Validation of a new grid-based Boltzmann equation solver for dose calculation in radiotherapy with photon beams
Validation of a new grid-based Boltzmann equation solver for dose calculation in radiotherapy with photon beams
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DOI：
10.1088/0031-9155/55/3/002
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发表时间：
2010-02-01
影响因子：
3.5
通讯作者：
Mourtada, Firas
中科院分区：
文献类型：
--
作者：
Vassiliev, Oleg N.;Wareing, Todd A.;Mourtada, Firas
一种新的基于网格的玻尔兹曼方程求解器，Acuros（TM），专门用于执行准确和快速的放射治疗剂量计算。在这项研究中，我们基准其性能对蒙特卡罗6和18 MV光子束在异质介质。Acuros解决了耦合玻尔兹曼输运方程的中性和带电粒子的局部自适应笛卡尔网格。Acuros求解器是通用Attila（c）软件的优化重写，对于可比的精度水平，它大约比Attila快一个数量级。蒙特卡罗（EGSnrc）和Acuros之间的比较6和18 MV光子束撞击板体模，包括组织，骨和肺材料。为了提供准确的参考解决方案，蒙特卡洛模拟运行到严格的统计不确定性（σ近似为0.1%）和精细分辨率（1-2 mm）。Acuros结果在包含整个体模的2 mm立方体素网格上输出。还对拟人化体模上的乳房治疗计划进行了比较。对于剂量超过最大剂量10%的区域的板体模，Acuros和Monte Carlo之间的一致性在局部剂量的2%以内或距离一致1 mm的范围内。对于乳腺病例，在剂量超过处方剂量10%的情况下，99.9%的体素的一致性在局部剂量的2%或2 mm距离内。在其他地方，在低剂量区域，所有病例的一致性均在最大剂量的1%范围内。由于所有Acuros计算在双核双处理器工作站上需要不到5分钟，因此对于常规临床使用来说足够高效。此外，由于Acuros计算时间仅微弱地依赖于射束的数量，因此Acuros可以理想地适用于弧形治疗，其中当前的临床算法可能导致长的计算时间。
A new grid-based Boltzmann equation solver, Acuros (TM), was developed specifically for performing accurate and rapid radiotherapy dose calculations. In this study we benchmarked its performance against Monte Carlo for 6 and 18 MV photon beams in heterogeneous media. Acuros solves the coupled Boltzmann transport equations for neutral and charged particles on a locally adaptive Cartesian grid. The Acuros solver is an optimized rewrite of the general purpose Attila (c) software, and for comparable accuracy levels, it is roughly an order of magnitude faster than Attila. Comparisons were made between Monte Carlo (EGSnrc) and Acuros for 6 and 18 MV photon beams impinging on a slab phantom comprising tissue, bone and lung materials. To provide an accurate reference solution, Monte Carlo simulations were run to a tight statistical uncertainty (sigma approximate to 0.1%) and fine resolution (1-2 mm). Acuros results were output on a 2 mm cubic voxel grid encompassing the entire phantom. Comparisons were also made for a breast treatment plan on an anthropomorphic phantom. For the slab phantom in regions where the dose exceeded 10% of the maximum dose, agreement between Acuros and Monte Carlo was within 2% of the local dose or 1 mm distance to agreement. For the breast case, agreement was within 2% of local dose or 2 mm distance to agreement in 99.9% of voxels where the dose exceeded 10% of the prescription dose. Elsewhere, in low dose regions, agreement for all cases was within 1% of the maximum dose. Since all Acuros calculations required less than 5 min on a dual-core two-processor workstation, it is efficient enough for routine clinical use. Additionally, since Acuros calculation times are only weakly dependent on the number of beams, Acuros may ideally be suited to arc therapies, where current clinical algorithms may incur long calculation times.