Phase Contrast Cone Beam CT Imaging

描述（由申请人提供）：该项目的目标是发展一种新型的差分相衬锥束计算机断层扫描（DPC-CBCT）技术，使其成为临床有用的乳腺成像诊断工具。这种新型成像技术有可能提供真实的活体乳腺解剖三维图像，其空间分辨率与病理图像相当，同时保持患者剂量与诊断性乳房x光检查相同。基于吸收的x射线成像技术在乳腺成像中显示出其局限性，因为乳腺组织之间的吸收对比度差较低。这个问题的一个解决方案是新兴的相位对比技术，该技术有望在与当前x射线成像方法相当甚至更低的剂量水平下显著增强组织对比度，具有高空间和对比度分辨率。在过去的十年中，各种相衬技术已经发展起来，其中最近报道的一种基于光栅的方法，称为差分相衬（DPC）技术，将用于本项目。DPC的主要优点是可以使用医院级x射线管，而其他相衬技术则需要同步辐射或微聚焦x射线管。由于可用性有限或输出x射线功率极低，这些都不适合广泛的临床应用。该项目的目标是将基于差分相位对比（DPC）的锥形束计算机断层扫描（DPC- cbct）成像系统作为混合系统整合到当前的锥形束乳腺CT （CBBCT）扫描仪中，对CBBCT扫描仪发现的任何可疑肿块进行感兴趣体积（VOI）成像，用于乳腺癌诊断。预计在DPC-CBCT的断层重建切片中，空间分辨率可达25 lp/mm，组织对比度比基于吸收的图像大1000倍以上，因此它应该能够揭示病理水平的细节，从而更准确地表征和诊断乳腺癌。与现有的CBBCT系统结合，有望降低乳腺活检率，准确检测乳腺癌边缘。该项目的具体目标包括：1)通过计算机仿真优化桌面DPC系统设计与构建参数，2)开发VOI DPC-CBCT成像的相位检索算法与重构算法，3)设计构建桌面DPC-CBCT系统，4)评估桌面DPC-CBCT，以桌面实验数据作为混合系统的设计输入，5)设计构建将现有CBBCT扫描仪与DPC-CBCT系统相结合的混合乳腺CT （HBCT）系统。6)用幻影和标本表征混合系统，7)在体内进行小动物研究以验证HBCT， 8)对HBCT系统进行患者试点研究。

DESCRIPTION (provided by applicant): The goal of this project is to develop a novel differential phase contrast cone beam computed tomography (DPC-CBCT) technique into a clinically useful diagnostic breast-imaging tool. Potentially, this novel imaging technique will provide true 3D images of breast anatomy in vivo with spatial resolution comparable to that of pathologic images while maintaining patient dose to that of diagnostic mammography. Absorption-based x-ray imaging techniques have shown their limitations in breast imaging because of low absorption contrast difference among breast tissues. One solution for this issue is the emerging phase- contrast technique that is expected to significantly enhance tissue contrast with high spatial and contrast resolution at comparable or even lower dose level than current x-ray imaging methods. Various phase-contrast techniques have been developed in the past decade, among which a recently reported grating-based method, called differential phase-contrast (DPC) technique, will be used for this project. The major advantage of DPC is that a hospital-grade x-ray tube can be used, while for other phase-contrast techniques synchrotron radiation or a micro-focus x-ray tube is required. These are not practical for widespread clinical applications because of either limited availability or extremely low output x-ray power. This project's goal is to incorporate a differential phase contrast (DPC)-based cone beam computed tomography (DPC-CBCT) imaging system into current cone-beam breast CT (CBBCT) scanner as a hybrid system, to perform volume-of-interest (VOI) imaging of any suspicious mass found by the CBBCT scanner for breast cancer diagnosis. It is anticipated that a spatial resolution of up to 25 lp/mm and a tissue contrast of over a thousand times larger than that of absorption-based images can be achieved in the tomographic reconstruction slices with the proposed DPC-CBCT, and thus it should be capable of revealing pathology-level details for more accurate characterization and diagnosis of breast cancers. When combined with the current CBBCT system, it is expected to reduce the breast biopsy rate and accurately detect breast cancer margins. The specific aims of this project include: 1) Perform computer simulation to optimize the parameters for the design and construction of the table-top DPC system, 2) Develop phase retrieval algorithms and reconstruction algorithms for VOI DPC-CBCT imaging, 3) Design and construct a table-top DPC-CBCT system, 4) Evaluate the table-top DPC-CBCT to use table-top experimental data as design inputs for the hybrid system, 5) Design and construct a hybrid breast CT (HBCT) system combining a current CBBCT scanner with a DPC- CBCT system, 6) Characterize the hybrid system with phantoms and specimens, 7)Perform small animal studies in vivo to validate HBCT, and 8) Perform a patient pilot study on the HBCT system. PUBLIC HEALTH RELEVANCE: The relevance of this research to public health is an expected increase in accuracy for detecting cancer at an earlier size and stage and to obtain a more accurate assessment of the disease extent to reduce cancer burden to the patient. In addition, with this improved accuracy in detecting actual cancers, the potential exists to reduce the number of biopsy procedures ordered; accurately detect breast cancer margin for better treatment plan; monitor cancer treatment response.