Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia; Faculty of Electronic and Computer Engineering, Universiti Teknikal Malaysia Melaka (UTeM), 76100 Durian Tunggal, Melaka, Malaysia.
Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
Appl Radiat Isot. 2022 Nov;189:110418. doi: 10.1016/j.apradiso.2022.110418. Epub 2022 Aug 23.
Monte Carlo N-Particle (MCNP) simulation has been extensively proven in nuclear medicine imaging systems, most notably in designing and optimizing new medical imaging tools. It enables more complicated geometries and the simulation of particles passing through and interacting with materials. However, a relatively long simulation time is a drawback of Monte Carlo simulation, mainly when complex geometry exists. The current study presents an alternative variance reduction technique for a modeled positron emission tomography (PET) camera by reducing the height of the source volume definition while maintaining the geometry of the simulated model. The National Electrical Manufacturers Association (NEMA) of the International Electrotechnical Commission (IEC) PET's phantom was used with a 1 cm diameter and 7 cm height of line source placed in the middle. The first geometry was fully filled the line source with 0.50 mCi radioactivity. In contrast, the second geometry decreased the source definition to 2.4 cm in height, covering 1 cm above and below the sub-block detector level. The source volume definition approach led to a 71% reduction in the total photons to be simulated. Results showed that the proposed variance reduction strategy could produce spatial resolution as precise as fully filled geometry and sped up the simulation time by approximately 65%. Hence, this strategy can be utilized for further PET optimizing simulation studies.
蒙特卡罗粒子（MCNP）模拟在核医学成像系统中得到了广泛的证明，尤其是在设计和优化新的医学成像工具方面。它可以模拟更复杂的几何形状和粒子穿过并与材料相互作用的过程。然而，蒙特卡罗模拟的一个缺点是相对较长的模拟时间，特别是在存在复杂几何形状的情况下。本研究提出了一种替代的正电子发射断层成像（PET）相机的方差减少技术，通过在保持模拟模型的几何形状的同时减少源体积定义的高度来实现。使用美国国家电器制造商协会（NEMA）国际电工委员会（IEC）的 PET 体模，在中间位置放置一个直径为 1 厘米、高为 7 厘米的线源。第一个几何形状完全填充了 0.50 毫居里放射性的线源。相比之下，第二个几何形状将源定义减少到 2.4 厘米高，覆盖子块探测器水平以上和以下各 1 厘米。源体积定义方法导致要模拟的总光子数减少了 71%。结果表明，所提出的方差减少策略可以产生与完全填充几何形状一样精确的空间分辨率，并将模拟时间缩短约 65%。因此，该策略可用于进一步的 PET 优化模拟研究。
