应用超全向楔形板概念设计治疗计划  

Application of super-omni wedge concept to conformal radiotherapy treatment planning

作　　者：戴建荣[1] 傅卫华[1] 胡逸民[1] 

机构地区：[1]中国医学科学院中国协和医科大学肿瘤研究所肿瘤医院放射治疗科,北京100021

出　　处：《中华放射肿瘤学杂志》2004年第2期113-116,共4页Chinese Journal of Radiation Oncology

摘　　要：目的　运用超全向楔形板概念 ,结合计划系统优化照射野权重的功能 ,来同时优化照射野权重、楔形板角度和方向。方法　分 5个步骤进行 :第一步是根据超全向楔形板概念 ,在每个照射野方向布置 4个 6 0°楔形板照射野 ,楔形方向分别是“LEFT”、“IN”、“RIGHT”、“OUT” ;第二步是根据每个计划系统优化权重功能的特点 ,定义优化问题 (包括优化的目标函数和约束条件 ) ;第三步是启动优化过程 ;第四步是当优化问题有解 ,并且评价优化结果满意时 ,进到第五步 ,否则回到第二步修改优化条件 ;第五步是将超全向楔形板的照射野变换为全向楔形板的照射野 ,以减少照射野数目 ,继而减少治疗时间。结果　将该方法运用到 1例食管癌和 1例脑瘤。与手工计划相比 ,计划靶区剂量更均匀 ,危及器官受照剂量更低。结论　对于复杂布野情况 ,运用该方法不仅可以提高计划质量 ,而且可以缩短计划设计时间。Objective To describe a method which can optimize beam weight, wedge angle, and wedge orientation simultaneously by combining the super-omni wedge (SOW) concept with the function of beam weight optimization provided by a commercial treatment planning system. Methods A five-step procedure including: Step 1. To set up four 60° nominal wedged beams for each beam direction with the wedge orientations of 'LEFT', 'IN', 'RIGHT', 'OUT', respectively; Step 2. To define an optimization request, including an optimization goal and constraints. We use CMS Focus treatment planning system which allows us to choose 'maximize target dose' or 'minimize critical structure dose' as the optimization goal, and to set minimum target dose, maximum target dose, and maximum average dose of critical structures as constraints. Then the optimization process was launched as step 3; Step 4. To evaluate the plan using isodose distributions and dose-volume histograms. If acceptable, go to Step 5. Otherwise, go back to Step 2 to modify optimization constraints; and Step 5. Transform the SOW beams into the beams of omni wedge so as to reduce the number of to-be-delivered beams. Results This procedure was found being able to demonstrate successfully in two clinical cases: an esophageal carcinoma and a brain tumor. Compared with manually designed plan, the optimized plan showed better dose homogeneity in the targets and better sparing of the critical structures. Conclusions This method described is able to optimize beam weights while working with a treatment planning system. Not only does it improve treatment plans' quality, but also shorten the treatment planning process.

关 键 词：超全向楔形板 权重 放射治疗 剂量分布 

分 类 号：R815[医药卫生—放射医学]