近距离放射治疗期间施源器金属对剂量分布的影响。

Influence of metal of the applicator on the dose distribution during brachytherapy.

作者信息

Wu Chin-Hui, Shiau An-Cheng, Liao Yi-Jen, Lin Hsin-Yu, Liu Yen-Wan Hsueh, Hsu Shih-Ming

机构信息

Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan, ROC.

Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, ROC; Department of Radiation Oncology, Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan, ROC.

出版信息

PLoS One. 2014 Aug 18;9(8):e104831. doi: 10.1371/journal.pone.0104831. eCollection 2014.

DOI:10.1371/journal.pone.0104831

PMID:25133789

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4136780/

Abstract

This study explores how the metal materials of the applicator influence the dose distribution when performing brachytherapy for cervical cancer. A pinpoint ionization chamber, Monte Carlo code MCNPX, and treatment planning system are used to evaluate the dose distribution for a single Ir-192 source positioned in the tandem and ovoid. For dose distribution in water with the presence of the tandem, differences among measurement, MCNPX calculation and treatment planning system results are <5%. For dose distribution in water with the presence of the ovoid, the MCNPX result agrees with the measurement. But the doses calculated from treatment planning system are overestimated by up to a factor of 4. This is due to the shielding effect of the metal materials in the applicator not being considered in the treatment planning system. This result suggests that the treatment planning system should take into account corrections for the metal materials of the applicator in order to improve the accuracy of the radiation dose delivered.

摘要

本研究探讨了施源器的金属材料在宫颈癌近距离放射治疗过程中如何影响剂量分布。使用针点电离室、蒙特卡罗代码MCNPX和治疗计划系统来评估位于施源器管和卵形容器中的单个铱-192源的剂量分布。对于存在施源器管时水中的剂量分布，测量值、MCNPX计算结果与治疗计划系统结果之间的差异小于5%。对于存在卵形容器时水中的剂量分布，MCNPX结果与测量值一致。但治疗计划系统计算出的剂量高估了多达4倍。这是因为治疗计划系统未考虑施源器中金属材料的屏蔽效应。该结果表明，治疗计划系统应考虑对施源器金属材料进行校正，以提高所输送辐射剂量的准确性。