High Performance, Low Cost PET Scintillators

描述(申请人提供)：正电子发射断层扫描(PET)是一种功能成像技术，有可能量化体内生物过程的速率。碳、氮、氧，特别是氟的短命正电子发射同位素的存在，使得几乎任何具有生物意义的化合物都可以被微量标记，并被引入体内进行PET成像。示踪剂的分布是动态成像的，允许使用适当的数学模型来计算生物过程的速率。宠物成像可以为癌症、阿尔茨海默病、头部创伤和中风等疾病的症状提供诊断。很明显，PET技术在现代研究和临床诊断中发挥着越来越明显的作用。然而，为了充分发挥这一前景广阔的技术的潜力，迫切需要提高PET系统的性能并降低其成本。这两个因素都受到现有探测器技术的强烈影响。与光电倍增管耦合的闪烁晶体目前被用作PET系统中的探测器。用于PET系统的闪烁晶体的重要要求包括快速响应、高灵敏度、高光输出、良好的比例性、高能量和高时间分辨率以及低成本。目前用于商业PET扫描仪的传统单晶闪烁体(如LSO、BGO和GSO)在性能方面(如低光输出、比例差和响应慢)或在成本和可用性方面都存在相当大的局限性。由于没有一种成熟的闪烁体能够满足PET的所有规定要求，建议的努力的目标是研究一种新的石榴石闪烁体，它可以提供高伽马射线阻止效率、高光产额和快速衰减时间。这些新的石榴石闪烁体的能量和时间分辨率超过了现有的PET闪烁体。此外，由于它们的立方结构以及相关的物理和光学各向同性，这些石榴石闪烁体可以使用陶瓷制造技术制造，其性能与最好的晶体相媲美，但对于大批量制造仍然具有成本效益。这种方法包括开发光学陶瓷(OCS)形式的石榴石探测器，而不是单晶体。与传统的单晶生长相比，将粉末固化成完全致密的陶瓷具有许多优点，例如较低的制造温度和更简单的加工设备。这项提议的目的是以全透明光学陶瓷的形式制备掺杂Ce3和Pr3的新型石榴石闪烁体，其闪烁性能优于目前用于PET的最佳单晶，且成本显著降低，可获得性更广。在拟议的工作中还计划建造和评估基于光学透明陶瓷石榴石闪烁体的PET成像探测器模块。

DESCRIPTION (provided by applicant): Positron Emission Tomography (PET) is a functional imaging technique with the potential to quantify the rates of biological processes in vivo. The availability of short-lived positron-emitting isotopes of carbon, nitrogen, oxygen and especially fluorine allows virtually any compound of biological interest to be labeled in trace amounts and introduced into the body for imaging with PET. The distribution of the tracer is imaged dynamically, allowing the rates of biological processes to be calculated using appropriate mathematical models. PET imaging can provide diagnosis for symptoms of diseases such as cancer, Alzheimer's disease, head trauma, and stroke. It is clear that PET technology is playing a prominent and increasingly visible role in modern research and clinical diagnosis. However, to allow exploitation of the full potential of this promising technique, there is urgent need for both improvement in the performance of PET systems and reduction in their cost. Both of these factors are strongly influenced by the available detector technology. Scintillation crystals coupled to photomultiplier tubes are currently used as detectors in PET systems. Important requirements for the scintillation crystals used in PET systems include fast response, high sensitivity, high light output, good proportionality, high energy and timing resolution, and low cost. Traditional single crystals scintillators (such LSO, BGO and GSO) which are currently used in commercial PET scanners show considerable limitations either in performance aspects (such as low light output, poor proportionality and slow response) or in cost and availability aspects. With none of the well-established scintillators able to satisfy all the stated requirements of PET, the goal of the proposed effort is to investigate a new garnet scintillator that provides high gamma-ray stopping efficiency, high light yield, and fast decay time. The energy and timing resolution of these new garnetscintillators surpass those for the existing PET scintillators. Furthermore, due to their cubic structure and the associated physical and optical isotropy, these garnet scintillators can be fabricated using ceramic fabrication techniques, with properties rivaling those of the best crystals, yet remaining cost effective for fabrication in large quantities. This approach involves developing garnet detectors in the form of optical ceramics (OCs), rather than the single crystals. Consolidation of powder into a fully dense ceramic provides many advantages over traditional single crystal growth, such as lower fabrication temperatures and simpler processing equipment. It is the aim of this proposal to produce new garnet scintillators doped with Ce3+ and Pr3+ in the form of a fully transparent optical ceramics, which display scintillation performance better than that of best single crystals used currently in PET at significantly lower cost with wider availability. Construction and evaluation of detector modules for PET imaging based on optically transparent ceramic garnet scintillators is also planned in the proposed effort.