aSi/CsI FP digital chest imaging with scatter rejection

尽管最近商业化的平板检测器的DQE得到了改进，但是具有区域检测器的投影X射线成像固有的两个问题仍然存在并且降低了低对比度性能：（1）在严重衰减区域中的检测器处的低光子注量，以及（2）缺乏有效的方法来拒绝散射辐射。 期望通过改进DQE来解决这些问题或使其变得不那么重要是有点虚幻的。 数字检测器的一个主要好处是数字图像处理和分析的前景。 然而，由于在图像处理通常最常用的严重衰减区域中的低信噪比，这种益处难以实现。为了解决上述问题，我们建议构建和研究一个扫描均衡数字X射线摄影（SEDR）系统使用aSi：H和CsI：Tl的平板探测器。 将使用具有区域可调光束宽度的狭缝扫描成像来实现有效的散射抑制和曝光均衡。 预曝光图像将用于计算扫描所需的光束宽度调制，从而消除了使用辐射探测器阵列的需要。 一种新的图像读出方案将用于提供电子后准直，以实现散射抑制，而不衰减初级X射线，而不使用沉重，笨重的后准直器。将实施重新缩放技术，以将均衡的数字胸部图像转换为具有传统胸部图像外观但具有增强的对比度和均衡的SNR的图像。 为了评估所提出的技术，我们将测量和表征所提出的SEDR系统的性能。 我们将研究并证明体模图像的图像质量改善。 我们还将进行一项全面的350例患者ROC研究，以比较扫描均衡DR胸部图像与常规DR图像（进行和不进行数字图像增强处理）。所提出的系统预期通过以下方式改善数字胸部图像的低对比度性能：（1）更有效地抑制散射辐射而不衰减初级X射线，（2）增加严重衰减区域中的X射线注量以改善SNR并减少那里的散射辐射的影响，（3）提供具有改善的对比度的高质量图像数据，噪声比和均衡的SNR，用于进一步的数字图像处理和分析，而不会在严重衰减的区域中遭受过度的噪声限制。

Despite improved DQEs of recently commercialized flat- panel detectors, two problems intrinsic to projection x-ray imaging with area detectors remain and degrade the low contrast performance: (1) low photon fluences at the detector in heavily attenuated regions, and (2) lack of efficient methods to reject scattered radiation. The expectation that these problems would be resolved or become less important through improved DQEs is somewhat illusive. One major benefit with digital detectors is the prospect of digital image processing and analysis. However, this benefit is hard to realize due to the low signal-to-noise ratios in heavily attenuated regions where image processing often finds most use. To resolve the above mentioned problems, we propose to construct and investigate a scanning equalization digital radiography (SEDR) system using an aSi:H and CsI:Tl based flat-panel detector. Slit scanning imaging with regionally adjustable beam width will be used to achieve effective scatter rejection and exposure equalization. A pre-exposure image will be used to compute the necessary beam width modulations for the scan, eliminating the need for using a radiation detector array. A novel image readout scheme will be used to provide electronic aft-collimation to achieve scatter rejection without attenuating primary x-rays and without using a heavy, bulky aft-collimator. A re-scaling technique will be implemented to convert equalized digital chest images into images with the appearance of conventional chest images but with enhanced contrast and equalized SNRs. To evaluate the proposed technique, we will measure and characterize the performance of the proposed SEDR system. We will study and demonstrate image quality improvements with phantom images. We will also conduct a comprehensive 350 patient ROC study to compare the scanning equalization DR chest images with regular DR images with and without digital image enhancement processing. The proposed system is expected to improve the low contrast performance of digital chest images by: (1) more effectively rejecting scattered radiation without attenuating primary x-rays, (2) increasing x-ray fluences in heavily attenuated regions to improve SNRs and reduce impact of scattered radiation there, (3) providing high quality image data with improved contrast-to-noise ratios and equalized SNRs for further digital image processing and analysis without suffering excessive noise limitations in heavily attenuated regions.