Mainprize James G, Ford Nancy L, Yin Shi, Tümer Türmay, Yaffe Martin J
Department of Medical Biophysics, University of Toronto, Sunnybrook and Women's College Health Sciences Centre, Ontario, Canada.
Med Phys. 2002 Feb;29(2):214-25. doi: 10.1118/1.1446108.
We have developed a novel direct conversion detector for use in a slot-scanning digital mammography system. The slot-scan concept allows for dose efficient scatter rejection and the ability to use small detectors to produce a large-area image. The detector is a hybrid design with a 1.0 mm thick silicon PIN photodiode array (the x-ray absorber) indium-bump bonded to a CCD readout that is operated in time-delay integration (TDI) mode. Because the charge capacity requirement for good image quality exceeds the capabilities of standard CCDs, a novel CCD was developed. This CCD consists of 24 independent sections, each acting as a miniature CCD with eight rows for TDI. The signal from each section is combined off-chip to produce a full signal image. The MTF and DQE for the device was measured at several exposures and compared to a linear systems model of signal and noise propagation. Because of the scanning nature of TDI imaging, both the MTF(f) and DQE(f) are reduced along the direction of the scanning motion. For a 26 kVp spectrum, the DQE(0) was measured to be 0.75+/-0.02 for an exposure of 1.29 x 10(-5) C/kg (50 mR).
我们开发了一种新型直接转换探测器，用于缝隙扫描数字乳腺摄影系统。缝隙扫描概念允许高效剂量散射抑制，并能够使用小型探测器生成大面积图像。该探测器采用混合设计，一个1.0毫米厚的硅PIN光电二极管阵列（X射线吸收器）通过铟凸块键合到一个以延时积分（TDI）模式运行的CCD读出器上。由于良好图像质量所需的电荷容量超过了标准CCD的能力，因此开发了一种新型CCD。该CCD由24个独立部分组成，每个部分都作为一个具有八行用于TDI的微型CCD。每个部分的信号在芯片外进行组合，以产生完整信号图像。在几次曝光下测量了该设备的调制传递函数（MTF）和量子探测效率（DQE），并与信号和噪声传播的线性系统模型进行了比较。由于TDI成像的扫描特性，MTF（f）和DQE（f）在扫描运动方向上都会降低。对于26 kVp的能谱，在1.29×10^(-5) C/kg（50 mR）的曝光下，测量得到的DQE（0）为0.75±0.02。
