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）来探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是由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有许多局限性：它们相对笨重，它们相对昂贵，它们是脆弱的真空管器件，它们具有相对较低的光量子效率，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态成像。例如，人们对多模态成像越来越感兴趣，它将核医学的功能成像与x射线计算机断层扫描（CT）或磁共振成像（MRI）的优秀结构成像相结合。由于pmt不能在高磁场下工作，因此需要替代光电探测器。固态光电探测器是pmt的一个有吸引力的替代方案，许多研究小组正在积极研究其在放射性核素成像中的应用。这个项目的目标是开发一种比现有性能更好的固态光电探测器。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加工技术，将已经成功应用于气体探测器的放大结构转化为半导体器件。这种新方法的优点是固态光电探测器具有：(1)高粒子检测效率（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分布控制；(3)热噪声低；(4)电容相对较低；(5)由结构的几何参数控制的增益，如通道长度和面积以及施加的电压，这将允许在比例模式或盖革模式下工作。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，成本和紧凑性的光电探测器的前景，这将对核医学成像中先进探测器的发展产生巨大的好处。

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.