High-Sensitivity Photon-counting X-ray Detector

描述(申请人提供)：我们将开发一种用于数字化乳房X光检查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--碘化汞与最新推出的cmos技术光子计数读数相结合，我们将实现最高的x射线探测器性能。与旧技术X射线探测器相比，仅对落入指定能量窗口的单个X射线进行计数的能力提供了实质性的性能优势，在旧技术X射线探测器中，所有X射线击中像素所产生的总电荷是唯一可用的信号。利用新技术，我们通过消除暗电流和读出电路噪声来提高信噪比。我们可以在不影响图像质量的情况下减少传输剂量并提高系统吞吐量。这在数字乳房X光检查中很重要，因为要检查的健康患者数量很多。这种成像性能的提高是通过使用一种新的直接X射线转换材料多晶碘化汞实现的，这是一种高Z大带隙化合物半导体。由于具有优异的电荷收集性能，该材料可用于光子计数。我们将X射线转换器直接生长到专门设计的光子计数读出设备上。我们利用最新开发的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，所有这些都位于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，我们将设计产生光谱Hgl2的薄膜沉积技术，测试薄膜在玻璃基板上的性能，然后将薄膜沉积在CMOS读出设备上，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光摄影系统面板检测器原型。面板原型的第二阶段测试将在光子成像和加州大学戴维斯分校医疗中心进行。

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.