In this work, a Monte Carlo simulation of a positron emission mammography (PEM) prototype under development at the Institute of Physics, UNAM, is presented. The simulated geometry included two parallel detector modules with a 73 mm separation. Each module consisted of 3 detector blocks, each one formed by an array of 38×38 lutetium yttrium orthosilicate crystal elements of 1.96×1.96×10 mm~3 at 2 mm pitch. An energy resolution of 26% for 511 keV photons, a 350-650 keV energy window and a 6 ns coincidence window were assumed. Image reconstruction was performed using focal plane tomography. Spatial resolution was assessed through the point spread function at different positions within the field of view (FOV). In addition, image quality was evaluated following the NEMA NU 4-2008 protocol. Different depth-of-interaction (DOI) assumptions were considered. The best spatial resolution (0.75 mm FWHM) was obtained when depth-of-interaction information was used, deteriorating drastically to 2.21 mm when DOI is unknown. The overall sensitivity of the system was 2.50%.
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机译：在这项工作中，介绍了在物理研究所开发的正电子发射乳房X线摄影（PEM）原型的Monte Carlo仿真。模拟几何形状包括两个平行检测器模块，分离为73mm。每个模块由3个探测器块组成，每个模块由38×38乳酸钇的阵列形成1.96×1.96×10mm〜3的阵列，2mm间距。假设511 keV光子的能量分辨率为26％，350-650kev能量窗口和6ns重合窗口。使用焦平面断层扫描进行图像重建。通过在视野（FOV）内的不同位置的点传播功能来评估空间分辨率。此外，在NEMA NU 4-2008协议下评估图像质量。考虑了不同的相互作用（DOI）假设。当使用深度信息时，获得最佳空间分辨率（0.75mm FWHM），当DOI未知时，在2.21毫米的情况下恶化。该系统的整体敏感性为2.50％。
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