High-Sensitivity Photon-counting X-ray Detector

描述（由申请人提供）：我们将开发用于数字乳房x线摄影的高灵敏度光子计数直接转换x射线探测器。通过将高灵敏度探测器材料碘化汞与最新的CMOS技术光子计数读出相结合，我们将实现x射线探测器的终极性能。与旧技术的x射线探测器相比，仅计数那些落入规定能量窗口的单个x射线的能力具有实质性的性能优势，在旧技术中，所有x射线撞击像素产生的总电荷是唯一可用的信号。新技术通过消除暗电流和读出电路噪声，提高了信噪比。我们可以在不影响图像质量的情况下减少剂量并提高系统吞吐量。这在数字乳房x线摄影筛查中很重要，因为接受检查的健康患者数量很大。这种成像性能的进步是通过利用一种新的直接x射线转换器材料，多晶碘化汞，这是一种高z大带隙化合物半导体而实现的。由于该材料具有出色的电荷收集特性，因此可用于光子计数。我们将x射线变换器直接生长在专门设计的光子计数读出装置上。我们利用新开发的CMOS读出技术，允许我们为阵列中的每个像素放置电荷敏感前置放大器，整形放大器，双鉴别器和数字事件计数器，所有这些都在每个像素的几何区域内。我们希望将该设备作为OEM组件广泛销售给乳房x光检查系统制造商。在项目的第一阶段，我们将设计薄膜沉积技术，产生光谱Hgl2，测试薄膜在玻璃基板上的性能，然后将薄膜沉积在CMOS读出器件上，并测试光子计数和成像性能。在第二阶段，我们将改进CMOS读出芯片的设计，以允许从检测器模块构建面板检测器，根据需要修改Hgl2沉积，并完成乳房x线照相术系统面板检测器原型。第二阶段的面板原型测试将在光子成像和加州大学戴维斯分校医学中心进行。

DESCRIPTION (provided by applicant): We will develop a high-sensitivity photon-counting direct-conversion x-ray detector for digital mammography. By combining a high-sensitivity detector material, mercuric iodide, with newly available CMOS technology photon-counting readouts, we will achieve the ultimate in x-ray detector performance. The ability to count only those individual x-rays which fall into a prescribed energy window gives substantial performance advantages over old technology x-ray detectors where the total charge generated by all of the x-rays hitting a pixel is the only signal available. With the new technology we improve the signal to noise ratio by removing the dark current and readout circuitry noise. We can reduce the dose delivered and improve the system throughput without compromising image quality. This is important in digital mammography screening due to the large number of healthy patients who are examined. This advance in imaging performance is made possible by utilizing a new direct x-ray converter material, polycrystalline mercuric iodide, which is a high-Z large bandgap compound semiconductor. Because it has outstanding charge collection properties, the material can be used for photon counting. We grow the x-ray converter directly onto specially designed photon-counting readout devices. We take advantage of newly-developed CMOS readout technology, allowing us to place a charge-sensitive preamplifier, shaping amplifier, dual discriminators, and digital event counter for each pixel in the array, all within each pixel's geometric area. We expect to widely market the device as an OEM component to mammography system manufacturers. In Phase I of the project we will devise film deposition techniques that produce spectroscopic Hgl2, test the film performance on glass substrates, and then deposit the film on the CMOS readout devices and test for photon counting and imaging performance. In Phase II we will refine the design of the CMOS readout chip to allow a panel detector to be built up from detector modules, modify the Hgl2 deposition as required, and complete a mammography system panel detector prototype. Phase II testing of panel prototypes will be performed at both Photon Imaging and the UC Davis Medical Center.