, and volume CT dose indices (CTDIvol) for tube voltages of 80, 100, 120, and 135 kV were investigated with combination of AEC. Average absorbed dose in the abdomen for 100 and 120 kV were also measured using thermoluminescence dosimeters. In addition, we examined noise characteristics under the same absorbed doses. As a result, the exposure dose was not decreased even when the tube voltage was lowered, and the organ absorbed dose value became approximately 30% high. And the noise was increased under the radiographic condition to be an equal absorbed dose. Therefore, radiation dose increases when AEC is used for lower tube voltage CT under the same standard deviation (SD) setting with 120 kV, and the optimization of SD setting is crucial.

著者

松原 孝祐

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.36, no.1, pp.62-66, 2016-05-31 (Released:2016-11-30)

参考文献数

28

著者

松原 孝祐

出版者

公益社団法人日本放射線技術学会

雑誌

放射線防護分科会会誌 (ISSN:13453246)

巻号頁・発行日

no.34, pp.6-12, 2012-04-12