Conceptual design of next generation PET and improvement on quantity of PET images

同时具有高灵敏度和高空间分辨率的下一代PET的概念设计已经完成。消除视差而不降低灵敏度的方法是使用测量入射伽马射线的相互作用深度（DOI）的探测器模块。使用深度编码方案的检测器单元被设计和构造用于试验。该装置由4块Gd_2SiO_5：Ce（GSO）晶体组成2 × 2阵列，耦合到具有金属通道倍增电极和4 × 4多阳极的位置敏感光电倍增管（PS-PMT）。我们提出的探测器应该是一个非常可靠和简单的解决方案，适用于体积PET设备，因为所提出的深度编码方案是用所有相同的晶体元件构造的，不需要额外的光电探测器，也不需要不同类型的放大器的组合。我们已经估计了下一代PET扫描仪的计数率属性的基础上的GSO探测器的DOI能力，使用大面积的PS-PMT。建议的探测器单元由64个晶体块与4个阶段的2x2 GSO阵列耦合到一个52平方毫米的PS-PMT，具有小死空间。通过晶体块中的适当光控制，可以使用简单的Anger型定位逻辑来获得DOI信息。因此，可以使用具有标准采集架构的计数率模型来计算死区时间因子。用蒙特卡罗模拟程序跟踪了闪烁体和均匀圆柱体中的康普顿相互作用和光电相互作用。初步结果表明，与目前的PET扫描仪相比，尽管探测器模块的尺寸相对较大，但所提出的扫描仪设计可以获得高噪声等效计数率。计数率性能可以通过减少导致块死区时间损失的单个事件来提高，但代价是灵敏度略有下降。

Conceptual design of the next generation PET with both high sensitivity and high spatial resolution has been performed. The method for eliminating the parallax error without reducing sensitivity is to use the detector module that measures the depth of interaction (DOI) of incident gamma rays. A detector unit using a depth encoding scheme was designed and constructed for trial. The unit consists of four Gd_2SiO_5:Ce(GSO) crystal blocks in a 2x2 array coupled to a position-sensitive photomultiplier tube (PS-PMT) having metal channel dynodes and 4x4 multi-anodes. Our proposed detector should be a very reliable and simple solution suitable for volume PET devices since the proposed depth encoding scheme is constructed with all the same crystal elements and does not need additional photo-detectors nor a combination of different types of scintillators. We have estimated count rate properties of the next generation PET scanners based on the GSO detector with DOI capability using a large area PS-PMT. The proposed detector unit consists of 64 crystal blocks with four stages of 2x2 GSO arrays coupled to a 52 mm square PS-PMT which has small dead space. With appropriate light control in the crystal block, DOI information can be obtained using simple Anger-type positioning logic. Thus dead time factors can be calculated using a count rate model with standard acquisition architecture. Compton and photoelectric interactions in the scintillator and uniform cylindrical phantoms were tracked by Monte Carlo simulation programs. The preliminary results suggest that, compared to current PET scanners, high noise equivalent count rate can be obtained by the proposed scanner designs despite the relatively large size of the detector module. The count rate performance can be improved by the reduction of single events that cause block dead time losses at the cost of a slight decrease in sensitivity.