GPU-based fast Monte Carlo simulation for radiotherapy dose calculation
GPU-based fast Monte Carlo simulation for radiotherapy dose calculation
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DOI：
10.1088/0031-9155/56/22/002
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发表时间：
2011-11-21
影响因子：
3.5
通讯作者：
Jiang, Steve B.
中科院分区：
文献类型：
--
作者：
Jia, Xun;Gu, Xuejun;Jiang, Steve B.
蒙特卡罗（MC）模拟通常被认为是放射治疗中最准确的剂量计算方法。然而，对于许多常规临床应用来说，其效率仍然需要改进。在本文中，我们介绍了基于图形处理单元 (GPU) 的 MC 剂量计算包 gDPM v2.0 的最新开发进展。它利用 GPU 的并行计算能力来实现高效率，同时保持与原始剂量规划方法 (DPM) 代码相同的粒子传输物理原理，从而保持相同水平的模拟精度。在GPU计算中，线程之间执行路径的分歧会大大降低效率。由于光子和电子经历不同的物理过程，因此获得不同的执行路径，因此我们使用光子传输和电子传输分开的模拟方案，以部分缓解线程发散问题。还利用了高性能随机数生成器和硬件线性插值。我们还开发了各种组件来处理注量图和直线加速器几何结构，以便 gDPM 可用于计算实际 IMRT 或 VMAT 治疗计划的剂量分布。我们的 gDPM 包在模型和真实患者病例中都经过了准确性和效率测试。在所有情况下，平均相对不确定性均小于 1%。进行统计t检验，发现CPU和GPU结果之间的剂量差异在96%以上的高剂量区域和97%以上的整个区域中没有统计显着性。使用 NVIDIA Tesla C2050 GPU 卡与 2.27 GHz Intel Xeon CPU 处理器相比，观察到的加速系数为 69.1，与 87.2 相似。对于实际的 IMRT 和 VMAT 计划，使用 gDPM 可以在 36.1 秒（类似于 39.6 秒）内完成 MC 剂量计算，标准偏差小于 1%。
Monte Carlo (MC) simulation is commonly considered to be the most accurate dose calculation method in radiotherapy. However, its efficiency still requires improvement for many routine clinical applications. In this paper, we present our recent progress toward the development of a graphics processing unit (GPU)-based MC dose calculation package, gDPM v2.0. It utilizes the parallel computation ability of a GPU to achieve high efficiency, while maintaining the same particle transport physics as in the original dose planning method (DPM) code and hence the same level of simulation accuracy. In GPU computing, divergence of execution paths between threads can considerably reduce the efficiency. Since photons and electrons undergo different physics and hence attain different execution paths, we use a simulation scheme where photon transport and electron transport are separated to partially relieve the thread divergence issue. A high-performance random number generator and a hardware linear interpolation are also utilized. We have also developed various components to handle the fluence map and linac geometry, so that gDPM can be used to compute dose distributions for realistic IMRT or VMAT treatment plans. Our gDPM package is tested for its accuracy and efficiency in both phantoms and realistic patient cases. In all cases, the average relative uncertainties are less than 1%. A statistical t-test is performed and the dose difference between the CPU and the GPU results is not found to be statistically significant in over 96% of the high dose region and over 97% of the entire region. Speed-up factors of 69.1 similar to 87.2 have been observed using an NVIDIA Tesla C2050 GPU card against a 2.27 GHz Intel Xeon CPU processor. For realistic IMRT and VMAT plans, MC dose calculation can be completed with less than 1% standard deviation in 36.1 similar to 39.6 s using gDPM.