鼻咽癌调强治疗照射野布野方向对剂量分布的影响

目的:研究不同布野方向对5野鼻咽癌同期增量调强计划剂量分布的影响。方法:取同一病例分别从患者头部上半球、下半球和全球设5个照射野,设计调强治疗计划,分别得出其剂量分布结果,对比靶区及各主要危及器官受量。结果:靶区剂量分布差别不大;全球5野均匀分布照射时,腮腺受量明显少于其他布野方式;从下半球布野视交叉受量最少。结论:不同布野方向对5野鼻咽癌同期增量调强计划靶区剂量分布影响不大,全球5野均匀分布照射可更好地保护腮腺,当靶区距视交叉较近时推荐从下半球布野。

Influence of dose distribution selected from different beam orientation for a nasopharyngeal carcinoma IMRT plan

Purpose:To evaluate the different dose distribution created by three different plans on a nasopharyngeal carcinoma case with simultaneous integrated boost intensity modulated radiation therapy (SIB-IMRT). Methods:we designed three different SIB-IMRT plans on a nasopharyngeal carcinoma case, one was from anterior direction of the head, 5 non-equally spaced fields, another was from posterior direction of the head, 5 non-equally spaced fields also, third was 5 equally spaced fields around the head. Each plan had its dose distribution to the target and main critical structures.Results:No significant difference of dose distribution to the target when comparing the previous three different IMRT plans. However, dose to the parotids delivered from 5-equally spacd was obviously lower than the other plans, dose to the optic chiasm was much lower created by the plan designed from the posterior direction of the head with 5 non-equally spacea field.Conclusions:For a nasopharyngeal carcinoma case, there is no significant difference of dose distribution to the target compared with three different 5-beam orientation SIB-IMRT plans. To protect parotids, we recommend designing a plan with equal beam direction around the head. When the target is very close to the optic chiasm, plauning from posterior direction of the head should be better.