Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada. slloyd@bccancer
Med Phys. 2013 Jan;40(1):011707. doi: 10.1118/1.4769419.
Acuros external beam (Acuros XB) is a novel dose calculation algorithm implemented through the ECLIPSE treatment planning system. The algorithm finds a deterministic solution to the linear Boltzmann transport equation, the same equation commonly solved stochastically by Monte Carlo methods. This work is an evaluation of Acuros XB, by comparison with Monte Carlo, for dose calculation applications involving high-density materials. Existing non-Monte Carlo clinical dose calculation algorithms, such as the analytic anisotropic algorithm (AAA), do not accurately model dose perturbations due to increased electron scatter within high-density volumes.
Acuros XB, AAA, and EGSnrc based Monte Carlo are used to calculate dose distributions from 18 MV and 6 MV photon beams delivered to a cubic water phantom containing a rectangular high density (4.0-8.0 g/cm(3)) volume at its center. The algorithms are also used to recalculate a clinical prostate treatment plan involving a unilateral hip prosthesis, originally evaluated using AAA. These results are compared graphically and numerically using gamma-index analysis. Radio-chromic film measurements are presented to augment Monte Carlo and Acuros XB dose perturbation data.
Using a 2% and 1 mm gamma-analysis, between 91.3% and 96.8% of Acuros XB dose voxels containing greater than 50% the normalized dose were in agreement with Monte Carlo data for virtual phantoms involving 18 MV and 6 MV photons, stainless steel and titanium alloy implants and for on-axis and oblique field delivery. A similar gamma-analysis of AAA against Monte Carlo data showed between 80.8% and 87.3% agreement. Comparing Acuros XB and AAA evaluations of a clinical prostate patient plan involving a unilateral hip prosthesis, Acuros XB showed good overall agreement with Monte Carlo while AAA underestimated dose on the upstream medial surface of the prosthesis due to electron scatter from the high-density material. Film measurements support the dose perturbations demonstrated by Monte Carlo and Acuros XB data.
Acuros XB is shown to perform as well as Monte Carlo methods and better than existing clinical algorithms for dose calculations involving high-density volumes.
Acuros 外部射束（Acuros XB）是一种新的剂量计算算法，通过 ECLIPSE 治疗计划系统实现。该算法通过求解线性 Boltzmann 输运方程的确定解，该方程通常由蒙特卡罗方法随机求解。这项工作是对 Acuros XB 的评估，通过与蒙特卡罗方法的比较，评估其在涉及高密度材料的剂量计算应用中的性能。现有的非蒙特卡罗临床剂量计算算法，如解析各向异性算法（AAA），不能准确地模拟由于高密度体积中电子散射增加而导致的剂量扰动。
使用 Acuros XB、AAA 和基于 EGSnrc 的蒙特卡罗方法，计算 18MV 和 6MV 光子束在立方水模体中心包含一个矩形高密度（4.0-8.0g/cm³）体积时的剂量分布。还使用这些算法重新计算涉及单侧髋关节假体的临床前列腺治疗计划，该计划最初使用 AAA 进行评估。使用伽马指数分析对这些结果进行图形和数值比较。放射性染色胶片测量结果补充了蒙特卡罗和 Acuros XB 剂量扰动数据。
使用 2%和 1mm 伽马分析，对于涉及 18MV 和 6MV 光子、不锈钢和钛合金植入物以及轴上和斜角照射的虚拟体模，Acuros XB 中超过 50%归一化剂量的剂量体素中，有 91.3%到 96.8%与蒙特卡罗数据一致。AAA 与蒙特卡罗数据的伽马分析显示，有 80.8%到 87.3%的一致性。将 Acuros XB 和 AAA 对涉及单侧髋关节假体的临床前列腺患者计划的评估进行比较，Acuros XB 与蒙特卡罗结果吻合较好，而 AAA 由于高密度材料的电子散射，低估了假体上游内侧表面的剂量。胶片测量结果支持蒙特卡罗和 Acuros XB 数据所显示的剂量扰动。
Acuros XB 被证明在涉及高密度体积的剂量计算中与蒙特卡罗方法表现相当，优于现有的临床算法。
