COINCIDENCE TIMING FOR POSITRON IMAGING DEVICES

这项工作的长期目标是获得和测试新的， 特别是对于这种情况， 从正电子湮没中获得的振荡信号 事件 改进的定时测量将减少随机 符合率与较慢的闪烁器，如BGO。 这 这一转变将允许PET仪器的设计能够实现更多功能， 更大剂量的短半衰期药剂的精确成像， 15O或17F。 在快速蒸发器如BaF2的情况下， 改进的定时减少了在定位中的不确定性， 正电子沿着射线沿着湮灭。 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 对于给定数量的检测到的事件进行改进。 基于检测的详细模型的估计理论 系统将用于获得高效、稳健和准确的 光子到达时间的估计。 这些etimates将是 理论上和实验上与传统定时相比， 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 将设计用于大的多信道系统。

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.