High Performance, Low Cost PET Scintillators

描述（由申请人提供）：正电子发射断层扫描（PET）是一种功能成像技术，具有量化体内生物过程速率的潜力。碳、氮、氧、特别是氟的短寿命正电子发射同位素的可用性使得几乎任何生物学感兴趣的化合物都可以被标记为痕量，并被引入体内用于PET成像。示踪剂的分布动态成像，允许使用适当的数学模型计算生物过程的速率。PET成像可以提供疾病症状的诊断，如癌症、阿尔茨海默病、头部创伤和中风。很明显，PET技术在现代研究和临床诊断中发挥着越来越重要的作用。然而，为了充分利用这种有前途的技术的潜力，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检测器技术的强烈影响。闪烁晶体耦合到光电倍增管目前被用作PET系统中的探测器。对PET系统中使用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、高能量和定时分辨率以及低成本。目前在商业PET扫描仪中使用的传统单晶闪烁器（诸如LSO、BGO和GSO）在性能方面（诸如低光输出、差的比例性和慢响应）或在成本和可用性方面显示出相当大的限制。 由于没有一种成熟的闪烁体能够满足PET的所有规定要求，因此所提出的努力的目标是研究一种新的石榴石闪烁体，该闪烁体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器的能量和时间分辨率超过了现有的PET闪烁器。此外，由于它们的立方结构和相关的物理和光学各向同性，这些石榴石晶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，但仍然具有大量制造的成本效益。这种方法涉及以光学陶瓷（OC）的形式开发石榴石探测器，而不是单晶。将粉末固结成完全致密的陶瓷提供了许多优于传统单晶生长的优点，例如较低的制造温度和较简单的加工设备。 该提议的目的是以完全透明的光学陶瓷的形式生产掺杂有Ce 3+和Pr 3+的新的石榴石闪烁体，其以显著更低的成本和更广泛的可用性显示比目前在PET中使用的最好的单晶更好的闪烁性能。基于光学透明陶瓷石榴石闪烁器的PET成像探测器模块的构建和评估也计划在拟议的努力中。

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.