利用0.13cc电离室对头颈部肿瘤调强放疗计划的剂量学验证

目的:利用0.13cc电离室对头颈部肿瘤调强适形放射治疗(IMRT)计划进行剂量学验证.方法:将20例头颈部肿瘤患者的IMRT计划分别移植到经过CT扫描的调强体模,生成验证计划,将0.13cc电离室放置到调强体模中在加速器下执行验证计划,在治疗计划系统中算出电离室所在区域的吸收剂量为计划剂量,按验证计划照射测量到的电离室吸收剂量为实测剂量,将二者进行比较得出误差.相对误差=(计划剂量-实测剂量)/实测剂量.百分误差超过±5％,说明计划在执行中剂量误差过大,计划需要修正.结果:20例患者中有17例患者验证的误差在±5％以内,表明计划通过；有3例患者误差超过±5％以内,计划需重新修改,计划通过率为85％.结论:剂量学验证确定IMRT治疗剂量的置信度,保证治疗计划的准确实施,提供了临床评价治疗计划的依据.

Dosimetric verification of intensity-modulated radiation therapy in head and neck cancer by 0.13cc ionization chamber

Objective: To use 0.13cc ionization chamber for dosimetry verification of intensity modulated radiation in head and neck cancer.Methods: All 20 patients were treated with intensity modulated radiation therapy,used theirs IMRT plans transferred to phantom scanned by CT,and then generate quality assurance plan(QA plan),ionization chamber area dose calculated in TPS was plan dose,while the dose measured by ionization chamber according to QA plan was actual dose,compare plan dose and actual dose then get the error relative error=(plan dose-actual dose)/actual dose error more than ±5% indicates that there is a big dose error when IMRT plan is performed.Results: Of 20 patients IMRT plans 17 patients plans calculation passed.The other three patients’ plans failed.The pass rate was 85%.Conclusion: In order to determine the confidence of IMRT plan dose,dosimetric verification is necessary,it can ensure that plan accuracy,provide the basis for clinical evaluation of treatment palns.