EPID在颈、胸上段食管癌调强放疗中的应用价值

目的研究电子射野影像系统（EPID）在头颈肩面罩固定下颈、胸上段食管癌调强放疗中的效果。方法放疗前先采集定位片图像为参照,与治疗过程中实时采集的验证图像对比,测量摆位误差。结果入组30例患者共进行了120次治疗重复摆位,采集验证片120张比较每次摆位的体位误差。X轴（左右方向）3 mm以内误差有29例（96.67%）,3~5 mm误差有1例（3.33%）;Y轴（头足方向）3 mm以内误差有28例（93.33%）,3~5 mm误差有2例（6.67%）;Z轴（前后方向）3 mm以内误差有27例（90%）,3~5 mm误差有3例（10%）;X轴、Y轴、Z轴3个方向误差超过5 mm者未发现,我们对误差在3~5 mm患者进行重新摆位验证。结论利用电子射野影像系统可以有效减少放疗摆位误差,提高摆位的准确性,是质量控制和质量保证的有力工具。

The Application Value of EPID in Intensity-Modulated Radiotherapy for Neck and Upper Thoracic Esophageal Cancer

Objective To study the efficacy of electronic portal imaging device（EPID） in intensity-modulated radiotherapy for neck and upper thoracic esophageal cancer,in which the patients were immobilized with the head/neck shoulder immobilization system.Methods The positioning images were collected before radiotherapy as reference images,which then can be compared to the verify images collected from real time,measuring set-up error.Results 30 patients enrolled a total of 120 times of repeated positioning during the treatments.120 verify films were collected.The set-up errors were analyzed by comparing the films of each positioning.X-axis（left and right direction） within 3 mm error is 29 patients（96.67%）,3~5 mm error,1 patient（3.33%）;Y-axis（head foot direction） within 3 mm error,28 patients（93.33%）,3~5 mm error,2 patients（6.67%）;Z axis（anterior-posterior direction） within 3 mm error,27 patients（90%）,3~5 mm error in 3 patients（10%）;no set-up error over 5mm was found in X axis,Y axis,and Z axis,re-positioning verification were made on positioning error over 3~5 mm.Conclusion The electronic portal imaging system,a powerful tool for quality control and quality assurance,it can effectively reduce the radiation set-up error and improve the positioning accuracy.