DEPTH OF INTERACTION MEASUREMENT IN ANGER CAMERAS

几家商业公司最近推出了双头Anger相机系统，能够同时进行重合光子和单光子成像。这些系统有可能成为许多社区医院专用正电子发射断层扫描（PET）系统的替代品。然而，这些系统的符合成像性能，在系统灵敏度和空间分辨率方面，目前福尔斯明显低于专用的最先进的PET系统。为了提高符合成像的总体检测效率，厚的NaI（Tl）晶体被用于这些多用途系统中。不幸的是，当双Anger相机系统在符合成像模式下操作时，厚晶体增强视差误差，这降低了重建图像分辨率;厚晶体还降低了固有空间分辨率性能，特别是当对低能量单光子示踪剂成像时。视差误差的影响可以最小化，如果探测到的伽马射线的相互作用的深度（DOI）进行测量。此外，我们相信相同的DOI信息可以用于提高固有的空间分辨率。我们建议研究一种方法的可行性，使用波长移动（WLS）的偏振光纤，耦合在一个线性阵列的大面积NaI（Tl）晶体的入射面，测量在愤怒相机的DOI。我们假设，由闪烁光纤测量的光输出分布随DOI而变化：随着相互作用的位点远离入射面移动，分布的宽度变宽。在这项研究中，我们将开发必要的硬件和软件进行DOI测量与WLS衍射光纤，特别是厚的大面积NaI（Tl）晶体，如商业多用途双头Anger相机系统中使用的。我们将评估我们的方法，以减少符合成像的视差误差的能力。我们还将研究衍生的DOI信息在3-D线性校正技术中的潜在用途，以提高Anger相机的平面固有空间分辨率。

Several commercial companies have recently introduced dual-head Anger camera systems capable of both coincidence-photon and single-photon imaging. These systems may have the potential to be an alternative to dedicated positron emission tomography (PET) systems for many community hospitals. However, the coincidence-imaging performance of these systems, in terms of system sensitivity and spatial resolution, currently falls significantly short of that of dedicated state-of-the-art PET systems. To increase the overall detection efficiency for coincidence imaging, thick NaI(Tl) crystals are being used in these multi-purpose systems. Unfortunately, thick crystals enhance parallax errors that degrade reconstructed image resolution when the dual-Anger camera system is operated in coincidence-imaging mode; thick crystals also degrade intrinsic spatial resolution performance, particularly when imaging low- energy single-photon tracers. The effects of parallax errors can be minimized if the depth of interaction (DOI) of detected gamma rays is measured. In addition we believe the same DOI information could be used to improve intrinsic spatial resolution. We propose to study the feasibility of a method to use wavelength-shifting (WLS) scintillating optical fibers, coupled in a linear array to the entrance face of a large-area NaI(Tl) crystal, to measure DOI in Anger cameras. We hypothesize that the light output distribution measured by the scintillation fibers varies with DOI: the width of the distribution broadens as the site of interaction moves farther from the entrance face. In this research, we will develop the hardware and software necessary for performing DOI measurement with WLS scintillating fibers, particularly for thick large- area NaI(Tl) crystals like those used in commercial multi-purpose dual- head Anger camera systems. We will evaluate the ability of our approach to reduce parallax errors in coincidence imaging. We also will investigate the potential use of the derived DOI information in 3-D linearity correction techniques to the improve planar intrinsic spatial resolution of Anger cameras.