调强放疗过程中解剖结构改变导致剂量变化的研究  

Study of dosimetric variations introduced by anatomic changes during intensity-modulated radiotherapy

作　　者：张达光[1,2] 杨成文[1,2] 蒋胜鹏 王佩国[1,2] 王伟 

机构地区：[1]天津医科大学肿瘤医院,国家肿瘤临床医学研究中心,300060 [2]天津市肿瘤防治重点实验室

出　　处：《国际生物医学工程杂志》2013年第6期340-343,共4页International Journal of Biomedical Engineering

摘　　要：目的 分析调强放疗过程中头颈肿瘤患者解剖结构的改变和由此导致的剂量分布变化,探讨疗程中重新设计治疗计划的必要性.方法 对21例接受调强放疗的鼻咽癌患者在治疗过程中重新行CT扫描,借助变形配准软件在获得的CT图上重新勾画出靶区和危及器官;并计算治疗计划在新CT图像上的剂量分布结果,分析靶区和危及器官的体积和剂量变化.结果 患者头颈部外轮廓的体积和靶区显在瘤区（GTVnd）的体积均明显减小,脊髓、脑干的体积没有显著变化,左右腮腺的体积大幅减小,变化率分别为（-24.23±12.15）％和（-25.82±10.46）％（P＜0.05）.鼻咽大体肿瘤计划靶区（PGTVnx）的D95％和Dmean指数没有明显改变,脊髓和脑干的D1cc指数均升高,变化率分别为（8.12±10.32）％和（14.60±18.85）％;左右腮腺的平均剂量显著升高了（27.43±17.67）％和（26.76±12.46）％ （P＜0.05）.结论 头颈肿瘤调强放疗过程中患者解剖结构的变化会导致脊髓、脑干和腮腺的实际剂量与原计划产生明显偏差,在疗程中重新设计治疗计划有临床意义,有助于保证靶区剂量充足和危及器官的剂量安全.Objective To analyze the anatomic changes and dosimetric variations of patients with head-and-neck cancer during intensity-modulated radiotherapy and to assess the necessity of re-planning the treatment course.Methods Twenty-one nasopharyngeal carcinoma patients were selected to receive the second CT scan in the course of intensity-modulated radiotherapy,targets and organs at risk were re-contoured on the new CT images with the help of deformable registration software.Actual dose distribution delivered by the original treatment plan was calculated on the second CT image,and then the volume and doses of targets and organs at risk were compared between the planning CT and second CT.Results The volume of patient＇s head-and-neck outlines and GTVnd decreased significantly,the volume of cord and brainstem didn＇t change much,while the volume of left and right parotids decreased significantly by （24.23 ± 12.15）％ and （25.82± 10.46）％,respectively.The parameters D95％ and Dmean of PGTVnx kept stable,but the parameters D1cc of spinal cord PRV and brainstem PRV increased by （8.12± 10.32）％ and （14.60±18.85）％ respectively.The mean dose of the left and right parotids increased significantly by （27.43±17.67）％ and （26.76±12.46）％,respectively.Conclusion The anatomical changes of patients undergoing intensity-modulated radiotherapy will cause significant dosimetric variations of the cord,brainstem and parotids,so it＇s meaningful and necessary to re-design the treatment plan in the course of radiotherapy.Repeat CT imaging and replanning during the course of IMRT is essential to ensure adequate doses to target volumes and safe doses to normal tissue.

关 键 词：调强放疗 头颈肿瘤 剂量变化 计划设计 

分 类 号：R739.91[医药卫生—肿瘤] R730.55[医药卫生—临床医学]