Collaborative Research: Optimization of Intensity Modulated Radiation Therapy with Time Varying Delivery Plans and Fraction Constraints

合作研究：随时间变化的递送计划和分数约束优化调强放射治疗

• 批准号: 0813896
• 负责人: Ronald Rardin
• 金额: $ 12.12万
• 依托单位: University of Arkansas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-10-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0813896&HistoricalAwards=false
• 关键词: Collaborative; Research; Optimization; Intensity; Modulated

Radiation therapy is prescribed for over half of cancer cases. Modern intensity modulated radiotherapy (IMRT) uses multiple non-homogeneous beams to tailor the dose distribution delivered over 30-60 daily sessions called fractions. Fractionation exploits relative differences in the sensitivities of tumor and normal tissues to the dose per session. This research extends IMRT planning methods which optimize only over constraints on dose accumulated over the entire treatment, to include also desired limits on dose per fraction. The challenge is to do this in a computationally efficient way given planning over one entire period already taxes modern optimization tools. The strategy is to divide treatment into a series of epochs of identical fractions. Methods will either compute all plans assuming static conditions or step through epochs with a rolling horizon that can incorporate changing circumstances and beam angle sets.Each one percent rise in tumor dose can improve local control by about 1.5 percent, potentially offering meaningful gains to thousands of patients if organ tolerance limits can be satisfied. An obstacle is satisfying rules on total dose and dose per fraction simultaneously. Substantial dose shortfalls in tumor or violations of fraction size limits can appear if plans are optimized with respect only to cumulative dose and then evenly divided into daily sessions. Time varying solutions are required to meet fractionation constraints and respond to changing conditions over the treatment course. Success with time-varying optimization opens the door to emerging methods of image guided radiotherapy recording changes in tissue geometry throughout the treatment course.

超过一半的癌症病例需要接受放射治疗。 现代调强放射治疗 (IMRT) 使用多个非均匀射束来定制每天 30-60 次疗程（称为分数）的剂量分布。 分级利用了肿瘤组织和正常组织对每次治疗剂量的敏感性的相对差异。这项研究扩展了 IMRT 计划方法，该方法仅针对整个治疗过程中累积剂量的限制进行优化，还包括对每部分剂量的所需限制。鉴于整个时期的规划已经对现代优化工具造成了负担，因此挑战在于以一种计算有效的方式做到这一点。 该策略是将治疗分为一系列相同分数的时期。 方法将计算假设静态条件下的所有计划，或者逐步通过滚动地平线的历元，其中可以包含不断变化的环境和射束角度设置。肿瘤剂量每增加 1% 就可以改善约 1.5% 的局部控制，如果能够满足器官耐受极限，则可能为数千名患者带来有意义的收益。一个障碍是同时满足总剂量和每部分剂量的规则。 如果仅针对累积剂量优化计划，然后均匀地划分为每日疗程，则可能会出现肿瘤的严重剂量不足或违反分次大小限制。 需要随时间变化的解决方案以满足分馏限制并响应治疗过程中不断变化的条件。 时变优化的成功为图像引导放射治疗记录整个治疗过程中组织几何形状变化的新兴方法打开了大门。