Ozaki Y, Watanabe H, Kaida A, Miura M, Nakagawa K, Toda K, Yoshimura R, Sumi Y, Kurabayashi T
Department of Oral and Maxillofacial Radiology, Graduate School, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo, 113-8549, Japan.
Department of Oral Radiation Oncology, Graduate School, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo, 113-8549, Japan.
J Radiat Res. 2017 Jul 1;58(4):523-528. doi: 10.1093/jrr/rrx002.
Early stage oral cancer can be cured with oral brachytherapy, but whole-body radiation exposure status has not been previously studied. Recently, the International Commission on Radiological Protection Committee (ICRP) recommended the use of ICRP phantoms to estimate radiation exposure from external and internal radiation sources. In this study, we used a Monte Carlo simulation with ICRP phantoms to estimate whole-body exposure from oral brachytherapy. We used a Particle and Heavy Ion Transport code System (PHITS) to model oral brachytherapy with 192Ir hairpins and 198Au grains and to perform a Monte Carlo simulation on the ICRP adult reference computational phantoms. To confirm the simulations, we also computed local dose distributions from these small sources, and compared them with the results from Oncentra manual Low Dose Rate Treatment Planning (mLDR) software which is used in day-to-day clinical practice. We successfully obtained data on absorbed dose for each organ in males and females. Sex-averaged equivalent doses were 0.547 and 0.710 Sv with 192Ir hairpins and 198Au grains, respectively. Simulation with PHITS was reliable when compared with an alternative computational technique using mLDR software. We concluded that the absorbed dose for each organ and whole-body exposure from oral brachytherapy can be estimated with Monte Carlo simulation using PHITS on ICRP reference phantoms. Effective doses for patients with oral cancer were obtained.
早期口腔癌可通过口腔近距离放射疗法治愈，但此前尚未对全身辐射暴露状况进行研究。最近，国际放射防护委员会（ICRP）建议使用ICRP人体模型来估计来自外部和内部辐射源的辐射暴露。在本研究中，我们使用带有ICRP人体模型的蒙特卡罗模拟来估计口腔近距离放射疗法导致的全身暴露。我们使用粒子与重离子传输代码系统（PHITS）对含192铱发夹和198金颗粒的口腔近距离放射疗法进行建模，并在ICRP成人参考计算人体模型上进行蒙特卡罗模拟。为了验证模拟结果，我们还计算了这些小源的局部剂量分布，并将其与日常临床实践中使用的Oncentra手动低剂量率治疗计划（mLDR）软件的结果进行比较。我们成功获得了男性和女性各器官的吸收剂量数据。使用192铱发夹和198金颗粒时，性别平均当量剂量分别为0.547和0.710 Sv。与使用mLDR软件的另一种计算技术相比，PHITS模拟是可靠的。我们得出结论，使用PHITS在ICRP参考人体模型上进行蒙特卡罗模拟，可以估计口腔近距离放射疗法各器官的吸收剂量和全身暴露。获得了口腔癌患者的有效剂量。
