Öğretici Akın, Çakır Aydın, Akbaş Uğur, Köksal Canan, Kalafat Ümmühan, Tambaş Makbule, Bilge Hatice
Department of Basic Oncology, Institute of Medical Sciences, Istanbul University, Istanbul, Turkey.
Department of Radiation Oncology, Memorial Hospital, Istanbul, Turkey.
J Med Phys. 2017 Jul-Sep;42(3):128-132. doi: 10.4103/jmp.JMP_133_16.
This study aims to investigate the factors that reduce fetal dose in pregnant patients with breast cancer throughout their radiation treatment. Two main factors in a standard radiation oncology center are considered as the treatment planning systems (TPSs) and simple shielding for intensity modulated radiation therapy technique.
TPS factor was evaluated with two different planning algorithms: Anisotropic analytical algorithm and Acuros XB (external beam). To evaluate the shielding factor, a standard radiological purpose lead apron was chosen. For both studies, thermoluminescence dosimeters were used to measure the point dose, and an Alderson RANDO-phantom was used to simulate a female pregnant patient in this study. Thirteen measurement points were chosen in the 32 slice of the phantom to cover all possible locations of a fetus up to 8 week of gestation.
The results show that both of the TPS algorithms are incapable of calculating the fetal doses, therefore, unable to reduce them at the planning stage. Shielding with a standard lead apron, however, showed a slight radiation protection (about 4.7%) to the fetus decreasing the mean fetal dose from 84.8 mGy to 80.8 mGy, which cannot be disregarded in case of fetal irradiation.
Using a lead apron for shielding the abdominal region of a pregnant patient during breast irradiation showed a minor advantage; however, its possible side effects (i.e., increased scattered radiation and skin dose) should also be investigated further to solidify its benefits.
本研究旨在调查在乳腺癌孕妇整个放射治疗过程中降低胎儿剂量的因素。在标准放射肿瘤学中心，两个主要因素被认为是治疗计划系统（TPS）和适用于调强放射治疗技术的简单屏蔽。
使用两种不同的计划算法评估TPS因素：各向异性分析算法和Acuros XB（外照射）。为了评估屏蔽因素，选择了标准的放射学用途铅围裙。在这两项研究中，使用热释光剂量计测量点剂量，并使用Alderson RANDO体模在本研究中模拟怀孕女性患者。在体模的32层中选择了13个测量点，以覆盖妊娠8周内胎儿的所有可能位置。
结果表明，两种TPS算法都无法计算胎儿剂量，因此在计划阶段无法降低胎儿剂量。然而，使用标准铅围裙进行屏蔽对胎儿显示出轻微的辐射防护作用（约4.7%），将胎儿平均剂量从84.8 mGy降至80.8 mGy，在胎儿受照射的情况下，这一点不容忽视。
在乳腺癌放疗期间使用铅围裙屏蔽孕妇腹部区域显示出一定的优势；然而，其可能的副作用（即增加散射辐射和皮肤剂量）也应进一步研究以巩固其益处。
