Matsuoka Takanori, Araki Fujio, Ohno Takeshi, Sakata Junichi, Tominaga Hirofumi
Graduate School of Health Sciences, Kumamoto University, Kumamoto, Japan.
Department of Health Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
Med Dosim. 2019;44(3):284-290. doi: 10.1016/j.meddos.2018.10.004. Epub 2018 Nov 16.
The purpose of this study was to investigate the dependence of volume dose indices on dose calculation algorithms for volumetric modulated arc therapy (VMAT) for stereotactic body radiotherapy (SBRT) plans to treat peripheral lung tumors by comparing them with those of Monte Carlo (MC) calculations. VMAT-SBRT plans for peripheral lung tumors were created using the Eclipse treatment planning system (TPS) for 24 patients with nonsmall cell lung cancer. VMAT dose distributions for gross tumor volume (GTV), internal target volume (ITV), and planning target volume (PTV) were calculated using the analytical anisotropic algorithm (AAA), the Acuros XB (AXB) algorithm, and a MC algorithm. VMAT dose distributions of the 3 algorithms were compared using their volume dose indices from dose volume histograms (DVHs), a dose difference map, and 3-dimensional gamma analysis. The DVHs for GTV and ITV from AAA, AXB, and MC were in good agreement. The difference between the ITV and PTV volume dose indices from AAA and MC increased as D, D, D, D, and D. In particular, the difference between D for PTV from AAA and MC was up to 48%. A >5% difference between D for PTV from AAA and MC was 11 patients, but only 2 patients for ITV. The volume dose indices for AXB were near those of MC. AAA tended to overestimate the PTV volume dose indices compared to AXB and MC. Thus, we propose that the volume dose indices for the ITV be used because they are independent of dose calculation algorithms.
本研究的目的是通过将立体定向体部放疗（SBRT）计划中容积调强弧形治疗（VMAT）的容积剂量指数与蒙特卡罗（MC）计算结果进行比较，来研究其对剂量计算算法的依赖性，这些计划用于治疗周围型肺肿瘤。使用Eclipse治疗计划系统（TPS）为24例非小细胞肺癌患者创建了周围型肺肿瘤的VMAT-SBRT计划。使用分析各向异性算法（AAA）、Acuros XB（AXB）算法和MC算法计算大体肿瘤体积（GTV）、内部靶区体积（ITV）和计划靶区体积（PTV）的VMAT剂量分布。使用剂量体积直方图（DVH）中的容积剂量指数、剂量差异图和三维伽马分析对这三种算法的VMAT剂量分布进行比较。AAA、AXB和MC的GTV和ITV的DVH结果吻合良好。AAA和MC的ITV与PTV容积剂量指数之间的差异随着D、D、D、D和D而增加。特别是，AAA和MC的PTV的D之间的差异高达48%。AAA和MC的PTV的D之间差异>5%的有11例患者，但ITV只有2例。AXB的容积剂量指数接近MC的。与AXB和MC相比，AAA往往高估PTV容积剂量指数。因此，我们建议使用ITV的容积剂量指数，因为它们与剂量计算算法无关。
