The spatial resolution of small animal positron emission tomography (PET) scanners can be improved by the use of crystals with fine pitch and rejection of inter-crystal scattering (ICS) events, which leads to a better quantification of radiopharmaceuticals. On the other hand, depth-of-interaction (DOI) information is essential to preserve the spatial resolution at the PET field-of-view (FOV) periphery while keeping the sensitivity. In this study we proposed a novel staggered 3-layer DOI detector using BaSO₄ reflector material for an enhanced crystal identification performance as well as ICS event rejection capability over those of ESR reflector based DOI detectors. The proposed staggered 3-layer DOI detector had 3-layer staggered LYSO crystal arrays (crystal pitch=1 mm), an acrylic light guide, and a 4נ4 SiPM array. The 16 SiPM anode signals were read out by using a resistive network to encode the crystal position and energy information while the timing signal was extracted from the common cathode. The crystal map quality was substantially enhanced by using the BaSO₄ reflector material as compared to that of the ESR reflector due to the low optical crosstalk between the LYSO crystals. The ICS events can be rejected with BaSO₄ by using simple pulse height discrimination thanks to the light collection efficiency difference that depends on the crystal layers. As a result, the total number of events was decreased around 26% with BaSO₄ as compared to that of ESR. The overall energy resolution and coincidence timing resolution with BaSO₄ were 19.75.6% and 591160 ps, respectively which were significantly worse than 10.92.2% and 30823 ps values of ESR because of the relatively low light collection efficiency with BaSO₄ (1057308 ADC) compared to that of ESR (1808118 ADC). In conclusion, we found the proposed staggered 3-layer DOI detector using the BaSO₄ reflector material with ICS event rejection capability can be a cost-effective solution for realizing high resolution and highly sensitive small animal PET scanners while minimizing the complexity of the SiPM readout circuit.

小动物正电子发射断层扫描 (PET) 扫描仪的空间分辨率可以通过使用具有细间距的晶体和抑制晶体间散射 (ICS) 事件来提高，从而更好地量化放射性药物。另一方面，交互深度 (DOI) 信息对于保持 PET 视场 (FOV) 外围的空间分辨率同时保持灵敏度至关重要。_{在这项研究中，我们提出了一种使用 BaSO 4}的新型交错 3 层 DOI 检测器与基于 ESR 反射器的 DOI 探测器相比，反射器材料具有增强的晶体识别性能以及 ICS 事件抑制能力。所提出的交错 3 层 DOI 探测器具有 3 层交错 LYSO 晶体阵列（晶体间距 = 1 mm）、丙烯酸光导和 4נ4 SiPM 阵列。通过使用电阻网络对晶体位置和能量信息进行编码，同时从共阴极提取定时信号，读取 16 个 SiPM 阳极信号。由于 LYSO 晶体之间的低光学串扰，与使用 ESR 反射器相比，使用 BaSO ₄反射器材料显着提高了晶体图质量。可以使用 BaSO _{4拒绝 ICS 事件}由于取决于晶体层的光收集效率差异，通过使用简单的脉冲高度鉴别。结果，与ESR相比，使用BaSO ₄的事件总数减少了约26% 。_{BaSO 4}的总能量分辨率和符合时间分辨率分别为 19.75.6% 和 591160 ps，明显低于 ESR 的 10.92.2% 和 30823 ps 值，因为 BaSO ₄ (1057308 ADC ) 的光收集效率相对较低) 与 ESR (1808118 ADC) 相比。总之，我们使用 BaSO _{4发现了所提出的交错 3 层 DOI 检测器}具有 ICS 事件抑制能力的反射器材料可以成为实现高分辨率和高灵敏度小动物 PET 扫描仪的一种经济高效的解决方案，同时最大限度地降低 SiPM 读出电路的复杂性。