Motion Management Using 4D-MRI for Liver Cancer in Radiation Therapy

描述（申请人提供）：呼吸运动对肝癌放疗提出了很大的挑战。4D-CT是目前器官呼吸运动成像的临床标准。但是，1)由于扫描时间较长，对患者的成像剂量较高；2)对肝脏肿瘤成像提供的软组织造影剂不足。相反，MRI具有优异的软组织对比，对临床成像没有已知的辐射危害。因此，基于mri的四维成像（4D- mri）非常需要改善软组织呼吸运动的可视化和运动肝脏肿瘤靶体积的描绘。目前，尚没有一种成熟的4D-MRI放射治疗技术。我们的长期目标是建立一种新的基于4D-MRI的放射治疗运动管理框架。本应用的目的是开发和评估一种临床可行的4D-MRI技术，以改善肝脏肿瘤呼吸运动的成像。我们的总体假设是将4D-MRI整合到肝脏放疗中

DESCRIPTION (provided by applicant): Respiratory motion poses great challenges to radiotherapy of liver cancer. 4D-CT is the current clinical standard for imaging organ respiratory motion. However, it 1) involves high imaging dose to the patient due to prolonged scan time, and 2) provides insufficient soft tissue contrast for imaging liver tumor. Conversely, MRI has excellent soft-tissue contrast and has no known radiation hazard for clinical imaging. MRI-based 4D imaging (4D-MRI) is thus highly desired to improve the visualization of soft-tissue respiratory motion and the delineation of target volume of moving liver tumors. At present, there is no established 4D-MRI technique for radiotherapy. Our long-term goal is to establish a novel 4D-MRI based motion management framework for radiotherapy. The objective of this application is to develop and evaluate a clinical feasible 4D-MRI technique for improved imaging of liver tumor respiratory motion. Our overall hypothesis is that integration of 4D-MRI into radiotherapy of liver cancer will allow for more accurate delineation of tumor internal target volume (ITV). This hypothesis will be tested via two specific aims. Aim 1 will develop and validate a retrospective 4D-MRI technique that can be immediately implemented in the clinic. Aim 2 will evaluate accuracy of the tumor ITV determined from 4D-MRI and its dosimetric impact on treatment planning in liver cancer patient cases. Successful completion of these studies will provide the foundation required to establish a novel 4D-MRI based motion management framework for radiation therapy of liver cancer, and the necessary information to support a later larger scale study to further enhance the 4D-MRI tool. The fully developed 4D-MRI technology will improve our ability to more precisely deliver radiation treatment to tumor and mitigate radiation-induced injury to surrounding normal tissues.