aSi/CsI FP digital chest imaging with scatter rejection

尽管最近商业化的平板探测器的DQE有所改善，但面阵探测器的投影X射线成像仍然存在两个固有的问题，并降低了低对比度性能：(1)严重衰减区探测器处的低光子通量；(2)缺乏有效的方法来抑制散射辐射。认为这些问题将通过改善DQE得到解决或变得不那么重要的期望有点虚幻。数字探测器的一个主要优点是数字图像处理和分析的前景。然而，这一好处很难实现，因为在图像处理通常最常用的严重衰减区域的信噪比很低。为了解决上述问题，我们提出了一种基于ASI：H和CSI：Tl平板探测器的扫描均衡数字射线成像(SEDR)系统。采用具有区域可调束宽的狭缝扫描成像，以实现有效的散射抑制和曝光均衡。曝光前的图像将被用来计算扫描所需的束宽调制，从而消除使用辐射探测器阵列的需要。一种新的图像读出方案将被用来提供电子后准直，以实现散射抑制，而不衰减主X射线，并且不使用笨重、笨重的后准直器。将实施重新缩放技术，将均衡的数字胸部图像转换为具有传统胸部图像外观的图像，但具有增强的对比度和均衡的信噪比。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。我们将研究并演示使用幻影图像改善图像质量。我们还将进行一项全面的350名患者的ROC研究，以比较扫描均衡DR胸部图像与常规DR图像在进行数字图像增强处理和不进行数字图像增强处理的情况下的差异。该系统有望通过以下方式改善数字胸部图像的低对比度性能：(1)在不衰减原始X射线的情况下更有效地抑制散射辐射；(2)增加严重衰减区域的X射线通量以改善信噪比并减少那里的散射辐射的影响；(3)提供具有改善的对比度噪声比和均衡的信噪比的高质量图像数据，用于进一步的数字图像处理和分析，而不会在严重衰减区域遭受过多的噪声限制。

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.