COINCIDENCE TIMING FOR POSITRON IMAGING DEVICES

这项工作的长期目标是派生和测试新的、 改进了重合时间的方法，特别是在 正电子湮没获得的闪烁信号 事件。改进的定时测量将减少随机性 与较慢的闪烁体(如BGO)的符合率。此入站 TURN将允许设计具有更多功能的PET仪器 较大剂量的短半衰期制剂的准确成像，如 15度或17度。在诸如BaF2的快闪烁体的情况下， 改进的定时减少了位置的不确定性 沿着射线的正电子湮没。这相当于 提高飞行时间正电子断层扫描的灵敏度 由于重建图像中的信噪比是 针对给定数量的检测到的事件进行了改进。 基于详细的检测模型的估计理论 系统将用于派生高效、健壮和准确的 光子到达时间的估计。这些评估数据将是 从理论和实验上与传统计时进行了比较 使用前沿和恒定分数触发器的方法。 最后，实现这些估计器的实验方法 对于一个大型的多通道系统将被设计出来。

The long term goal of this work is to derive and test new, improved approaches to coincidnc timing especially for the case of scinitillation signals obtained from positron annihiliation events. Improved timing measurement will reduce the random coincidence rate with slower scintillators such as BGO. This in turn will permit design of PET instruments capable of more accurate imaging of larger doses of short half-life agents such as 15O or 17F. In the case of fast scintillators such as BaF2, improved timing reduces the uncertainty in the location of the positron annihilation along the ray. This is equivalent to increasing the sensitivity of a Time-of-Flight positron tomography since the signal-to-noise ratio in the reconstructed image is improved for a given number of detected events. Estimation theory based o a detailed model of the detection system will be used to derive efficient, robust, and accurate estimates of the photon arrival time. These etimates will be theoretically and experimentally compared to conventional timing methods which use leading edge and constant fraction triggers. Finally, experimental methods for implementing these estimators for a large multi-channel system will be devised.