Image-Guided IMRT for Inter-Fractional Changes

描述（由申请人提供）：本次竞争性更新申请的主要目的是研究一系列图像引导IMRT （IG-IMRT）策略的适当性和相关部位特异性临床潜力，以考虑解剖结构的分数间变化。我们的假设是，应用不同复杂程度和复杂性的适当IG-IMRT策略将导致更适形的剪裁和更高的递送剂量分布准确性，从而显著减少暴露于破坏性辐射剂量水平或肿瘤剂量增加的正常组织，或两者兼而有之。有许多可能的IG-IMRT策略，包括一些非常先进和复杂的策略，涉及每日ct图像引导设置和在线近实时重新规划。对于特定部位的临床情况，每种策略的适当性将作为本研究计划的一部分确定，并将取决于分数间解剖变异的大小和性质、治疗技术（例如，立体定向、低分数）以及成本与临床效益的考虑。为了验证我们的假设，我们将(1)适应、优化、开发，必要时，并评估图像分割和可变形配准方法的有效性；(2)开发和评估针对不同的离线和在线适应性和纠正性IG-IMRT策略设计和交付IMRT的方法和软件；(3)进行临床前治疗设计研究，通过将IG-IMRT替代策略应用于前列腺、头颈部和视频反馈引导的门控或屏气肺治疗，评估它们相对于当前实践以及彼此之间的优点。提出这项研究的临床依据是，从长远来看，其结果将在降低正常组织毒性、提高局部控制性或两者兼而有之方面显著改善结果。此外，对实际剂量分布的准确了解将提高剂量-反应数据的质量。为了实现我们的目标，我们打算利用我们在前两个资助周期中通过IMRT研究取得的进展。

DESCRIPTION (provided by applicant): The main goal of this competitive renewal application is to investigate the appropriateness and the relative site- specific clinical potential of a range of image-guided IMRT (IG-IMRT) strategies for taking into account inter-fractional changes in anatomy. Our hypothesis is that the application of appropriate IG-IMRT strategies of varying sophistication and complexity will lead to more conformal tailoring and to higher accuracy of delivered dose distributions, allowing significant reduction of normal tissues exposed to damaging levels of radiation doses or escalation of tumor doses, or both. There are many possible IG-IMRT strategies, including some that are highly advanced and complex ones that involve daily CT-image-guided setup and online near real-time replanning. The appropriateness of each strategy for a given site-specific clinical situation will be determined as a part of this research proposal and will depend upon the magnitude and the nature of the inter-fractional anatomic variations, the treatment technique (e.g., stereotactic, hypo-fractionated) and cost vs. clinical benefit considerations. To test our hypothesis, we will (1) adapt, optimize, develop, where necessary, and evaluate the effectiveness of image segmentation and deformable registration methods; (2) develop and evaluate methods and software for designing and delivering IMRT specifically for different offline and online adaptive and corrective IG-IMRT strategies; and (3) conduct preclinical treatment design studies to assess the merits of alternate IG-IMRT strategies relative to current practices as well as to each other by applying them to cases of prostate, head-and-neck and video-feedback-guided gated or breath-hold lung treatments. The clinical rationale for the proposed research is that its results will, in the long run, lead to significant improvements in outcome in terms of lower normal tissue toxicity, higher local control, or both. In addition, the accurate knowledge of the dose distributions actually delivered will improve the quality of dose-response data. To accomplish our goal, we intend to leverage the advances we made through our IMRT research in the previous two funding cycles.