IMRT分野与固定钨门技术在大靶区宫颈癌放疗中的剂量学对比

摘要

目的:比较9野动态调强(9-IMRT)分野(split field)与固定钨门(fixed jaw)技术在大靶区宫颈癌放疗中的剂量学参数、治疗效率,为临床大靶区宫颈癌的计划设计提供参考.方法:选取11例根治性放疗的宫颈癌患者,每例病人分别按照9野均分自动分野及固定钨门这两种方式设计计划,计划A为分野计划,计划B为固定钨门计划.PTV处方剂量为45 Gy/(25 f·1.8 Gy),GTV处方剂量为60 Gy/(25 f·2.4 Gy).给予相同的优化参数,使所有计划均能满足95%的靶区体积达到处方剂量要求.同时比较两种不同技术下计划的靶区平均剂量(Dmean)、均匀性指数(HI)和适应性指数(CI)以及膀胱、直肠、双肾、股骨头的Dmean、体积剂量、脊髓点剂量和机器的MU(Monitor Unit)值等参数.结果:两种方式优化后的计划均能很好的满足临床要求,其中B组计划中双侧股骨头平均照射剂量Dmean、直肠的V40、膀胱的V30等剂量学参数均优于A组计划,差异具有统计学意义(P<0.05);两组计划MU值,B组明显低于A组,差异具有统计学意义(P<0.05).结论:自动分野与固定钨门技术在靶区剂量体积覆盖及危及器官(OAR)保护上差异不大,但是固定钨门技术能够让加速器的多叶光栅(multiple leaf collimator,MLC)行程降低,更低的MU值也意味着较短的治疗时间.%Objective:To compare the 9 field dynamic intensity modulated(9-IMRT)(split field)and tungsten (fixed jaw)fixed gate efficiency and dosimetric parameters in the radiotherapy of large target area cervical carcinoma treatment,reference for clinical target planning of cervical cancer.Methods:There were 11 cases of cervical cancer patients with radical radiotherapy.Each patient was designed in accordance with the 9 field plan A for IMRT split field,plan B for fixed tungsten gate project.The PTV prescription dose was 45 Gy/(25 f·1.8 Gy),and the GTV pre-scription dose was 60 Gy/(25 f·2.4 Gy).Given the same optimization parameters,all the plans can meet the target volume of 95%,and meet the prescription dosage requirements.At the same time to compare two different techniques under A,target B group plan,including the average dose uniformity parameter(HI)and adaptive parameters(CI)and bladder,rectum,kidney,femoral head the average dose,dose volume,spinal cord point dose and machine MU(monitor unit)value parameters.Results:Two kinds of optimized scheme can well meet the clinical requirements.The parame-ters of the B group in bilateral femoral head mean dose of Dmean,V40and V30rectal bladder dosimetry was better than A group,the difference was statistically significant(P<0.05).For MU value,B group was significantly lower than A group,with statistical significance(P<0.05).Conclusion:The distinction between fixed tungsten gate technology and IMRT split field in target dose volume coverage and organs at risk(OAR)protection is similar,but the fixed tungsten door technology can make the accelerator MLC reduce stroke,lower MU values also means shorter treatment time.