POSITION-SENSITIVE APD DETECTORS FOR SMALL ANIMAL PET

描述(申请人提供)：小型动物PET扫描仪尚未达到可达到的最高灵敏度和空间分辨率，这主要是由于大多数探测器设计中在空间分辨率和效率之间进行了不利的权衡。该方案的目标是开发基于位置敏感雪崩光电二极管(PSAPD)技术的用于活体PET分子成像的高分辨率、高灵敏度深度编码探测器，并基于PSAPD/LSO探测器模块开发用于小动物成像的高空间分辨率和高分辨率均匀度扫描仪。PSAPD提供了几个吸引人的特征，包括低密度读出(事件位置仅在四个信号输出中编码)、薄截面(能够双端读出闪烁体阵列以提供相互作用深度信息)和高量子效率。初步数据清楚地表明，这些设备能够分辨1x1 mm横截面的LSO晶体阵列，并利用20 mm厚的探测器提供3-4 mm深度的相互作用分辨率。该方案的研究旨在开发和优化适合于高分辨率、高灵敏度小动物PET扫描仪的PSAPD探测器。具体地说，实验将研究最小可分辨LSO晶体尺寸作为PSAPD表面积和温度的函数、不同PSAPD读出方案的影响、相互作用分辨率作为晶体长度、尺寸和表面处理的函数以及PSAPD作为时间、偏置电压和温度的函数的稳定性。对PSAPD/LSO PET探测器的全面评估将包括洪水直方图、单个晶体能谱、相互作用深度分辨率、时间分辨率和固有空间分辨率的测量。将与基于位置灵敏光电倍增管的LSO探测器进行定量比较。(目前在大多数小动物PET系统中使用的技术)。最后，将利用优化后的PSAPD/LSO探测器作为概念验证，开发一台简单的单探测器环小动物PET扫描仪。将为具有深度交互能力的PET系统开发电子学、数据采集和图像重建算法。基于这些结果，将预测由这些探测器模块构建的多环小动物PET系统的性能(在空间分辨率和灵敏度方面)，并与现有的商用小动物PET扫描仪进行比较。

DESCRIPTION (provided by applicant): Small-animal PET scanners have not reached the highest sensitivity and spatial resolution that is achievable, largely due to an unfavorable trade-off between spatial resolution and efficiency in most detector designs. The objective of this proposal is to develop high resolution, high sensitivity depth-encoding detectors for in vivo molecular imaging with PET based on position-sensitive avalanche photodiode (PSAPD) technology and develop a high spatial resolution and high resolution uniformity prototype scanner for small-animal imaging based on PSAPD/LSO detector modules. PSAPDs offer several attractive features including low density readout (event location is encoded in just four signal outputs), thin cross-section (enabling dual- ended read out of scintillator arrays to provide depth of interaction information) and high quantum efficiency. Preliminary data has clearly demonstrated the ability of these devices to resolve arrays of 1x1 mm cross- section LSO crystals and to provide a 3-4 mm depth of interaction resolution with 20 mm thick detectors. The research in this proposal seeks to develop and optimize PSAPD detectors suitable for incorporation into a high resolution, high sensitivity small-animal PET scanner. Specifically, experiments will address the minimum resolvable LSO crystal size as a function of PSAPD surface area and temperature, the effect of different PSAPD read out schemes, depth of interaction resolution as a function of crystal length, size, and surface treatment, and the stability of PSAPD as a function of time, bias voltage and temperature. A complete evaluation of PSAPD/LSO PET detectors will include measurements of flood histograms, individual crystal energy spectra, depth of interaction resolution, timing resolution and intrinsic spatial resolution. Quantitative comparison will be made to LSO detectors based on position sensitive photomultiplier tubes . (the technology currently used in most small-animal PET systems). Finally a simple single detector ring small-animal PET scanner will be developed using the optimized PSAPD/LSO detectors as a proof of concept. Electronics, data acquisition and image reconstruction algorithms will be developed for the PET system with depth of interaction capability. Based on these results, the performance (in terms of spatial resolution and sensitivity) of a multi-ring small-animal PET system built from these detector modules will be predicted and compared with available commercial small-animal PET scanners.