Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW, 2234, Australia.
Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.
Phys Med Biol. 2020 Dec 18;65(23):235051. doi: 10.1088/1361-6560/abaa24.
The purpose of this work is to develop a validated Geant4 simulation model of a whole-body prototype PET scanner constructed from the four-layer depth-of-interaction detectors developed at the National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan. The simulation model emulates the behaviour of the unique depth of interaction sensing capability of the scanner without needing to directly simulate optical photon transport in the scintillator and photodetector modules. The model was validated by evaluating and comparing performance metrics from the NEMA NU 2-2012 protocol on both the simulated and physical scanner, including spatial resolution, sensitivity, scatter fraction, noise equivalent count rates and image quality. The results show that the average sensitivities of the scanner in the field-of-view were 5.9 cps kBq and 6.0 cps kBq for experiment and simulation, respectively. The average spatial resolutions measured for point sources placed at several radial offsets were 5.2± 0.7 mm and 5.0± 0.8 mm FWHM for experiment and simulation, respectively. The peak NECR was 22.9 kcps at 7.4 kBq ml for the experiment, while the NECR obtained via simulation was 23.3 kcps at the same activity. The scatter fractions were 44% and 41.3% for the experiment and simulation, respectively. Contrast recovery estimates performed in different regions of a simulated image quality phantom matched the experimental results with an average error of -8.7% and +3.4% for hot and cold lesions, respectively. The results demonstrate that the developed Geant4 model reliably reproduces the key NEMA NU 2-2012 performance metrics evaluated on the prototype PET scanner. A simplified version of the model is included as an advanced example in Geant4 version 10.5.
这项工作的目的是开发一个经过验证的 Geant4 模拟模型，该模型由日本国立放射研究所、量子和放射科学研究所开发的四层深度交互探测器构建而成，用于整个身体原型 PET 扫描仪。该模拟模型模拟了扫描仪独特的深度交互感应能力，而无需直接模拟闪烁体和光电探测器模块中的光学光子传输。该模型通过评估和比较 NEMA NU 2-2012 协议中的性能指标在物理扫描仪和模拟扫描仪上进行了验证，包括空间分辨率、灵敏度、散射分数、噪声等效计数率和图像质量。结果表明，在视场中，扫描仪的平均灵敏度分别为实验和模拟的 5.9 cps kBq 和 6.0 cps kBq。在几个径向偏移处放置点源时测量的平均空间分辨率分别为实验和模拟的 5.2±0.7mm 和 5.0±0.8mm FWHM。实验中，峰值 NECR 在 7.4 kBq ml 时为 22.9 kcps，而通过模拟获得的 NECR 在相同活度时为 23.3 kcps。散射分数分别为实验和模拟的 44%和 41.3%。在模拟图像质量体模的不同区域进行的对比恢复估计与实验结果匹配，热和冷病变的平均误差分别为-8.7%和+3.4%。结果表明，开发的 Geant4 模型可靠地再现了原型 PET 扫描仪上评估的关键 NEMA NU 2-2012 性能指标。该模型的简化版本作为 Geant4 版本 10.5 中的高级示例包含在内。
