Innovative Solid-State Photodetector for Applications in Medical Imaging

描述(申请人提供)：核医学成像，如单光子发射计算机断层扫描(SPECT)和正电子发射计算机断层扫描(PET)已成为临床前和临床成像应用的重要工具。大多数用于SPECT和PET的商用相机仍然依靠光电倍增管(PMT)来检测闪烁体中伽马射线转换产生的闪烁光。PMT在核医学中的成功很大程度上归功于它们是非常高增益、快速响应和低噪声的光电探测器。然而，PMT有一些局限性：它们相对笨重，相对昂贵，它们是脆弱的真空管器件，它们的光量子效率相对较低，并且它们不能在高磁场下工作。因此，PMT的使用限制了核医学成像中先进探测器概念的发展，如高分辨率扫描仪和多模式成像。例如，人们对多模式成像越来越感兴趣，它结合了核医学功能成像的能力和X射线计算机断层成像(CT)或磁共振成像(MRI)的优秀结构成像。由于PMT不能在强磁场下工作，因此需要替代光电探测器。固体光电探测器是PMTs的一个有吸引力的替代品，许多小组一直在积极研究它在放射性核素成像中的应用。该项目的目标是开发一种具有比目前可用的更好性能的固态光电探测器。我们提出的器件的新颖和创新的方法是通过先进的半导体和微制造技术将已经成功应用于气体探测器的放大结构转换到半导体器件中。这种新方法的优点是固态光电探测器具有：(1)高粒子探测效率(PDE)；(2)雪崩区域由结构的几何参数控制，而不是由半导体的掺杂浓度和掺杂轮廓控制；(3)低热产生噪声；(4)相对低的电容；以及(5)由结构的几何参数控制的增益，例如沟道长度和面积以及施加的电压，这将允许以比例模式或盖革模式操作。该项目具有PMT的增益和带宽，以及硅光电二极管的量子效率、成本和紧凑性，这将对核医学成像中先进探测器的发展产生巨大的好处。 与公共健康相关：通过发展高分辨率扫描仪和多模式成像等放射性核素医学成像中的先进探测器概念，开发紧凑、低成本、高信噪比、高灵敏度和高增益的固态光电探测器将对国家医疗保健产生重大影响。

DESCRIPTION (provided by applicant): Nuclear medical imaging such as single-photon emission computed tomography (SPECT) and positron emission computed tomography (PET) have become important tools in pre-clinical and clinical imaging applications. Most commercially available cameras used in SPECT and PET still rely on photomultiplier tubes (PMTs) to detect the scintillation light from the conversion of the gamma rays in the scintillator. The success of PMTs in nuclear medicine is largely due to the fact that they are very high-gain, fast-response, and low-noise photodetectors. However, PMTs have a number of limitations: they are relatively bulky, they are relatively expensive, they are fragile vacuum tube devices, they have relatively low optical quantum efficiency, and they cannot operate under high magnetic fields. As a result, the use of PMTs limits the development of advanced detector concepts in nuclear medical imaging such as high-resolution scanners and multi-modality imaging. For example, there is an increasing interest in multimodality imaging, which combines the power of functional imaging of nuclear medicine with the excellent structural imaging of X-ray computed tomography (CT) or magnetic resonance imaging (MRI). Since PMTs cannot operate under high magnetic fields, alternative photodetectors is required. An attractive alternative to PMTs that has been under active investigations by many groups for applications in radionuclide imaging is solid-state photodetectors. The goal of this is project to develop a solid-state photodetector with better performance than currently available. The novel and innovative approach of our proposed device is to translate the amplification structure that has been successfully applied in gaseous detectors to semiconductors devices through advanced semiconductor and microfabrication technology. The advantages of this new approach are solid-state photodetectors with: (1) high particle detection efficiency (PDE); (2) the region of avalanche controlled by the geometric parameters of the structure rather than by the dopant concentrations and dopant profile of the semiconductor; (3) low thermally generated noise; (4) relatively low capacitance; and (5) the gain controlled by the geometric parameters of the structure such as channel length and area as well as the applied voltage, which will allow operation in proportional mode or Geiger mode. This project has the promise of photodetectors with the gain and bandwidth of PMTs and the quantum efficiency, cost, and compactness of silicon photodiodes, which would have a tremendous benefit to the development of advanced detectors in nuclear medical imaging. PUBLIC HEALTH RELEVANCE: The development of compact, low-cost solid-state photodetectors with high signal-to-noise ratio, high sensitivity, and high-gain will have a large impact on national health care through the development of advanced detector concepts in radionuclide medical imaging such as high-resolution scanners and multi-modality imaging.