铅门跟随技术与铅门固定技术在乳腺癌根治术后调强放疗中的剂量学比较

摘要

目的:研究比较铅门跟随技术(JTT)与铅门固定技术(SJT)在乳腺癌根治术后调强放疗中的剂量学差异.方法:在Eclipse TPS(11.0)上采用AAA算法对40例乳腺癌根治术后患者(含锁骨上区,左侧20例、右侧20例)分别采用两种治疗技术设计放疗计划.在95％体积的计划靶区(PTV)满足处方剂量的前提下,尽量降低危及器官的剂量.比较两组治疗计划的剂量一体积直方图及机器总跳数,评估靶区及危及器官的剂量分布.分别将两组治疗计划用Portal Dosimtry进行剂量验证.结果:两组计划的靶区剂量分布均达到临床处方剂量的要求.PTV最大剂量与平均剂量差异无统计学意义.JTT增加了机器跳数,具有极显著性差异(t=4.18,P＜0.01);JTT动态调强计划中全身的V5、V10,健侧肺Dmean,患侧肺、心脏、肝脏的V5、V10和Dmean,脊髓的Dmean和Dmean的均低于SJT动态调强计划的相应值,差异有统计学意义(t=-11.8～-3.3,P＜0.01);患侧肺、心脏、肝脏的V20、V30、v40差异无统计学意义.结论:乳腺癌根治术后放疗患者采用固定射野动态调强放疗JTT与SJT两种技术,其靶区和危及器官受量均能满足临床治疗要求,而JTT能够更好地降低正常组织和危及器官的低剂量照射.%Objective To analyze the dosimetric difference between jaw tracking technique (JTT) and static jaw technique (SJT) in fixed field dynamic intensity-modulated radiotherapy (IMRT) after radical mastectomy for breast cancer.Methods Using an analytical anisotropic algorithm,we designed the radiotherapy plans for 40 patients who had undergone radical mastectomy for breast cancer (involving the supraclavicular region on the left in 20 cases and on the right in 20 cases) on Eclipse TPS (11.0) with both JTT and SJT.The dose of organs-at-risk was minimized as much as possible while the prescribed dose was maintained in 95％ of the planning target volume (PTV).We analyzed the dose-volume histogram,the total machine unit,and dose distributions in the target areas and organs-at-risk and performed dose verification for the two groups of treatment plans using Portal Dosimtry.Results In the two groups of plans,the dose distribution in the target areas all met the prescribed dose requirement.No significant difference was found between the two groups of plans in the maximum dose (Dimx) or the mean dose (Dmean) of PTV,or the V20,V30,V4o in the ipsilateral lung,heart or liver.Compared with SJT plan,JTT plan significantly increased the machine unit (t=4.18,P＜0.01),lowered the V5 and V10 of the whole body,Dmean of the contralateral lung,and V5,V10,Dmean in the ipsilateral lung,the heart and the liver,and decreased the Dmax and Dmeanof the spinal cord (t=-11.8--3.3,P＜0.01).Conclusion Both JTT and SJT in fixed field dynamic IMRT allow delivery of the prescribed doses in the target areas and maintain the dose limit in the organs-at-risk in patients after radical mastectomy for breast cancer,but JTT can better decrease the radiationdose in the normal tissues and the organs-at-risk.