Ultra-dense ceramic scintillator for BrainPET scanner

摘要 正电子发射断层扫描(PET)是对多种生物进行成像的有力工具 体内过程以及检测和监测人类疾病，以及一个重要的 神经科学研究中的技术。对于人脑研究，PET提供了一种灵敏和 了解大脑新陈代谢和神经化学的无创窗口，提供来自生活的信息 使用任何其他技术都无法获得的人体对象。的主要特征 脑部正电子发射计算机断层成像具有空间分辨率和敏感度。空间分辨率接近的大脑宠物 正在使用LYSO或LSO开发视场(FOV)中心的1 mm 闪烁体，这是目前可用的闪烁体，可以提供最好的整体 性能。然而，要获得较高的灵敏度，这对定量影响很大 为了提高正电子发射计算机成像的精确度，L(Y)所以20毫米左右的厚度被广泛使用。 使用厚的L(Y)SO晶体的第一个也是主要的缺点是平行误差，它 降低偏离FOV中心的空间分辨率。交互深度(DOI)信息 可以用来提高离开视场中心的空间分辨率，然而，最佳DOI 从20 mm厚的L(Y)获得的分辨率是~2.0 mm，使用双端读出，这是 还不够好。L(Y)的第二个缺点是成本太高。对于大多数扫描仪， L(Y)所以成本是扫描仪总成本的一半。 使用一种基于以下原理的新型闪烁体可以提高脑PET扫描仪的性能 Lu2O3(LO)，具有更高的密度(9.4比7.4g/cm3比LSO)和更高的有效Z(68比 LSO为65)。当掺杂La3+和Yb3+时，表现出超快的上升时间(&lt；0.6 ns)。 具有迅速的电荷转移发光，衰减时间为1.7 ns，提供时间分辨率(Tr) 180ps半高宽。在511keV的能量分辨率优于10%(对于lyso为10%)，这是因为 较慢的组件(&lt；20,000 ph/MeV)和良好的比例性(比 Lyso)。因此，Lo：La，Yb可以作为要求较高的脑PET扫描仪的极佳选择 敏感度和高空间分辨率。使用陶瓷方法来制造LO，该陶瓷方法可以 在制造成本方面也比晶体生长方法更具优势。 因此，对于这个项目，我们建议1)优化Lo：La，Yb及其制造 高分辨率和高灵敏度脑部PET的应用，2)优化Lo：La，Yb基PET 通过实验评价用于脑PET的探测器，以及3)评估 基于这些结果的全脑PET系统通过GATE蒙特卡罗模拟和 以Lyso系统为基准。

Summary Positron emission tomography (PET) is a powerful tool for imaging a wide range of biological processes in vivo and for detecting and monitoring human disease, as well as an important technique in neuroscience research. For human brain studies, PET offers a sensitive and noninvasive window into brain metabolism and neurochemistry, providing information from living human subjects that cannot be obtained using any other technique. The key characteristics of brain PET are spatial resolution and sensitivity. Brain PETs with a spatial resolution approaching 1 mm at the center of the field-of-view (FOV) are under development using LYSO or LSO scintillators, which are the currently available scintillators that can provide the best overall performance. However, to obtain a high sensitivity, which strongly affects the quantitative precision of PET imaging, L(Y)SO with a thickness of around 20 mm is widely used. The first and the major drawback of using the thick L(Y)SO crystal is the parallel error, which decreases the spatial resolution off the center of the FOV. Depth-of-Interaction (DOI) information can be used to improve spatial resolution off the center of the FOV, however, the best DOI resolution from 20 mm thick L(Y)SO is ~2.0 mm obtained using the dual-ended readout, which is not good enough. The second drawback of the L(Y)SO is the high cost. For most scanners, the L(Y)SO cost is half of the total scanner cost. The performance of brain PET scanners can be improved using a new scintillator based on Lu2O3 (LO), which has a higher density (9.4 vs. 7.4 g/cm3 for LSO) and higher effective Z (68 vs. 65 for LSO). When doped with La3+ and Yb3+, it exhibits an ultra-fast rise time (<0.6ns) combined with prompt charge transfer luminescence with decay time of 1.7 ns, giving timing resolution (TR) of 180 ps FWHM. The energy resolution at 511 keV is better than 10% (>10% for LYSO), due to the good light yield from slower components (<20,000 ph/MeV) and good proportionality (better than for LYSO). Hence, LO:La,Yb can be an excellent choice for a brain PET scanner requiring high sensitivity and high spatial resolution. The LO is produced using ceramic methods which may also have an edge over the crystal growth methods in terms of cost of manufacturing. Therefore, for this project, we propose to 1) optimize the LO:La,Yb and its manufacturing for high-resolution and high-sensitivity brain PET applications, 2) optimize LO:La,Yb based PET detector for brain PET through experimental evaluation, and 3) to estimate the performance of a full brain PET system based on these results through GATE Monte Carlo simulations and benchmark it against LYSO system.