Image Science for the New X-Ray: Taking Dual-Energy CT to Task

描述（由申请人提供）：第一个世纪的医学x射线成像通过投影成像和计算机断层扫描（CT）提供了前所未有的进步，第二个世纪将以更智能的应用和利用x射线光谱和断层成像信息、新型源探测器配置和辐射剂量最小化为标志。最近在低剂量CT、双能CT （DE）和锥束CT （CBCT）方面的研究证明了这一点，在最近关于CT应用的科学和大众交流中也非常清楚。DE-CT的应用见于腹部（如肾结石）、肌肉骨骼（MSK，如关节炎）和神经（如灌注）成像。光谱/层摄影技术知识进步的关键是性能评估和优化的基础，它不仅考虑了x射线探测和图像重建的物理特性，而且考虑了成像任务-此外-以一种最大化任务性能同时最小化辐射剂量的方式。该项目更新建立在原始R01的成功基础上，其中基于任务的成像性能框架扩展到DE成像和CBCT，提供：i.)从基本傅立叶域指标（如噪声等效量子（NEQ））到真实和模型观测器性能的桥梁；ii.)优化新的DE和CBCT技术的定量框架；iii)加速新技术转化为关键临床应用的方法。通过结合DE成像和CBCT模型，目前的工作旨在开发DE-CBCT成像性能框架，解决新探测器技术和图像分解技术方面的挑战，并将结果专门应用于MSK成像的新型DE-CBCT原型。该提案的目的是：1)；建立基于任务的DE-CBCT性能模型框架，将NEQ与特定的检测/鉴别任务联系起来，并为系统优化和剂量最小化提供基础；2)。将框架扩展到能量集成和能量鉴别探测器技术（即平板探测器和光子计数器），并在幻影和尸体中验证与台式测量的性能；3)。将框架扩展到基于重建和基于投影的DE-CBCT图像分解，包括降噪算法，以阐明每种算法的优势并优化在特定成像任务中的实现；和4)。将结果转化为原型MSK四肢CBCT扫描仪（已经在一个单独的项目中构建），以实现和评估MSK成像任务（例如钙-碘、钙-尿酸和内在软组织鉴别）中的最佳DE-CBCT技术。这项工作的成功完成为评估新的和现有的DE-CT/CBCT系统提供了一个定量框架，为这种快速发展的技术的知识翻译提供了指南，为最小化成像任务的辐射剂量提供了定量基础，并在MSK成像（例如骨关节炎、痛风、软组织和骨肿瘤以及组织撞击综合征）的应用方面取得了具体进展。

DESCRIPTION (provided by applicant): While the first century of medical x-ray imaging offered an unprecedented advance via projection imaging and computed tomography (CT), its second century will be marked by more intelligent application and utilization of x-ray spectral and tomographic information, novel source-detector configurations, and minimization of radiation dose. Such is evidenced by recent work in low-dose CT, dual-energy (DE) CT, and cone-beam CT (CBCT) and is crystal clear in recent scientific and popular communication of CT utilization. Application of DE-CT is seen in abdominal (e.g., renal calculi), musculoskeletal (MSK, e.g., arthritis), and neuro (e.g., perfusion) imaging. Key to the knowledgeable advance of spectral / tomographic techniques is a basis for performance assessment and optimization that considers not only the physics of x-ray detection and image reconstruction, but also the imaging task - and moreover - in a manner that maximizes task performance while minimizing radiation dose. This project renewal builds on the success of the original R01 in which a task-based framework for imaging performance was extended to DE imaging and CBCT, providing: i.) a bridge from fundamental Fourier-domain metrics such as noise-equivalent quanta (NEQ) to real and model observer performance; ii.) a quantitative framework for optimization of new DE and CBCT technologies; and iii.) an approach shown to accelerate translation of new technology knowledgeably to key clinical applications. By combining the models for DE imaging and CBCT, the current work aims to develop a framework for imaging performance in DE-CBCT, tackling challenges that beckon in regard to new detector technologies and image decomposition techniques and applying the results specifically to a novel DE-CBCT prototype for MSK imaging. The aims of the proposal are to: 1.) Establish a model task-based framework for DE-CBCT performance that relates NEQ to specific detection / discrimination tasks and provides a basis for system optimization and dose minimization; 2.) Extend the framework to energy-integrating and energy-discriminating detector technology (viz., flat-panel detectors and photon counters) and validate performance versus benchtop measurements in phantom and cadaver; 3.) Extend the framework to reconstruction-based and projection-based DE-CBCT image decomposition, including noise reduction algorithms, to elucidate the advantages of each and optimize implementation in specific imaging tasks; and 4.) Translate the results to a prototype MSK extremities CBCT scanner (already constructed in a separate project) to implement and evaluate optimal DE-CBCT techniques in MSK imaging tasks (e.g., calcium-iodine, calcium-uric acid, and intrinsic soft-tissue discrimination). Successful completion of the work offers a quantitative framework for evaluation of new and existing DE-CT/CBCT systems, a guide to knowledgeable translation of this rapidly proliferating technology, a quantitative basis for minimizing radiation dose with respect to the imaging task, and a specific advance in application to MSK imaging (e.g., osteoarthritis, gout, soft-tissue and bone tumors, and tissue impingement syndromes).