Development of a Photon Counting Detector for CT Breast Imaging

描述（由申请人提供）：为了改善乳腺癌的早期检测和诊断，一些研究小组一直在研究专用于乳房成像的 X 射线计算机断层扫描 (CT) 成像仪的使用。初步结果表明，与传统乳房 X 光检查相比，专用乳腺 CT 系统可以提供更好的 3D 乳腺组织可视化效果。然而，当前正在研究的乳腺 CT 原型在所使用的探测器、采集几何结构和信号处理方面存在局限性，导致空间分辨率、病变对比度和信噪比 (SNR) 不尽如人意。这些 CT 原型还测量大量的散射辐射，并且探测器对位于胸壁附近的乳腺组织的覆盖范围不足。这些物理限制将阻碍当前的乳腺 CT 技术在检测和诊断早期乳腺癌方面发挥最大性能。 该提案的总体目标是开发和验证创新的探测器系统和成像方法，以提高乳房专用 CT 成像的性能。我们在此提出的 CT 乳腺成像系统将使用以光子计数模式运行的半导体探测器，获取螺旋 CT 几何形状的投影。一个多世纪以来，临床 X 射线成像设备一直在能量积分模式下运行，通过在有限的采集时间内积分 X 射线事件来形成图像。由于我们在提案中概述的多种原因，能量积分探测器的性能对于乳腺 CT 成像来说并不是最佳的。然而，由于 X 射线 CT 中通常存在高计数率（即，入射到探测器上的 X 射线注量），因此历史上不可能以光子计数模式操作 CT 探测器。由于最近 X 射线探测器和相关电子设备的技术进步，光子计数探测器现在已经可以用于乳腺 CT 应用。 将使用仿真和建模来检查此类光子计数 X 射线 CT 系统的某些设计规范，并将通过对乳房模型和新鲜乳房切除标本进行成像来构建和验证原型。使用所提出的 CT 成像仪的台式原型，我们将验证其性能，并将其与使用间接转换、能量积分探测器的传统平板 CT 乳腺成像仪进行比较。 公共健康相关性：专门用于乳房成像的断层 X 射线成像可以通过为放射科医生提供乳房 3D 图像来改善乳腺癌的检测和诊断。本研究旨在开发一种改进的创新型乳腺 CT 成像探测器系统。

DESCRIPTION (provided by applicant): In an effort to improve the early stage detection and diagnosis of breast cancer, a handful of research groups have been investigating the use of x-ray computerized tomographic (CT) imagers dedicated for use in imaging the breast. Preliminary results suggest that dedicated breast CT systems can provide improved visualization of 3D breast tissue as compared to conventional mammography. However, current breast CT prototypes that are being investigated have limitations in terms of detectors used, acquisition geometry and signal processing that result in less than desirable spatial resolution, lesion contrast, and signal-to-noise (SNR) ratio. These CT prototypes also measure a substantial amount of scattered radiation, and have inadequate detector coverage for breast tissue located near the chest wall. These physical limitations will prohibit current breast CT technology from providing the maximum performance in detecting and diagnosing early-stage breast cancer. The overall goal of this proposal is to develop and validate an innovative detector system and imaging methodology for improved performance in dedicated CT imaging of the breast. The CT breast imaging system that we propose herein will use semiconductor detectors operating in a photon counting mode, acquiring projections in a helical CT geometry. For over a century now, clinical x-ray imaging devices have operated in energy integrating mode, whereby images are formed by integrating x-ray events over a finite acquisition time. For a number of reasons which we outline in the proposal, the performance of energy integrating detectors are sub-optimal for use in CT imaging of the breast. However, due to the high count rate (i.e., x-ray fluence incident on the detector) typically present in x-ray CT, it has historically been impossible to operate CT detectors in a photon counting mode. Due to recent technological improvements in x-ray detectors and associated electronics, it has now become feasible for photon counting detectors to be used for breast CT applications. Simulation and modeling will be used to examine certain design specifications for such a photon- counting x-ray CT system, and a prototype will be constructed and validated by imaging breast phantoms and fresh mastectomy specimens. Using a bench-top prototype of the proposed CT imager, we will validate its performance and compare it to a conventional flat-panel CT breast imager using an indirect conversion, energy integrating detector. PUBLIC HEALTH RELEVANCE: Tomographic x-ray imaging dedicated to imaging of the breast can potentially improve the detection and diagnosis of breast cancer by providing radiologists with 3D images of the breast. This research proposes to develop an improved, innovative detector system for breast CT imaging.