A cost-effective high-performance ceramic garnet scintillator for PET

描述(由申请人提供)：正电子发射断层扫描(PET)扫描仪的性能在很大程度上取决于闪烁体的特性和尺寸 用于形成探测器的元素。闪烁体材料的关键性能包括其亮度、阻止能力和衰减时间。由于它在核医学成像中的基本重要性，以及目前闪烁体材料的局限性，对新探测器材料的研究仍然活跃。在这个方案中，我们研究了稀土石榴石(GdxLu1-x)3(GaAl1-y)5O12：Ce(简称GLuGAG)作为PET探测器闪烁体的可能性。它具有前所未有的性能组合，包括高阻挡能力(511keV时衰减长度1.3厘米)，高产光率(约66,000光子/MeV沉积)和快速衰减时间(约40 ns)，而且与大多数其他非常明亮的闪烁体不同，它不是湿气 很敏感。因为它具有立方晶体结构，所以也可以用陶瓷技术来制造。这使得这种材料可以在更低的温度下制备，比传统的单晶闪烁体生长得更快。它还提供了诱人的可能性，可以直接制造所需大小和形状的闪烁体元件，而不需要切割。因此，与传统闪烁体相比，陶瓷闪烁体有可能产生成本低得多的材料。几年来对GLuGAG的开发和表征工作已经完成，在这个阶段，可以使用陶瓷技术可靠地制造具有优异性能的小样本材料。这项提议的目标是：i)微调 为了最大限度地减少衰减时间和最大化光输出；ii)充分表征GLuGAG的闪烁特性；iii)扩大材料的生产体积，使其足以容纳完整的PET块探测器单元；iv)研究直接制造尺寸和形状所需的元件；v)表征用于PET应用的适当尺寸的GLuGAG元件在能量分辨率和时间分辨率方面的性能；vi)建造和评估成对完整的PET探测器模块，以便与现有商业探测器在空间分辨率、效率、能量和时间分辨率方面的性能进行比较。我们还将探索更先进的PET探测器设计，具有用于深度编码的双端读出，并使用大面积硅光电倍增管技术读出GLuGAG闪烁体阵列。GLuGAG出色的闪烁性能与使用陶瓷方法制造高透明度的能力相结合(这是任何其他密度合理的PET应用闪烁体所不具备的特性)，提供了巨大的潜力，可以有利地显著改变PET探测器设计中的成本/性能权衡，从而影响从临床到小动物研究的所有PET应用。 公共卫生相关性：正电子发射断层扫描(PET)是一种广泛应用于临床和生物医学研究的成像技术。这项建议研究了一种新的闪烁探测器材料，这种材料可以使用简单的陶瓷技术制造，并有可能显著提高临床和研究用PET扫描仪的性能并降低成本。这项研究的影响是，它可以通过降低成本帮助PET更广泛地获得，还可以产生更准确的重建图像，这可能会对其诊断和研究用途产生积极影响。

DESCRIPTION (provided by applicant): The performance of positron emission tomography (PET) scanners is dictated, to a large extent, by the properties and dimensions of the scintillator elements used to form the detectors. Critical properties of the scintillator material include its brightness, its stopping power and its decay time. Because of its fundamental importance in nuclear medicine imaging, and the limitations of current scintillator materials, research into new detector materials remains active. In this proposal, we study the potential for a rare-earth garnet, (GdxLu1-x)3(GayAl1-y)5O12:Ce (abbreviated as GLuGAG) to be used as a scintillator in PET detectors. It has an unprecedented combination of properties, including high stopping power (attenuation length 1.3 cm at 511 keV), high light yield (~66,000 photons/MeV deposited) and a fast decay time (~40 ns), and unlike most other very bright scintillators, it is not moisture sensitive. Because it has a cubic crystal structure, it also can be fabricated using ceramic techniques. This allows the material to be made at lower temperatures and more quickly than conventional scintillators grown as single crystals. It also offers tantalizing possibilities for directly fabricating scintillator elements in the desired size and shape with no cutting. Ceramic scintillators therefore have the potential to result in much lower cost materials compared with traditional scintillators. Several years of development and characterization work on GLuGAG has been completed and at this stage small samples of materials with excellent properties can be reliably fabricated using ceramic techniques. The goals of this proposal are to i) fine-tune the composition of GLuGAG to minimize the decay time and maximize the light output; ii) to fully characterize the scintillation properties of GLuGAG; iii) to scale up the volume of material produced such that it is large enough for a complete PET block detector unit; iv) to investigate directly fabricating elements in the size and shape required; v) to characterize the performance of GLuGAG elements of appropriate sizes for PET applications in terms of energy resolution and timing resolution; vi) and to build and evaluate pairs of complete PET detector modules for comparison against the performance of existing commercial detectors in terms of spatial resolution, efficiency, energy and timing resolution. We also will explore more advanced PET detector designs with dual-ended readout for depth- encoding, and read out of GLuGAG scintillator arrays using large-area silicon photomultiplier technology. The combination of GLuGAG's outstanding scintillation properties, and the ability to fabricate it with high transparency using ceramic approaches (a feature not shared by any other scintillator with plausible density for PET applications) offers tremendous potential to favorably and significantly shift the cost/performance trade-off in PET detector design, thereby impacting all applications of PET from the clinic through small-animal research. PUBLIC HEALTH RELEVANCE: Positron emission tomography (PET) is a widely used imaging technology both for clinical applications and in biomedical research. This proposal studies a new scintillation detector material that can be fabricated using straightforward ceramic techniques, and that has the potential to significantly improve the performance and lower the cost of PET scanners designed both for clinical and research purposes. The impact of this research is that it could help make PET more widely available by lowering cost, and also could lead to more accurate reconstructed images that could positively impact on its diagnostic and research uses.