医療科学部
基本情報
研究キーワード
2研究分野
1学歴
2-
- 2000年
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- 1975年
委員歴
3-
1998年 - 2005年
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1988年 - 1992年
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1981年 - 1983年
受賞
4-
2012年
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2002年
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1994年
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1989年
論文
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日本放射線技術学会雑誌 72(10) 1007-1014 2016年10月 査読有り<p>The diagnostic reference levels (DRLs) of the general X-ray radiography are defined by the absorbed dose of air at the entrance surface with backscattered radiation from a scattering medium. Generally, the entrance surface dose of the general X-ray radiography is calculated from measured air kerma of primary X-ray multiplied by a backscatter factor (BSF). However, the BSF data employed at present used water for scattering medium, and was calculated based on the water-absorbed dose by incident primary photons and backscattered photons from the scattering medium. In the calculation of air dose at the entrance surface defined in DRLs, there are no theoretical consistencies for using BSF based on water dose, and this may be a cause of calculation error. In this paper, we verified the difference in BSF by the difference in the scattering medium and by the difference in the objective dose by means of the Monte Carlo simulation. In this calculation, the scattering medium was set as water and the soft-tissue, and the objective dose was set as air dose, water dose, soft-tissue dose, and skin dose. The difference in BSF calculated by the respective combination was at most about 1.3% and was less than 1% in most cases. In conclusion, even if the entrance surface dose defined by DRLs of general X-ray radiography is calculated using BSF, which set both the scattering medium and the object substance of the absorbed dose as water, a so big error doesn't show.</p>
MISC
66-
日本放射線技術学会雑誌 66(6) 599-608 2010年In medical linear accelerators, radioactivation is induced on the target and neighborhood parts by photoneutrons accompanying a photo-nuclear reaction and leading to higher acceleration energy. We measured the residual radiation from the radioactivated materials according to the time, and tried to identify radioactivated nuclides and their relative quantities by means of measurement results. It was presumed that the main source of residual radiations was the Target, Flattening filter and Primary collimator in the linac head. Among those materials (copper, tungsten), we calculated decrement curves of residual radiations from radioactivated nuclides generated with photo-nuclear reaction or thermal neutron capture reaction by various ratios, and we investigated the ratio that best fit the measured data. Consequently, it was presumed that 66Cu generated with thermal neutron capture reaction contributed the most to residual radiation, followed by 62Cu generated with photo-nuclear reaction contributed. It is important to understand various characteristics of these nuclides and to undertake management of the device.
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日本放射線技術学会雑誌 66(5) 495-501 2010年The characteristics of activation after high-energy X-rays have been generated by medical linear accelerators were measured using an ionization chamber. Radiation doses increased with rising X-ray energy, based on 10 MV, 15 MV, and 18 MVX-ray measurements. When the total irradiation dose was changed, radiation dose increased with total irradiation dose. When the collimator opened, the radiation dose at a position 15 cm from the isocenter reached about the maximum, which was 2.2 times the dose at the isocenter. The radiation dose became about 0.3 times its level at a position 40 cm from the isocenter, in the outer irradiation field. The dose distribution in the treatment room became almost the same dose extending from the isocenter to 200 cm. Radiation dose decreased gradually while moving away from the target on the treatment beam axis. But it increased again as it approached the floor face. The occupational exposure dose, which was presumed from measurements of the radiation dose 50 cm from the isocenter, was about 0.9 mSv during a year, assuming 600 MU for 1 person, 8 people a day, and 245 days a year. Radiation dose changed with X-ray energy in the machine used, and it was a geometrical constituent in the treatment room. It is important to understand the characteristics of radiation generated by medical linear accelerators.
所属学協会
3Works(作品等)
3共同研究・競争的資金等の研究課題
4教育方法・教育実践に関する発表、講演等
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件名自作ソフトウェアによる放射線基礎科学の学習支援(第２回藤田保健衛生大学医療科学部相互研修ＦＤ)終了年月日2009/08概要放射線医療は、放射線と人体との相互作用による物理現象を利用したものである。放射線の多種多様な物理現象を理解するためには、膨大な物理データ、その取扱い方法の習得が必要となる。放射線学科学生の学習支援を目的に、放射線に関する種々の物理データおよびその取扱い、それらを用いた放射線基礎科学に関するコンピュータソフトウェアを作成した。その概要について報告した。