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目的:研究鼻咽癌根治性放疗采用正向调强计划的方法和规律。方法:总结2005年3月～2010年8月共92例鼻咽癌患者行根治性调强放疗的计划设计方案,均采用基于轮廓优化技术,根据靶体积和危及器官预设不同射束的主野形状,手工补野,正向优化设计完成调强计划。结果:剂量分布及剂量体积直方图满足临床要求,PGTVnx(92/92)的D95≥70 Gy,PTV1(85/92)的D95≥60 Gy,PTV2(82/92)的D95≥54 Gy,脊髓最大剂量≤45 Gy(90/92);子野数29～65,平均值39,中位数41;总跳数586.9～1 050.7,平均值720.5,中位数758.6;2006年10月之后的65例患者单次治疗时间为11.6～23.5 min,平均值15.7 min,中位数16.5 min。结论:调强放疗技术给鼻咽癌的放疗带来了全新的解决方案和理念,基于轮廓正向优化技术运用得当可以得到与逆向优化相当的剂量分布,并且有效地降低了总跳数和治疗时间,提高了治疗效率。
Objective: To study the method and regularity of the positive intensity modulation plan for radical radiotherapy of nasopharyngeal carcinoma. METHODS: A total of 92 patients with nasopharyngeal carcinoma who underwent radical intensity modulated radiation therapy from March 2005 to August 2010 were included in the plan design. All of them were based on contour optimization techniques, and different beams were pre-set according to the target volume and organ risk. Wild shape, manual repair field, positive optimization design to complete the strength adjustment plan. Results: Dose distribution and dose volume histograms met clinical requirements, D95 ≥ 70 Gy for PGTVnx (92/92), D95 ≥ 60 Gy for PTV1 (85/92), D95 ≥ 54 Gy for PTV2 (82/92), spinal cord Maximum dose ≤ 45 Gy (90/92); number of subfields 29 to 65, mean 39, median 41; total hops 586.9 to 1050.7, mean 720.5, median 758.6; after October 2006 The 65 patients had a single treatment time of 11.6 to 23.5 minutes with an average of 15.7 minutes and a median of 16.5 minutes. Conclusion: IMRT has brought new solutions and ideas for radiotherapy of nasopharyngeal carcinoma. Based on proper use of contour forward optimization techniques, a dose distribution equivalent to that of reverse optimization can be obtained, and the total number of hops and treatment can be effectively reduced. Time improves treatment efficiency.