左侧内乳链放疗中使用光子和电子射野时的心脏风险及MCNP/SISCODES剂量
Cardiac risk and MCNP/SISCODES doses in RT of the left internal mammary chain with photon and electron portals.
作者信息
Campos Tarcisio Passos Ribeiro de, Mendes Bruno M, Trindade Bruno, Araujo Wagner L
机构信息
Programa de Ciências e Técnicas Nucleares, Departamento de Engenharia Nuclear, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, EE, Bloco 4, S.2285, CEP: 31270901, Belo Horizonte, MG, Brazil.
Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN), Av. Presidente Antônio Carlos, 6.627, CEP 31270-901, Belo Horizonte, MG, Brazil.
出版信息
Rep Pract Oncol Radiother. 2018 Sep-Oct;23(5):384-391. doi: 10.1016/j.rpor.2018.07.004. Epub 2018 Aug 13.
AIM
The present study evaluated the increment of cardiac risk (CR) and absorbed dose in radiotherapy of the internal mammary chain (IMC), in particular with photon portals of 4 6 MV, and cobalt therapy (Co60); and, electron portals of 8, 12 and 16 MeV applied in the left breast, considering the adoption of a combined photon (16 Gy) and electron (30 Gy) protocols.
MATERIALS AND METHODS
The modified ICRP-reference female model of 60 kg, 163 cm and 43 years of age, coil RCP-AF, was modelled. The MCNP6/SICODES codes were employed, where the spatial dose distributions and dose-volume histograms were generated. Toxicity limits and a CR model were considered.
RESULTS
CR associated with the 6 MV, 4 MV and Co60 portals increased 41.1; 40.6 and 34.5%, respectively; while, in 8, 12 and 16 MeV portals, they were 5.0, 32.5 and 49.2%, respectively. High anomalous scatter radiation from electron portals was found in the left lung providing an average dose of 3.3-5.0 Gy.
CONCLUSIONS
To RCP-AF, the Co60 portal for IMC-RT presented more attractive dose distribution, whose 16 Gy for photon-component produced less CR increase, 5% lower than the other photon portals. Considering electron portals, the smallest CR increase was produced by 8 MeV portal while 12-16 MeV made the risk higher. There is a call for a less hardened energetic spectrum in order to reduce CR; however, holding suitable IMC penetration. A combined Co60/8-12 MeV may bring benefits, reducing CR. The lowest risk was found to 46 Gy electron portals exclusively.
目的
本研究评估了内乳链（IMC）放射治疗中心脏风险（CR）的增加以及吸收剂量，特别是使用4、6 MV光子射野和钴治疗（Co60）时；以及应用于左乳的8、12和16 MeV电子射野，考虑采用光子（16 Gy）和电子（30 Gy）联合方案的情况。
材料与方法
对体重60 kg、身高163 cm、年龄43岁的改良国际放射防护委员会（ICRP）参考女性模型（线圈RCP - AF）进行建模。使用MCNP6/SICODES代码生成空间剂量分布和剂量体积直方图。考虑了毒性限值和CR模型。
结果
与6 MV、4 MV和Co60射野相关的CR分别增加了41.1%、40.6%和34.5%；而在8、12和16 MeV射野中，分别为5.0%、32.5%和49.2%。在左肺发现电子射野产生的高异常散射辐射，平均剂量为3.3 - 5.0 Gy。
结论
对于RCP - AF，IMC - RT的Co60射野呈现出更具吸引力的剂量分布，其光子部分的16 Gy产生的CR增加较少，比其他光子射野低5%。考虑电子射野，8 MeV射野产生的CR增加最小，而12 - 16 MeV使风险更高。需要更软的能谱以降低CR；然而，要保持对IMC的适当穿透。Co60/8 - 12 MeV联合使用可能会带来益处，降低CR。仅46 Gy电子射野的风险最低。
Zotero 插件