University of South Florida.
J Appl Clin Med Phys. 2014 Mar 6;15(2):4705. doi: 10.1120/jacmp.v15i2.4705.
We report the results of a preclinical evaluation of recently introduced commercial tools for 3D patient IMRT/VMAT dose reconstruction, the Delta4 Anatomy calculation algorithm. Based on the same initial measurement, volumetric dose can be reconstructed in two ways. Three-dimensional dose on the Delta4 phantom can be obtained by renormalizing the planned dose distribution by the measurement values (D4 Interpolation). Alternatively, incident fluence can be approximated from the phantom measurement and used for volumetric dose calculation on an arbitrary (patient) dataset with a pencil beam algorithm (Delta4 PB). The primary basis for comparison was 3D dose obtained by previously validated measurement-guided planned dose perturbation method (ACPDP), based on the ArcCHECK dosimeter with 3DVH software. For five clinical VMAT plans, D4 Interpolation agreed well with ACPDP on a homogeneous cylindrical phantom according to gamma analysis with local dose-error normalization. The average agreement rates were 98.2% ± 1.3% (1 SD), (range 97.0%-100%) and 92.8% ± 3.9% (89.5%-99.2%), for the 3%/3 mm and 2%/2 mm criteria, respectively. On a similar geometric phantom, D4 PB demonstrated substantially lower agreement rates with ACPDP: 88.6% ± 6.8% (81.2%-96.1%) and 72.4% ± 8.4% (62.1%-81.1%), for 3%/3 mm and 2%/2 mm, respectively. The average agreement rates on the heterogeneous patients' CT datasets are lower yet: 81.2% ± 8.6% (70.4%-90.4%) and 64.6% ± 8.4% (56.5%-74.7%), respectively, for the same two criteria sets. For both threshold combinations, matched analysis of variance (ANOVA) multiple comparisons showed statistically significant differences in mean agreement rates (p < 0.05) for D4 Interpolation versus ACPDP on one hand, and D4 PB versus ACPDP on either cylindrical or patient dataset on the other hand. Based on the favorable D4 Interpolation results for VMAT plans, the resolution of the reconstruction method rather than hardware design is likely to be responsible for D4 PB limitations.
我们报告了最近引入的用于 3D 患者 IMRT/VMAT 剂量重建的商业工具 Delta4 Anatomy 计算算法的临床前评估结果。基于相同的初始测量，可以通过两种方式重建体剂量。可以通过将计划剂量分布与测量值进行归一化来获得 Delta4 模体上的三维剂量（D4 插值）。或者，可以从模体测量中近似入射通量，并使用束流算法（Delta4 PB）在任意（患者）数据集上进行体剂量计算。比较的主要依据是以前通过验证的基于 ArcCHECK 剂量计和 3DVH 软件的测量引导计划剂量扰动方法（ACPDP）获得的 3D 剂量。对于五个临床 VMAT 计划，根据局部剂量误差归一化的伽马分析，D4 插值在均匀圆柱形模体上与 ACPDP 吻合良好。对于 3%/3mm 和 2%/2mm 标准，平均符合率分别为 98.2%±1.3%（1SD）（范围 97.0%-100%）和 92.8%±3.9%（89.5%-99.2%）。在类似的几何模体上，D4 PB 与 ACPDP 的符合率显著较低：对于 3%/3mm 和 2%/2mm，分别为 88.6%±6.8%（81.2%-96.1%）和 72.4%±8.4%（62.1%-81.1%）。在不均匀的患者 CT 数据集上，平均符合率更低：对于相同的两个标准集，分别为 81.2%±8.6%（70.4%-90.4%）和 64.6%±8.4%（56.5%-74.7%）。对于两种阈值组合，方差分析（ANOVA）多重比较显示，D4 插值与 ACPDP 之间（一方面）以及 D4 PB 与 ACPDP 之间（另一方面）的平均符合率存在统计学差异（p < 0.05）。基于 VMAT 计划中 D4 插值的良好结果，重建方法的分辨率而不是硬件设计可能是 D4 PB 局限性的原因。
