摘要
目的研究不同射野角度的鼻咽癌调强放疗靶区和周围正常组织、危及器官的计划剂量学分布的差异。方法选择11例鼻咽癌患者行调强放疗,每例患者按照相同的处方剂量要求在治疗计划系统中设计3套计划:7野均匀分布为A计划(每野角度间隔51°);前7野为B计划(每野角度间隔42°);非共面7野为C计划(其中共面5野均分,每野间隔72°,非共面2野床角90°,机架角330°及30°)。计划均采用相同的处方剂量条件进行优化,比较3组计划靶区和危及器官的剂量分布、剂量体积直方图(DVH)、靶区适形度指数(CI)、平均剂量Dmean、最小剂量、最大剂量等参数。结果 3组计划靶区的剂量分布基本相同。对于脑干、脊髓所接受的D1剂量,3组计划之间差别较小,均在耐受剂量范围以内,B计划稍大于A计划、C计划。颞叶D33的剂量A计划比B计划、C计划分别降低9.28%、12.38%。对于颞颌关节、腮腺等并行器官所接受的D50剂量,C计划分别低于A计划、B计划,颞颌关节C计划分别比A计划、B计划降低30.47%、33.29%。口腔黏膜的受照平均剂量,C计划分别比A计划、B计划增加10.49%和10.85%。结论鼻咽癌7野调强放疗可以满足靶区的剂量需求,设计个体化的最优调强放疗计划时,应考虑肿瘤体积的大小和生长部位,选择合适的设野和优化条件,有望获得较好的剂量分布,且可明显降低正常组织并发症的发生率。
Objective To compare different beam arrangements in 7-field intensity-modulated radiation therapy（IMRT） to treat na- sopharyngeal carcinoma by analyzing doses delivered to target tissue and adjacent normal tissue. Methods A total of 12 patients with nasopharyngeal carcinoma who had been prescribed the same total IMRT dose were treated with one of the following three IMRT plans ： average plan,with a beam angle interval of 51° ; anterior plan, with a beam angle interval of 42° ; and a non-eoplanar plan, involving 5 co-planar fields with a beam angle interval of 72° ,as well as 2 non-eoplanar fields with a couch angle of 90° and gantry angles of 30° and 330°. All plans were optimized using the same constraints to ensure comparability of the results.The following out- comes were measured：dose distribution to the planned target volume（PTV） and to organs at risk, dose volume histogram, PTV confor- mity index,mean dose（Dmean）,minimum dose,and maximum dose（Dmax）. Results The three IMRT plans provided similar dose distributions to the PTV.The anterior plan provided a slightly higher Dmax-l%（D1） to the spinal cord and brain stem than did the other plans,but this difference was very small and within the range of tolerated doses.The average plan provided a temporal lobe dose D33 that was 9.28% smaller than that of the anterior plan and 12.38% smaller than that of the non-coplanar plan.The non-coplanar plan provided a lower D50 to the parotid gland and temporomandibular joint than did the other plans, and the non-coplanar plan provided a temporomandibular joint dose D50 that was 30.47% smaller than that of the average plan and 33.29% smaller than that of the anterior plan.The non-eoplanar plan provided an oral mucosa Dmean that was 10.49% higher than that of the average plan and 10.85% higher than that of the anterior plan. Conclusion Satisfactory dose coverage in the nasopharyngeal carcinoma target volume was achieved using 7-field IMRT.By designing individualized IMRT plans based on the locatio
出处
《中国癌症防治杂志》
CAS
2013年第2期134-138,共5页
CHINESE JOURNAL OF ONCOLOGY PREVENTION AND TREATMENT
基金
广东省佛山市卫生局科研基金资助项目(2011064)
关键词
鼻咽肿瘤
射野角度
调强放疗
剂量分布
Nasopharyngeal neoplasms
Beam angle
Intensity-modulated radiation therapy
Bose distribution
