Ultra-dense and Fast Ceramic Scintillator for PET

用于 PET 的超致密快速陶瓷闪烁体

• 批准号: 10413270
• 负责人: JAROSLAW GLODO
• 金额: $ 65.17万
• 依托单位: RADIATION MONITORING DEVICES, INC.
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10413270
• 关键词: Ultra; dense; Fast; Ceramic; Scintillator

Project Summary The current detector technology in PET requires scintillation that has fast response, excellent timing resolution, high detection sensitivity, good energy resolution, and last but not least acceptable cost. At present, most PET systems use crystals of LSO (Lu2SiO5:Ce) or its analog LYSO, which satisfy many of the listed requirements. But LSO, after years of development, has reached its performance limit, especially for the scanners with a long axial field of view (AFOV) that are currently being developed. The goal of these scanners is to increase the geometrical coverage and significantly increase detection sensitivity (by a factor of 30-40), thereby reducing the scanning times (30-40 times faster) or the patient's radiation exposure. However, long AFOV scanners face two main challenges: greater depth-of-interaction (DOI) effects, which increase blurring and noise; and an increase in the volume required for the constituent crystals, which make up some 50% of the cost of the entire scanner. The use of shorter crystals can counteract both the DOI effects and the increased crystal volume (hence cost), but with a major loss of detection efficiency, defeating the original purpose. Another approach for reducing DOI effects is a double-ended read-out but this increases both cost and system complexity. Therefore, to achieve viable and affordable long AFOV scanners, a new scintillation material is required that would provide higher stopping power than LSO, with similar or better timing properties, and at a lower cost. These requirements can be met by a scintillator based on Lu2O3. This host has a very high density (9.4 g/cm3 vs. 7.4 g/cm3 for LSO) and an effective Z of 68 vs. 65. When doped with Yb3+, it exhibits an ultra-fast charge transfer (CT) luminescence with decay time on the order of 1 ns, substantially faster than the 40 ns of LSO. While the material's light yield is low, its timing properties are excellent with better than 250 ps resolution FWHM when paired with LaBr3:Ce. The only property where the material is deficient is its energy resolution (>15% at 511 keV, due to its low light yield). Fortunately, this shortcoming can be addressed by double doping, which increases its light yield to about 20,000 ph/MeV. In this project, we plan to optimize the doping content of Lu2O3 so as to maximize its scintillation properties and achieve energy resolution of about 8% at 511 keV and timing resolution of 200 ps. In Phase II we will increase the volumes of produced material, develop cost reduction schemes, and produce and evaluate PET detection modules with the same performance goals.

项目概要 当前 PET 检测器技术要求闪烁响应速度快、性能优良 定时分辨率、高检测灵敏度、良好的能量分辨率，最后但并非最不重要的一点 可接受的成本。目前，大多数PET系统使用LSO（Lu2SiO5:Ce）或其类似物晶体 LYSO，满足许多列出的要求。但LSO经过多年的发展，已经 达到了性能极限，特别是对于具有长轴向视场 (AFOV) 的扫描仪 目前正在开发中。这些扫描仪的目标是增加几何 覆盖率并显着提高检测灵敏度（30-40 倍），从而减少 扫描时间（快 30-40 倍）或患者的辐射暴露。 然而，长 AFOV 扫描仪面临两个主要挑战： 更大的交互深度 (DOI) 效果，增加模糊和噪音；以及所需体积的增加 组成晶体，约占整个扫描仪成本的 50%。使用 较短的晶体可以抵消 DOI 效应和增加的晶体体积（因此 成本），但检测效率大幅下降，违背了最初的目的。其他 减少 DOI 效应的方法是双端读出，但这会增加成本和 系统复杂性。因此，为了实现可行且经济实惠的长 AFOV 扫描仪，需要一种新的 需要闪烁材料提供比 LSO 更高的阻止能力，具有类似的 或更好的定时特性，并且成本更低。 基于 Lu2O3 的闪烁体可以满足这些要求。这个主机的颜值很高 密度（LSO 为 9.4 g/cm3 vs. 7.4 g/cm3），有效 Z 为 68 vs. 65。当掺杂 Yb3+ 时，它 表现出超快电荷转移 (CT) 发光，衰减时间约为 1 ns， 比 LSO 的 40 ns 快得多。虽然该材料的光输出较低，但其定时特性 与 LaBr3:Ce 配合使用时，具有优于 250 ps 分辨率的 FWHM。唯一的财产 该材料的不足之处在于其能量分辨率（由于其光产量低，在 511 keV 时>15%）。 幸运的是，这个缺点可以通过双掺杂来解决，从而增加其光产量 至约 20,000 ph/MeV。 在这个项目中，我们计划优化Lu2O3的掺杂含量，以最大限度地提高其闪烁度 特性并在 511 keV 下实现约 8% 的能量分辨率和 200 的时间分辨率 附：在第二阶段，我们将增加生产材料的数量，降低成本 方案，并生产和评估具有相同性能目标的 PET 检测模块。