Real-time PET guided radiation therapy for cancer treatment

描述(申请人提供)：如果放射剂量能够安全地增加，肺癌放射治疗的有效性可以显著提高。剂量增加的主要限制是患者呼吸导致的治疗过程中肿瘤位置的不确定性。除了几何形状的改变，肿瘤缺氧是治疗失败的主要原因。如果剂量能够升级到耐辐射的低氧区域，那么局部肿瘤控制也将得到改善。Reflexion医疗公司正在使用正电子发射断层扫描(PET)来指导放射治疗，以便在治疗期间实时计算肿瘤的几何和生物变化。在该项目的第一阶段，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)开发一种使用短时间内发生的PET发射的子集来估计目标位置的方法；以及3)使用从移动模体获取的列表模式PET数据来开发AIMS 1和2中开发的测试方法。目的3个实验将在斯坦福癌症中心利用运动模体和PET-CT系统完成。在第二阶段，我们计划使用运动体模和PET探测器桌面系统直接控制多叶准直器，以便在实验中演示肿瘤跟踪。开发的用于实时PET引导的放射治疗的治疗方法可能会通过安全的剂量递增和将剂量最佳地分配到异质移动的肿瘤来导致显著更有效的治疗。 与公共健康相关：肺癌是美国男性和女性的最大癌症杀手。虽然三分之二的美国癌症患者接受放射治疗，但肺癌的成功率很低，这主要是由于肿瘤在呼吸过程中移动。在这个项目中，Reflexion医疗公司的目标是开发一种放射治疗系统，该系统使用正电子发射断层扫描(PET)来非侵入性地跟踪治疗过程中肿瘤的位置和生物状态。实时PET引导的放射治疗将实现安全的剂量递增和更智能的剂量分布，从而对表现出显著运动的肿瘤进行更有效的治疗。

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.