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古渡 意彦*; 中上 晃一*; 土方 保和*; 山下 一太*; 平井 悠太*; 松崎 賢*; 盛武 敬*; 辻 智也; Zutz, H.*; Ketelhut, S.*; et al.
Radiation Protection Dosimetry, 201(9), p.663 - 671, 2025/06
被引用回数：0 パーセンタイル：0.00(Environmental Sciences)It is crucial to monitor healthcare workers' radiation exposure, especially given the increasing reliance on X-ray imaging technologies. In response to new evidence that the threshold for lens opacity is lower than previously thought, the International Commission on Radiological Protection (ICRP) has revised the annual dose limit for exposure to the lens of the eye. After the revision of the annual eye lens dose limit, the new survey on the dosemeter wearing rate was conducted in Japan. The result showed that despite the presence of monitoring protocols, the dosemeter wearing rate among healthcare workers was still low. Compliance often lacked robust verification measures, especially in smaller medical facilities. Active personal dosemeters (APDs) are commonly used in Japan, although studies suggest that they may underestimate exposure in certain settings, such as pulsed X-ray fields. Passive dosemeters, on the other hand, serve as legal dosemeters, offering a more accurate assessment of radiation exposure. This article addresses issues related to the monitoring of healthcare workers using APDs and clarifies concerns regarding the use of APDs by orthopedic surgeons during procedures involving high-dose X-ray exposure. A series of performance tests suggested that the APDs worn by orthopedic surgeons, who are often exposed to higher dose rates near patients, may underestimate radiation levels during procedures. This underestimation occurs because the surgeons are exposed to pulsed, scattered X-ray fields with energies ranging from 20 and 100 keV. The results also suggest monitoring techniques should be improved to ensure the safety of healthcare workers.
(0.07) for extremity dose monitoring of medical personnel古渡 意彦*; 吉富 寛; 永元 啓介*; 中上 晃一*; 盛武 敬*; 欅田 尚樹*
Radiation Protection Dosimetry, 199(15-16), p.1807 - 1812, 2023/10
被引用回数：0 パーセンタイル：0.00(Environmental Sciences)An additional individual monitoring using ring badge must be made, when inhomogenous exposure around radiation workers' extremity were critical for radiation workers. The RPLD, the GD-302M and the GD-352M have a dimension of 13.0 mm in length and 2.8 mm in diameter for outer casing and will also be a promising candidate for individual monitoring of the extremities of medical personnel. We investigated the applicability of this commercially available RPLDs to extremity dose monitoring by performing a characterization of the dosemeters by experiments and Monte Carlo (MC) calculations. The results shows that the energy response of GD-352M fully meets the IEC requirement between 20 keV and 200 keV. We also found that no significant angular dependence of responses for each model was observed and orientation of irradiation hardly affected the response. In conclusion, we demonstrated the applicability of a small RPLD to the extremity monitoring in terms of (0.07) for medical personnel.
古渡 意彦*; 永元 啓介*; 中上 晃一*; 吉富 寛; 盛武 敬*; 欅田 尚樹*
Radiation Protection Dosimetry, 198(17), p.1303 - 1312, 2022/10
被引用回数：2 パーセンタイル：21.09(Environmental Sciences)We demonstrate a practical calibration method and its applicability for a commercially available radiophotoluminescence dosemeter (RPLD, GD-352M) to eye lens dose monitoring, by performing the calibration in accord with the ISO recommendations. The calibration was then verified through a series of experiments. For verification of the derived calibration factor (1.21 
0.04, 
= 1) of the RPLD, we performed standard irradiations in the X-ray reference fields and the mockup measurements in the actual radiation fields in a hospital. The commercially available dosemeters, DOSIRIS was also put on the ISO cylinder phantom and the RANDO phantom together with the GD-352M in the verification experiments. The personal dose equivalents 
(3) obtained from the GD-352M and those obtained from the DOSIRIS were in good agreement with each other. Our results demonstrate the proper calibration of a commercially available RPLD that is applicable to the additional monitoring of the lens of the eyes for medical personnel.
古渡 意彦*; 永元 啓介*; 中上 晃一*; 谷村 嘉彦; 盛武 敬*; 欅田 尚樹*
Journal of Radiation Protection and Research, 47(1), p.39 - 49, 2022/03
For proper monitoring of the eye lens dose, an appropriate calibration factor of a dosimeter and information about the mean energies of X-rays are indispensable. The scattered X-ray energy spectra should be well characterized in medical practices where eye lenses of medical staffs might be high. Scattered X-ray energy spectra were experimentally derived for three different types of X-ray diagnostic and therapeutic equipment. A commercially available CdZnTe (CZT) spectrometer with a lead collimator was employed for the measurement of scattered X-rays. From the obtained energy spectra, the mean energies of the scattered X-rays lied between 40 and 60 keV. This also agreed with that obtained by the conventional half value layer method. The obtained mean energies of the scattered X-rays were found to match the flat region of the dosimeter response.
Sun, L.*; 稲葉 洋平*; 神崎 訓枝; Bekal, M.*; 千田 浩一*; 盛武 敬*
International Journal of Molecular Sciences (Internet), 21(3), p.812_1 - 812_12, 2020/01
被引用回数：10 パーセンタイル：34.16(Biochemistry & Molecular Biology)バイオドジメトリーは、電離放射線被ばく後の個人線量を推定するための有効な方法であり、これまで、血清, 血漿, 尿, 唾液などの非細胞性生体試料での代謝物をバイオドジメトリーのマーカーとして検討する研究が進められてきた。本研究では、非細胞性生体試料には反映されない健康状態や環境ストレスがあることから、血球の代謝物に注目し、キャピラリー電気泳動飛行時間質量分析法により、C57BL/6JマウスのX線照射後の血球の代謝産物を網羅的に調べた。結果として、血球中で106種類の代謝産物が被ばく後に有意に変化することがわかった。そのうち、有効なバイオマーカーとして、これまで報告されていなかった2'-deoxycytidine, choline, N6-acetyllysineを同定した。回帰分析等の結果から、血球の代謝物が予期しない事故などでの被曝線量推定に利用できる可能性を示唆した。
廣木 章博; 山下 真一*; 大城 佳子*; 盛武 敬*; 田口 光正
no journal, ,
これまで報告されているポリマーゲル線量計は、熱安定性に乏しいゼラチンゲルをマトリクスに、毒劇物のアクリルアミドをモノマーに用いて作製されている。本研究では、電子線照射により得たHPCゲルを低毒性のメタクリル酸エステルモノマー:2-ヒドロキシエチルメタクリレート(HEMA)、ポリエチレングリコールジメタクリレート(9G)、及び酸素除去剤:テトラキスヒドロキシメチルホスホニウムクロリド(THPC)から成る所定濃度のモノマー水溶液に浸漬後、真空パックし、ポリマーゲル線量計を作製した。ポリマーゲル線量計に
線を照射し、吸光度測定から白濁度合いの線量応答性を評価した結果、吸光度は5Gyまでの線量増加に伴いほぼ直線的に増加した。線量に対する吸光度の増分から算出した放射線感度は、9Gの濃度が高いほど高い値を示した。モノマー溶液中のHEMAと9G濃度を一定にし、THPC濃度を調節した結果、THPC濃度が高いほど放射線感度は増加した。したがって、9G, THPC濃度を最適化することで、ポリマーゲル線量計の放射線感受性を向上できることがわかった。また、治療用LINACからのX線をポリマーゲル線量計に照射した結果、治療計画の照射野と白濁した領域が一致することを確認した。
