Development of a Photon Counting Detector for CT Breast Imaging

描述(申请人提供)：为了改进乳腺癌的早期检测和诊断，一些研究小组一直在研究专门用于乳房成像的X射线计算机断层扫描(CT)成像仪的使用。初步结果表明，与传统的乳房X光摄影相比，专用的乳腺CT系统可以提供更好的3D乳腺组织可视化。然而，目前正在研究的乳腺CT原型在使用的探测器、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)较低。这些CT原型还测量了大量的散射辐射，并且对胸壁附近的乳房组织没有足够的探测器覆盖。这些物理限制将阻碍目前的乳腺CT技术在检测和诊断早期乳腺癌方面提供最大的性能。这项提案的总体目标是开发和验证一种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。我们在这里提出的CT乳腺成像系统将使用工作在光子计数模式下的半导体探测器，获取螺旋CT几何结构中的投影。一个多世纪以来，临床X射线成像设备一直运行在能量积分模式下，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一些原因，能量集成探测器的性能不太适合用于乳房的CT成像。然而，由于通常存在于X射线CT中的高计数率(即，入射在探测器上的X射线通量)，在历史上一直不可能在光子计数模式下操作CT探测器。由于最近在X射线探测器和相关电子学方面的技术改进，光子计数探测器现在已经可以用于乳房CT应用。模拟和建模将被用来检查这种光子计数X射线CT系统的某些设计规范，并将通过成像乳房模型和新鲜的乳房切除标本来构建和验证原型。使用所建议的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、能量集成探测器的传统平板CT乳腺成像仪进行比较。 公共卫生相关性：致力于乳房成像的断层X光成像可以为放射科医生提供乳房的3D图像，从而潜在地改善乳腺癌的检测和诊断。这项研究建议开发一种改进的、创新的乳腺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.