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腺成像的X射线计算机断层扫描（CT）成像仪的使用。初步结果表明，与传统的乳腺X线摄影相比，专用乳腺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）低于预期。这些CT原型还测量大量的散射辐射，并且对于位于胸壁附近的乳房组织具有不足的探测器覆盖。这些物理限制将阻止当前的乳腺CT技术在检测和诊断早期乳腺癌方面提供最大的性能。 本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，以提高乳腺专用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操作的半导体探测器，采集螺旋CT几何结构中的投影。世纪以来，临床X射线成像设备已经在能量积分模式下操作，由此通过在有限采集时间上积分X射线事件来形成图像。由于我们在提案中概述的许多原因，能量积分探测器的性能对于在乳房的CT成像中使用是次优的。然而，由于高计数率（即，入射到探测器上的X射线能量密度），历史上不可能在光子计数模式下操作CT探测器。由于X射线探测器和相关电子设备的最新技术改进，光子计数探测器用于乳腺CT应用现已变得可行。 模拟和建模将用于检查这种光子计数X射线CT系统的某些设计规范，并且将通过对乳房体模和新鲜乳房切除标本进行成像来构建和验证原型。使用台式原型的建议CT成像仪，我们将验证其性能，并将其与传统的平板CT乳腺成像仪使用间接转换，能量积分检测器。 公共卫生相关性：专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的3D图像来潜在地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.