Fast Photon-Counting CZT Detector for CT Imaging

描述（由申请人提供）：该项目的目标是开发用于CT扫描仪的下一代X射线计算机断层扫描（CT）探测器模块，其基于高通量光子计数碲锌镉（CZT）或碲化镉（CdTe）探测器与CMOS读出阵列的组合。与所有主要CT制造商目前使用的技术相比，这项新技术将显著提高诊断能力。目前市售的CT系统通常使用具有硅（p-n结）光电二极管的检测器，所述光电二极管光学耦合到闪烁体，所述闪烁体以电流积分模式操作，在电流积分模式中，在读出积分电荷之前的一段时间内在每个像素中对从X射线生成的信号进行积分。使用这些电流模式探测器通常会导致图像质量比使用本文所述产品中提出的技术所能实现的图像质量更差。代替在曝光时间上积分X射线电流，高通量光子计数用于在类似的时间段内单独测量和计数每个X射线。高通量是必要的，因为在许多CT应用中使用非常大的X射线通量。例如，CT扫描仪可以在未衰减的光束中产生~100兆光子/mm 2/s。在CT扫描的非常短的时间帧期间，需要大的通量来在透射通量（衰减束）的测量中收集足够的光子统计。这种高计数率与对高检测效率的需要相结合，要求在阶段I中开发检测器结构，该检测器结构在整个检测器厚度上提供比载流子的渡越时间快得多的响应信号。我们将继续开发具有必要功能的探测器模块，以取代现有的CT探测器技术，并提供新的功能：对每个X射线进行计数（和分析），根据X射线能量对事件进行分箱，以及光谱X射线成像功能。这些新功能可实现：显著降低了对患者的X射线剂量，通过光谱X射线成像对组织进行成分分析，以及潜在地显著提高了整体图像质量。公共卫生相关性：到目前为止，所有商业X射线计算机断层扫描（CT）系统都使用集成探测器。通过将高通量光子计数碲锌镉或碲化镉探测器与CMOS读出阵列相结合，我们将在X射线CT性能方面实现重大突破。这些新的特征导致潜在地显著减少对患者的X射线剂量，通过光谱X射线成像对组织进行成分分析，以及潜在地显著改善整体图像质量。

DESCRIPTION (provided by applicant): The goal of the project is to develop the next generation x-ray computed tomography (CT) detector modules for CT scanners based on high-throughput photon-counting cadmium zinc telluride (CZT) or cadmium telluride (CdTe) detectors combined with CMOS readout arrays. This new technology will deliver significant improvements in diagnostic capabilities compared with the technology currently used by all major CT manufacturers. The currently commercially-available CT systems typically use a detector having silicon (p-n junction) photodiodes that are optically coupled to a scintillator which is operated in a current-integrating mode where the signals generated from the x-rays are integrated in each pixel over a time before the integrated charge is read out. The use of these current-mode detectors results in generally poorer image quality than could be achieved by using the technology proposed in the product presented here. Instead of integrating the x-ray current over an exposure time, high-throughput photon counting is used to measure and count each x-ray individually over a similar period. High throughput is necessary as a very large x-ray flux is utilized in many CT applications. For example, CT scanners can produce ~100 Mphotons/mm2/s in the unattenuated beam. The large flux is required to collect sufficient photon statistics in the measurement of the transmitted flux (the attenuated beam) during the very short time frame of a CT scan. This high count rate combined with a need for high detection efficiency required the development in the Phase I of detector structures that provide a response signal much faster than the transit time of carriers over the whole detector thickness. We will continue the development of detector modules with the necessary capabilities to replace existing CT detector technology and provide new features: counting (and analysis) of each individual x-ray, binning events according to x-ray energies, and spectroscopic x-ray imaging capabilities. These new features lead to: significantly reduced x-ray dose to the patient, compositional analysis of tissue through spectroscopic x-ray imaging, and potentially significant improvement in overall image quality. PUBLIC HEALTH RELEVANCE: Until now, all commercial x-ray computed tomography (CT) systems have utilized integrating detectors. By combining high-throughput photon-counting cadmium zinc telluride or cadmium telluride detectors with CMOS readout arrays, we will achieve a significant breakthrough in x-ray CT performance. These new features lead to potentially significantly reduced x-ray dose to the patient, compositional analysis of tissue through spectroscopic x-ray imaging, and potentially significant improvement in overall image quality.