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

描述（申请人提供）：呼吸运动对肝癌放射治疗提出了巨大挑战。4D-CT是当前用于成像器官呼吸运动的临床标准。然而，1）由于延长的扫描时间，其涉及对患者的高成像剂量，以及2）为肝肿瘤成像提供的软组织对比度不足。相反，MRI具有出色的软组织对比度，并且对于临床成像没有已知的辐射危害。因此，非常需要基于MRI的4D成像（4D-MRI）来改善软组织呼吸运动的可视化和移动肝脏肿瘤的靶体积的描绘。目前，还没有建立用于放射治疗的4D-MRI技术。我们的长期目标是建立一个新的基于4D-MRI的放射治疗运动管理框架。本申请的目的是开发和评价一种临床可行的4D-MRI技术，用于改善肝脏肿瘤呼吸运动的成像。我们的总体假设是，4D-MRI与肝脏放射治疗的整合 癌症将允许更准确地描绘肿瘤内部靶体积（ITV）。这一假设将通过两个具体目标进行检验。目标1将开发和验证一种可立即在临床上实施的回顾性4D-MRI技术。目的2将评估从4D-MRI确定的肿瘤ITV的准确性及其对肝癌患者病例治疗计划的剂量学影响。这些研究的成功完成将为建立一个新的基于4D-MRI的肝癌放射治疗运动管理框架提供必要的基础，并提供必要的信息来支持以后更大规模的研究，以进一步增强4D-MRI工具。全面发展的4D-MRI技术将提高我们更精确地对肿瘤进行放射治疗的能力，并减轻对周围正常组织的辐射损伤。

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.