Development of novel PET detectors based on Geigermode Avalanche Photodiodes (G-APDs) for Molecular Imaging Applications

这项拨款的重点是开发基于新型半导体光电二极管和快速读出电子设备的先进正电子发射断层扫描（PET）探测器。传统的PET探测器是基于一组闪烁晶体——将伽马射线转换成微弱的闪光——和高灵敏度、低噪音和快速光电倍增管（PMT），后者探测闪烁光。这些光电探测器体积庞大，成本相对较高，不适合PET/MRI等多模态医学成像设备。作为pmt的替代品，雪崩光电二极管（apd）目前是基于半导体的，结构非常紧凑，但电子增益比pmt低约10³，时序分辨率也比pmt差。这影响了PET成像质量和定量精度。最近，高能物理研究小组专注于开发所谓的盖格模式apd (g - apd)，它提供了标准apd的所有优点，但具有与pmt相当的增益，可以解析单个光电子，在更低的电压下工作，并且具有出色的时序分辨率。此外，由于标准的CMOS生产技术，这些gapd探测器的未来成本应该比apd或pmt低得多。本提案建议的工作重点是研究g - apd在高分辨率PET应用中的适用性。我们将开发一种新型的探测器，它可以在高磁场下工作，用于PET/MRI组合，并提供深度的相互作用信息，以获得最佳的空间分辨率。此外，将开发专门用于g - apd的快速读出电子设备。

This grant focuses on the development of advanced detectors for positron emission tomographs (PET) based on novel semiconductor photodiodes and fast readout electronics. Conventional PET detectors are based on an array of scintillation crystals - which convert the gamma rays into weak light flashes - and highly sensitive, low noise and fast photomultiplier tubes (PMT), which detect the scintillation light. These photodetectors are bulky and relatively cost-intensive and are not suited for multimodality medical imaging devices such as PET/MRI. As alternative to PMTs serve currently avalanche photodiodes (APDs), which are semiconductor-based and very compact but provide about 10³ lower electronic gain and worse timing resolution than PMTs. This impacts the PET image quality and quantification accuracy. Recently, high energy physics research groups focussed on the development of so-called Geiger-mode APDs (G-APDs) which provide all the advantages of standard APDs but have a gain comparable to that of PMTs, resolve single photoelectrons, operate at much lower voltage and have an exceptional timing resolution. Also, the future costs for these GAPDs detectors should be much lower than for APDs or PMTs because of the standard CMOS production technology. The work suggested in this proposal focus on the investigation of G-APDs for their suitability to be used in high resolution PET applications. We will develop a novel detector which works in high magnetic fields for combined PET/MRI and provides depth of interaction information for best achievable spatial resolution. Furthermore, fast readout electronics, specifically for G-APDs, will be developed.