Real-time PET guided radiation therapy for cancer treatment

描述（由申请人提供）：如果放射剂量可以安全地增加，放射治疗肺癌的有效性可以显著提高。剂量增加的主要限制是治疗期间由于患者呼吸而导致肿瘤位置不确定。除了几何变化外，肿瘤缺氧是治疗失败的主要原因。如果剂量可以上升到耐辐射缺氧区域，那么局部肿瘤控制也将得到改善。RefleXion Medical正在使用正电子发射断层扫描（PET）来指导放射治疗，以便在治疗过程中实时了解肿瘤的几何和生物变化。在项目的第一阶段，我们的目标是：1)开发一种沿着单个PET响应线引导辐射束的方法；2)开发一种利用短时间内发生的PET排放子集估算目标位置的方法；以及3)目标1和目标2中开发的测试方法，使用从移动幻影中获取的列表模式PET数据。目标3实验将在斯坦福癌症中心完成，利用运动幻影和PET-CT系统。在第二阶段，我们计划使用运动幻影和PET检测器桌面系统直接控制多叶准直器，以便通过实验证明肿瘤跟踪。开发的实时pet引导放射治疗方法可以通过安全的剂量递增和对异质性移动肿瘤的最佳剂量分配来显著提高治疗效果。

DESCRIPTION (provided by applicant): The effectiveness of radiation therapy for lung cancer treatment can be significantly improved if radiation dose can be safely escalated. The main limitation to dose escalation is tumor location uncertainty during treatment due to patient respiration. In addition to geometric changes, tumor hypoxia is a leading cause of treatment failure. If dose can be escalated to radioresistant hypoxic regions then local tumor control would also improve. RefleXion Medical is using positron emission tomography (PET) to guide radiation delivery so that both geometric and biological changes in the tumor can be accounted for in real-time during treatment. In Phase I of the project we aim to: 1) Develop a method of directing radiation beam-lets along individual PET lines-of- response; 2) Develop a method of estimating target position using subsets of PET emissions that occur over a short period of time; and 3) Test methods developed in Aims 1 and 2 using list-mode PET data acquired from a moving phantom. Aim 3 experiments will be accomplished at the Stanford Cancer Center utilizing a motion phantom and a PET-CT system. In Phase II we plan to directly control a multi-leaf collimator using a motion phantom and PET detector table-top system so that tumor tracking can be demonstrated experimentally. The developed treatment methods for real-time PET-guided radiation therapy may result in significantly more effective treatments through safe dose escalation and optimal distribution of the dose to the heterogeneous moving tumor. PUBLIC HEALTH RELEVANCE: Lung cancer is the biggest cancer killer in both men and women in the U.S. While two-thirds of U.S cancer patients are treated with radiation therapy, success rates for lung cancer are low, largely due to movement of the tumor during breathing. In this project, RefleXion Medical aims to develop a radiotherapy system that uses positron emission tomography (PET) to non-invasively track a tumor's position and biological state during treatment. Real-time PET-guided radiotherapy will enable safe dose escalation and smarter dose distribution, leading to more effective treatment of tumors that exhibit significant motion.