Université de Lyon, CREATIS, CNRS UMR5220; Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, France.
Phys Med Biol. 2018 Mar 2;63(5):055011. doi: 10.1088/1361-6560/aa9e32.
Monte-Carlo simulations of SPECT images are notoriously slow to converge due to the large ratio between the number of photons emitted and detected in the collimator. This work proposes a method to accelerate the simulations based on fixed forced detection (FFD) combined with an analytical response of the detector. FFD is based on a Monte-Carlo simulation but forces the detection of a photon in each detector pixel weighted by the probability of emission (or scattering) and transmission to this pixel. The method was evaluated with numerical phantoms and on patient images. We obtained differences with analog Monte Carlo lower than the statistical uncertainty. The overall computing time gain can reach up to five orders of magnitude. Source code and examples are available in the Gate V8.0 release.
由于在准直器中发射和探测的光子数量之间存在很大的比例，因此 SPECT 图像的蒙特卡罗模拟收敛速度非常慢。这项工作提出了一种基于固定强制检测（FFD）与探测器的分析响应相结合的方法来加速模拟。FFD 基于蒙特卡罗模拟，但在每个探测器像素中强制检测光子，其权重由发射（或散射）和传输到该像素的概率决定。该方法使用数值体模和患者图像进行了评估。我们得到的与模拟蒙特卡罗的差异低于统计不确定性。总的计算时间增益可以达到五个数量级。源代码和示例可在 Gate V8.0 版本中获得。
