鼻咽癌调强放疗中的摆位误差

Set-up Error in Intensity Modulated Radiotherapy for Nasopharyngeal Carcinoma

[目的]用电子射野图像器件(EPID)拍摄的射野片研究调强放疗治疗鼻咽癌过程中的摆位误差。[方法]比较8例接受调强放疗的初治鼻咽癌患者的数字重建影像(DRR)和EPID图像,得到各个骨性标志间各个方向的偏差,分别以左右、前后和头脚方向上的最大偏差代表该方向的摆位误差。[结果]3个方向的摆位误差范围是-5mm到5.5mm,平均值是(-0.87±1.3)mm,(-0.28±1.5)mm和(-0.55±1.6)mm,大于2mm的误差分别占17.3%、14.3%和17.3%,且各次治疗的摆位误差之间无显著性差异。[结论]鼻咽癌调强放疗的误差在可以接受的范围,而且各次治疗间也没有显著差异,首次治疗时拍摄射野片验证是非常重要的。

[Purpose]To investigate the set-up error in intensity modulated radiotherapy （LMRT）with electric portal image device （EPID）in nasopharyngeal carcinoma（NPC）.[Methods]Diserepancies of bone an atomy markers in various directions were achieved by comparison of digifally reconstructed radiograph（DRR）with image of EPID in 8 cases of NPC initial treated with IMRT.The maxium discrepancies in mediolateral,antero-posterior and cranio-caudal directions were defined as the set-up error of each direction.[Results]The range of setup error in three directions was -5mm to 5.5mm.The mean set-up error in three directions was （-0.87±1.3）mm,（-0.28±1.5）mm and （-0.55±1.6）mm respectively,and errors larger than 2mm accounted for 17.3%,14.3%and 17.3% respectively.No significant difference was found in set-up error among each fraction ations.[Conclusion]The set-up error in IMRT for NPC is acceptable,and also no significant difference in every fractionations.Portal verified image in the first treatment is very important.