鼻咽癌不同立体加量照射方法临床剂量学比较研究

目的：探讨立体定向放射治疗、三维适形放射治疗和调强放射治疗对鼻咽癌残存病灶加量照射的技术特点和适应症。方法：选择鼻咽病灶有残留，大小形态具有代表性的3例进行研究。1例为小于3cm的类圆形病灶，第二例为大于3cm高度不规则病灶，第三例为大于3cm的相对较规则病灶。分别采用上述三种方法进行加量照射，进行临床剂量学比较。比较指标包括等剂量曲线对靶区的包容情况、剂量体积直方图及参数、剂量均一性指数等。结果：对于直径小于3cm类圆形病灶，SRT治疗90％等剂量线完全包容靶体积，靶区内剂量均一性好。大于3cm高度不规则病灶，对靶体积包容、剂量分布均匀性及对重量器官的保护IMRT最优，3D-CRT稍差，SRT最差。大于3cm相对较规则病灶对靶体积包容、剂量分布均匀性及对重要器官的保护IMRT与3D-CRT相当，SRT最差。结论：对于小于3cm的病灶加量照射首选SRT技术对于大于3cm的高度不规则病灶应首选IMRT，其次为3D-CRT技术，SRT不适合该类病灶的照射。对于大于3cm相对较规则的病灶，IMRT和3D-CRT为首选，SRT也可谨慎应用。

Comparison Study of Clinical Dosemetry of Different Techniques for the Boost Radiation Treatment of Nasopharyngeal Carcinoma

Objective:To study the characteristics of different stereotactic radiotherapy techniques for boost treatment of nasopharyngeal carcinoma and their indications.Methods:3 cases of typical residual lesions of nasopharynx were selected for the study.The lesion of the frist case was similarly round and less 3 cm in diameter,the second case had a highly irregularly shaped lesion more 3 cm,and the third one had a large tumor with comparatively regular shape.They were irradiated with 3 different stereotactic radiotherapy techniques and their clinical dosemetries were compared.The research parameters include the high dose coverage for target volume,Dose Volume Histogram and DVH parameters,and dose homogeneity index.Results:For lesion less 3 cm SRT had perfect dose distribution and target coverage.For lesion more 3 cm and irregular in shape 3D-CRT and IMRT had better dose distribution and target coverage,IMRT was even better,SRT had severe dose inhomogenity for such lesions.For lesions more 3 cm and comparatively regular in shape 3 D-CRT and IMRT also had better dose distribution and target coverage,SRT cannot meet the target coverage and dose distribution demand well.Conclusion:SRT is the best choice of boost treatment modality for lesions less 3 cm.IMRT and 3 D-CRT are more suitable for lesions more 3 cm.