Phase Contrast Cone Beam CT Imaging

描述(申请人提供)：这个项目的目标是开发一种新的差动相位对比锥束计算机断层扫描(DPC-CBCT)技术，成为临床上有用的诊断乳房成像工具。这种新的成像技术潜在地将提供活体乳腺解剖的真实3D图像，其空间分辨率与病理图像相当，同时保持患者对诊断性乳房X光检查的剂量。由于乳腺组织之间的低吸收对比度差异，基于吸收的X射线成像技术在乳房成像中显示出其局限性。这一问题的一个解决方案是新兴的位相对比技术，它有望以与当前X射线成像方法相当甚至更低的剂量水平，以高空间和对比度分辨率显着增强组织对比度。在过去的十年里，已经发展了各种相位对比技术，其中最近报道的一种基于光栅的方法，称为差分相位对比(DPC)技术，将被用于该项目。DPC的主要优点是可以使用医院级的X射线管，而对于其他相衬技术，则需要同步辐射或微聚焦X射线管。由于可获得性有限或输出X射线功率极低，这些都不适用于广泛的临床应用。该项目的目标是将基于差分相位对比(DPC)的锥束计算机断层扫描(DPC-CBCT)成像系统整合到现有的锥束乳腺CT(CBBCT)扫描仪中，作为一个混合系统，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。预计利用所提出的DPC-CBCT在断层重建切片中可以达到高达25lp/mm的空间分辨率和超过1000倍的基于吸收的图像的组织对比度，因此它应该能够揭示病理水平的细节，以便更准确地描述和诊断乳腺癌。与目前的CBBCT系统相结合，有望降低乳腺活检率，准确检测乳腺癌边缘。本项目的具体目标包括：1)进行计算机模拟以优化桌面DPC系统的设计和构建的参数；2)开发VOI DPC-CBCT成像的相位恢复算法和重建算法；3)设计和构建桌面DPC-CBCT系统；4)评估桌面DPC-CBCT系统以桌面实验数据作为混合系统的设计输入；5)设计和构建结合现有CBBCT扫描仪和DPC-CBCT系统的混合乳腺CT(HBCT)系统；6)用模型和标本来表征混合系统，7)进行活体小动物研究以验证HBCT，以及8)对HBCT系统进行患者先导研究。 与公共健康的相关性：这项研究与公共健康的相关性是，在更早的规模和阶段发现癌症并获得更准确的疾病程度评估，以减轻患者的癌症负担的准确性预期增加。此外，随着检测实际癌症的准确性的提高，有可能减少订购的活组织检查程序的数量；准确地检测乳腺癌边缘，以便更好地制定治疗计划；监测癌症治疗反应。

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.