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，该探测器基于高通量光子计数碲化镉锌(CZT)或碲化镉(CdTe)探测器，并结合CMOS读出阵列。与所有主要CT制造商目前使用的技术相比，这项新技术将在诊断能力方面带来重大改进。当前商业上可用的CT系统通常使用具有硅(p-n结)光电二极管的探测器，该探测器光学耦合到闪烁体，闪烁体以电流积分模式操作，其中在读出积分电荷之前的一段时间内，从X射线产生的信号被积分在每个像素中。使用这些电流模式检测器通常会导致图像质量比使用本文介绍的产品中提出的技术所能实现的图像质量更差。高通量光子计数不是在曝光时间内对X射线电流进行积分，而是在类似的时间段内分别测量和计数每一条X射线。由于在许多CT应用中使用非常大的X射线通量，因此需要高吞吐量。例如，CT扫描仪可以在无衰减光束中产生~100M光子/毫米~2/S。在CT扫描的极短时间帧期间，在测量传输的通量(衰减束)时，需要大的通量来收集足够的光子统计数据。这种高的计数速率与对高检测效率的需求相结合，需要在阶段I中开发检测器结构，其提供响应信号的速度比载流子在整个检测器厚度上的传输时间快得多。我们将继续开发具有必要能力的探测器模块，以取代现有的CT探测器技术，并提供新的功能：对每条单独的X射线进行计数(和分析)，根据X射线能量对事件进行分类，以及光谱X射线成像能力。这些新功能导致：患者的X射线剂量显著减少，通过光谱X射线成像对组织进行成分分析，并潜在地显著提高整体图像质量。与公共卫生相关：到目前为止，所有商业X射线计算机断层扫描(CT)系统都使用了集成探测器。通过将高通量光子计数碲化镉锌或碲化镉探测器与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。这些新功能可能会显著降低患者的X射线剂量，通过光谱X射线成像对组织进行成分分析，并可能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.