Evaluation of organ-specific peripheral doses after 2-dimensional, 3-dimensional and hybrid intensity modulated radiation therapy for breast cancer based on Monte Carlo and convolution/superposition algorithms: Implications for secondary cancer risk assessment
Evaluation of organ-specific peripheral doses after 2-dimensional, 3-dimensional and hybrid intensity modulated radiation therapy for breast cancer based on Monte Carlo and convolution/superposition algorithms: Implications for secondary cancer risk assessment
复制标题
DOI：
10.1016/j.radonc.2012.11.012
复制
发表时间：
2013-01-01
影响因子：
5.7
通讯作者：
Moeckli, Raphael
中科院分区：
文献类型：
--
作者：
Joosten, Andreas;Matzinger, Oscar;Moeckli, Raphael
背景与目的：利用蒙特卡罗（MC）模拟对不同乳腺癌照射技术的器官特异性场外剂量进行综合评价，并与商业治疗计划系统（TPS）的结果进行比较。材料与方法：比较3种使用6MV切向光子束的乳房放疗技术：(a) 2DRT（开放矩形场），(b) 3DCRT（共形楔形场），(c)混合IMRT（开放共形+调制场）。在全身CT扫描中勾画了超过35个器官的轮廓，并通过MC和TPS确定了器官特异性剂量分布。结果：MC和TPS计算的场外剂量存在较大差异，即使对于接近目标体积的器官，如心脏、肺和对侧乳房，差异也高达70%。MC模拟表明，场外剂量的很大一部分来自场外头部散射通量（bbb40 %），而TPS没有充分模拟。基于MC模拟，使用外部楔形的3DCRT技术产生的剂量明显高于2DRT和混合IMRT技术，后者产生相似的场外剂量（在骨盆中高达4-5倍）。结论：与普遍看法形成鲜明对比的是，与传统技术相比，本文研究的IMRT技术不会增加场外剂量，可能提供最理想的方案。带有外部楔形的3D-CRT技术产生最大的场外剂量。为了准确地评估场外剂量，不应使用商业TPS，即使是靠近目标体积的器官（对侧乳房、肺、心脏）。2012爱思唯尔爱尔兰有限公司版权所有。放射治疗与肿瘤杂志，2013,33-41
Background and purpose: To make a comprehensive evaluation of organ-specific out-of-field doses using Monte Carlo (MC) simulations for different breast cancer irradiation techniques and to compare results with a commercial treatment planning system (TPS).Materials and methods: Three breast radiotherapy techniques using 6MV tangential photon beams were compared: (a) 2DRT (open rectangular fields), (b) 3DCRT (conformal wedged fields), and (c) hybrid IMRT (open conformal + modulated fields). Over 35 organs were contoured in a whole-body CT scan and organ-specific dose distributions were determined with MC and the TPS.Results: Large differences in out-of-field doses were observed between MC and TPS calculations, even for organs close to the target volume such as the heart, the lungs and the contralateral breast (up to 70% difference). MC simulations showed that a large fraction of the out-of-field dose comes from the out-of-field head scatter fluence (>40%) which is not adequately modeled by the TPS. Based on MC simulations, the 3DCRT technique using external wedges yielded significantly higher doses (up to a factor 4-5 in the pelvis) than the 2DRT and the hybrid IMRT techniques which yielded similar out-of-field doses.Conclusions: In sharp contrast to popular belief, the IMRT technique investigated here does not increase the out-of-field dose compared to conventional techniques and may offer the most optimal plan. The 3D-CRT technique with external wedges yields the largest out-of-field doses. For accurate out-of-field dose assessment, a commercial TPS should not be used, even for organs near the target volume (contralateral breast, lungs, heart). (C) 2012 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 106 (2013) 33-41