千伏极CBCT在食管癌调强放疗摆位中的应用

目的探讨图像引导放疗（IGRT）系统在食管癌调强放疗摆位修正的应用。方法应用医科达公司的synergy机载KV-CBCT对23例食管癌调强患者每次照射前获取x线容积图像（X-ray volumetric images，XVI）与计划CT图像及其靶中心进行匹配，获取x、y、z三个方向的误差，并分析纠正误差。结果23例患者均坚持完成放疗，共做了474次CBCT，其中治疗前320次，摆位误差在X（左右）Y（头脚）Z（前后）三个方向≥3mm，分别为（-0．04±4．63）、（0．07±9．69）、（-0．15±4．33）mm。结论千伏极CBCT在食管癌调强放疗摆位中可以提高等中心摆位精度，检测并调整摆位误差，有效减少放射野边界，减少并发症的发生。

Objective This study was to evaluate the role of kilo-volt cone-beam computed tomography （ KV-CBCT ） in guiding the positioning of Imrt for EPC. Methods From April 2010 to October 2011, 23 EPC patients were treated with the newly installed Elekta-synergy system and they had reviewed KV-CBCT before radiotherapy. The acquired X-ray volumetric image （ XVI ） were co-registered with the planning CT and errors of iso-center positions on x, y and z axes were obtained and analyzed and online set-up correction. Results 22 patients received a total of 474KV-CBCT scans. There were the 320 scans before couch correction. The overall setup errors in x （ left-to-right ） , y （ superior-to-inferior ） and z （ anterior-to-posterior ） directions of〉3mm were （ -0.04 ± 4.63 ） , （ 0.07 ± 6.69 ） , （ -0.15 ± 4.33 ） mm. Conclusion KV CBCT image-guided radiotherapy may improve the setup precision of IMAG for EPC and may guide optimal PTV designing.