MCGPU-PET: An open-source real-time Monte Carlo PET simulator

Monte Carlo (MC) simulations are commonly used to model the emission, transmission, and/or detection of radiation in Positron Emission Tomography (PET). In this work, we introduce a new open-source MC software for PET simulation, MCGPU-PET, which has been designed to fully exploit the computing capabilities of modern GPUs to simulate the acquisition of more than 100 million coincidences per second from voxelized sources and material distributions. The new simulator is an extension of the PENELOPE-based MCGPU code previously used in cone-beam CT and mammography applications. We validated the accuracy of the accelerated code by comparing it to GATE and PeneloPET simulations achieving an agreement within 10 percent approximately. As an example application of the code for fast estimation of PET coincidences, a scan of the NEMA IQ phantom was simulated. A fully 3D sinogram with 6382 million true coincidences and 731 million scatter coincidences was generated in 54 s in one GPU. MCGPU-PET provides an estimation of true and scatter coincidences and spurious background (for positron-gamma emitters such as 124I) at a rate 3 orders of magnitude faster than CPU-based MC simulators. This significant speed-up enables the use of the code for accurate scatter and prompt-gamma background estimations within an iterative image reconstruction process.

蒙特卡洛（MC）模拟在正电子发射断层扫描（PET）中广泛用于模拟辐射的发射、传输以及或检测。在本研究中，我们引入了一种新的开源蒙特卡洛模拟软件MCGPU-PET，该软件旨在充分利用现代GPU的计算能力，以模拟从体素化源和材料分布中每秒获取超过一亿个符合事件。新的模拟器是PENELOPE为基础的MCGPU代码的扩展，之前已在锥束CT和乳腺摄影应用中使用。通过将加速代码与GATE和PeneloPET模拟进行比较，验证了其准确性，两者之间的一致性约为10%。作为该代码用于快速估计PET符合事件的应用示例，对NEMA IQ体模进行了模拟。在一个GPU中，生成了一个包含63.82亿个真实符合事件和7.31亿个散射符合事件的完整3D sinogram，耗时54秒。MCGPU-PET提供了对真实和散射符合事件以及伪背景（例如124I的正电子-伽马发射体）的估计，其速度比基于CPU的蒙特卡洛模拟器快三个数量级。这种显著的速度提升使得代码能够用于迭代图像重建过程中的准确散射和prompt-伽马背景估计。