利用DVH图分析鼻咽癌调强放疗中正常器官体积剂量的变化

DVH analysis of the change of normal organs volume and dose in intensity modulated radiotherapy for nasopharyngeal carcinoma

目的:应用剂量体积直方图(DVH),研究鼻咽癌患者在放疗过程中正常器官体积及剂量的变化。方法:接受全程调强放疗(IMRT)的20例初治鼻咽癌患者,在治疗20次时,按原固定体位和参考坐标重新CT扫描,设计计划,与原计划进行比较DVH图中正常器官(眼球、晶状体、视神经、腮腺、脊髓及脑干)体积剂量的变化。结果:DVH2上左右腮腺体积明显小于DVH1(P<0.05),左右腮腺和脊髓的最大剂量和平均剂量明显增加,脑干最大剂量变化有统计学意义(P=0.011),其中腮腺的剂量增加与放疗所致的腮腺缩小程度有一定相关性,其余无统计意义。结论:鼻咽癌IMRT过程中正常器官(特别是腮腺)体积剂量会发生一些变化,建议放疗中后期有必要重新勾画靶区,重新计划,减小正常器官的受照量,减少放疗反应。

Objective：To study the change of the normal organs volume and dose in intensity modulated radiotherapy for nasopharyngeal carcinoma with dose-volume histogram（DVH）.Methods：Twenty patients with nasopharyngeal carcinoma were treated by intensity modulated radiotherapy（IMRT）,CT-simulated image was rebuilded with the same body position and reference coordinate at the twentieth time during radiotherapy.The data obtained with DVH were analyzed on the normal organs（eyeballs,bilateral lens,optic nerves,parotid glands,spinal cord and brain stem） during, before and the twentieth treatment.Results：The volume of DVH2 about the left and right parotids were much less compared with DVH1（P〈0.05）.The maximum and mean dose of parotid glands and spinal cord increased obviously,there was statistical significance on the maximum dose of brain stem（P=0.011）,the parotids＇ dose augmented correlated with the shrunken degree of parotids,and other normal organs had no difference.Conclusion：There were some changes of the normal organs volume and dose in IMRT for nasopharyngeal carcinoma,especially for parotid glands.It was requisite to rebuild CT-simulated image and renew plan during midanaphase treatment to reduce radiate dosage and avoid radiotherapy reaction.