Pimenta Elsa Bifano, Nogueira Luciana Batista, de Campos Tarcísio Passos Ribeiro
Department of Nuclear Engineering, Federal University of Minas Gerais, Belo Horizonte, Brazil.
Department of Anatomy and Image, Federal University of Minas Gerais, Belo Horizonte, Brazil.
Rep Pract Oncol Radiother. 2021 Apr 14;26(2):242-250. doi: 10.5603/RPOR.a2021.0037. eCollection 2021.
The anthropomorphic and anthropometric phantom developed by the research group NRI (Núcleo de Radiações Ionizantes) can reproduce the effects of the interactions of radiation occurring in the human body. The whole internal radiation transport phenomena can be depicted by film dosimeters in breast RT. Our goal was to provide a dosimetric comparison of a radiation therapy (RT) plan in a 4MV 3D-conformal RT (4MV-3DCR T) and experimental data measured in a breast phantom.
The RT modality was two parallel opposing fields for the left breast with a prescribed dose of 2.0 Gy in 25 fractions. The therapy planning system (TPS) was performed on CA T3D software. The dose readings at points of interest (POI) pre-established in TPS were recorded. An anthropometric thorax-phantom with removal breast was used. EBT2 radiochromic films were inserted into the ipisilateral breast, contralateral breast, lungs, heart and skin. The irradiation was carried out on 4/80 Varian linear accelerator at 4MV.
The mean dose at the OAR's presented statistically significant differences (p < 0.001) of 34.24%, 37.96% and 63.47% for ipsilateral lung, contralateral lung, and heart, respectively. The films placed at the skin-surface interface in the ipsilateral breast also showed statistically significant differences (p < 0.001) of 16.43%, -10.16%, -14.79% and 15.67% in the four quadrants, respectively. In contrast, the PTV dosimeters, representative of the left breast volume, encompassed by the electronic equilibrium, presented a non-significant difference with TPS, p = 0.20 and p = 0.90.
There was a non-significant difference of doses in PTV with electronic equilibrium; although no match is achieved outside electronic equilibrium.
由NRI（电离辐射核心小组）研究团队开发的人体形态和人体测量模型能够再现人体中发生的辐射相互作用的影响。乳腺放疗中，整个内部辐射传输现象可用薄膜剂量仪来描述。我们的目标是对4MV三维适形放疗（4MV-3DCRT）中的放射治疗（RT）计划与在乳腺模型中测量的实验数据进行剂量学比较。
放疗方式为针对左侧乳腺的两个平行相对野，处方剂量为2.0Gy，分25次照射。在CAT3D软件上进行治疗计划系统（TPS）操作。记录在TPS中预先设定的感兴趣点（POI）处的剂量读数。使用了一个去除乳房的人体测量胸部模型。将EBT2放射变色薄膜插入同侧乳房、对侧乳房、肺部、心脏和皮肤中。在4MV的4/80瓦里安直线加速器上进行照射。
危及器官（OAR）处的平均剂量在同侧肺、对侧肺和心脏分别呈现出34.24%、37.96%和63.47%的统计学显著差异（p<0.001）。放置在同侧乳房皮肤表面界面处的薄膜在四个象限中也分别呈现出16.43%、-10.16%、-14.79%和15.67%的统计学显著差异（p<0.001）。相比之下，代表左侧乳房体积且处于电子平衡范围内的计划靶体积（PTV）剂量仪与TPS之间无显著差异，p = 0.20和p = 0.90。
处于电子平衡状态下的PTV剂量无显著差异；尽管在电子平衡范围之外未达到匹配。
