Department of Physics, University of Bojnord, Bojnord, Iran.
Physics Department, Hakim Sabzevari University, Sabzevar, Iran.
Appl Radiat Isot. 2024 Dec;214:111532. doi: 10.1016/j.apradiso.2024.111532. Epub 2024 Sep 25.
Proton therapy is a rapidly progressing modality with a significant impact on lung cancer treatment. However, there are concerns about the subsequent effects of secondary radiation in out-of-field organs. Thus, the present study aimed to evaluate the risk of subsequent secondary cancers within non-target organs during proton therapy for lung cancer. A Monte Carlo model of the International Commission on Radiological Protection (ICRP) 110 male phantom was employed to calculate the absorbed dose associated with secondary photons and neutrons within out-of-field organs for different tumor locations. The risk of induced secondary cancers was then estimated using the Biological Effects of Ionizing Radiation Committee (BEIR) VII and National Council on Radiation Protection and Measurements (NCRP) 116 risk models. Organs close to the tumor, such as the heart, esophagus, thymus, and liver, received the highest equivalent doses. The calculated equivalent doses increased as the tumor depth increased from 4-8 cm to 12-16 cm. The contribution of neutrons to the total equivalent dose was dominant (up to 90%) in most of the organs studied. The calculated risks of secondary cancers were higher in the liver and esophagus compared with other organs when using the BEIR risk model. The maximum risk value was obtained for the left lung when the NCRP 116 risk model was used. Furthermore, the estimated risks of secondary malignancies increased with the tumor depth using both risk models. The calculated risks of radiation-induced secondary cancers were relatively lower than the baseline cancer risks. However, extra attention is warranted to minimize subsequent secondary cancers after proton therapy for lung cancer.
质子治疗是一种快速发展的模式，对肺癌治疗有重大影响。然而，人们对非靶区器官中二次辐射的后续影响存在担忧。因此，本研究旨在评估肺癌质子治疗中，非靶区器官内继发二次癌症的风险。本研究采用国际辐射防护委员会（ICRP）110 男性体模的蒙特卡罗模型，计算不同肿瘤位置时非靶区器官内二次光子和中子的吸收剂量。然后使用生物效应辐射委员会（BEIR）VII 和国家辐射防护与测量委员会（NCRP）116 风险模型来估计诱导继发癌症的风险。靠近肿瘤的器官，如心脏、食管、胸腺和肝脏，接受的当量剂量最高。随着肿瘤深度从 4-8cm 增加到 12-16cm，计算出的当量剂量也随之增加。在大多数研究的器官中，中子对总当量剂量的贡献（高达 90%）占主导地位。与其他器官相比，使用 BEIR 风险模型时，肝脏和食管的继发癌症风险更高。当使用 NCRP 116 风险模型时，左肺的最大风险值最高。此外，两种风险模型均显示，随着肿瘤深度的增加，继发恶性肿瘤的风险也随之增加。计算出的辐射诱导继发癌症的风险相对低于基线癌症风险。然而，对于肺癌质子治疗后继发二次癌症，需要额外关注以最小化其风险。
