Ultra-dense and Fast Ceramic Scintillator for PET

项目摘要 目前PET中的探测器技术要求闪烁具有快速响应、出色的 时间分辨率、高检测灵敏度、良好的能量分辨率，最后但并非最不重要 可接受的成本。目前，大多数聚酯系统使用LSO(Lu2SiO5：Ce)晶体或其类似物 Lyso，这满足了许多列出的要求。但LSO经过多年的发展，已经 达到其性能极限，特别是对于长轴向视场(AFOV)的扫描仪 目前正在开发中的。这些扫描仪的目标是增加几何形状 覆盖范围并显著提高检测灵敏度(提高30-40倍)，从而降低 扫描时间(快30-40倍)或患者的辐射照射。 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，这会增加模糊和噪声；以及增加 构成晶体，约占整个扫描仪成本的50%。对.的使用 较短的晶体可以抵消DOI效应和增加的晶体体积(因此 成本)，但极大地损失了检测效率，违背了最初的目的。另一个 减少DOI影响的方法是双端读出，但这增加了成本和 系统复杂性。因此，为了实现可行和负担得起的长AFOV扫描仪，一种新的 闪烁材料需要提供比LSO更强的阻止能力，对于类似的 或者更好的定时特性，并且以较低的成本。 基于Lu2O3的闪烁体可以满足这些要求。这位主持人的支持率非常高 密度为9.4克/厘米~3，LSO为7.4克/厘米~3)，有效Z为68分，65分。当掺入Yb3+时， 表现出衰减时间约为1 ns的超快电荷转移(CT)发光， 比LSO的40纳秒要快得多。虽然这种材料的光产额很低，但它的计时特性 与LaBr3：Ce配合使用时，具有优于250 ps的分辨率半高宽。唯一的财产 材料的不足之处在于其能量分辨率(由于其低的光产额，在511keV时的分辨率为15%)。 幸运的是，这一缺点可以通过双掺杂来解决，这增加了它的光产额 降到大约20,000每小时/兆瓦。 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 并在511keV和200的时间分辨率下实现了约8%的能量分辨率 PS.在第二阶段，我们将增加生产资料的数量，发展降低成本 方案，并生产和评估具有相同性能目标的PET检测模块。

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.