利用源皮距验证食管癌放疗摆位误差可行性的探讨

Study of feasibility of verifying positioning error for patients with esophageal carcinoma by observing patients′SSD

目的:利用源皮距验证多点固定摆位精度可行性。方法:使用常规模拟机和加速器对25食管例放疗前、中时期所拍摄射野图像与计划系统生成的射野数字重建(DRR)图像进行配准比较,并对病人摆位时机架角源皮距(GSSD)偏差进行了测量。结果:系统误差:G0°SSD为(1.80±1.3)mm、G45°SSD为(2.04±1.3)mm、G315°SSD为(2.10±2.3)mm;随机误差:距离为G0°SSD为(2.53±1.7)mm、G45°SSD为(2.41±2.3)mm、G315°SSD为(2.33±3.0)mm。结论:源皮距验证技术只是提供放疗技师在线摆位验证。快捷、参考方法,而不是放疗摆位验证的可靠方法。

Objective： To verify feasibility of multipoint setup by observing patients＇ sourceskin distance （SSD） .Method： Films of 25 patients with esophageal cancer were obtained by common simulator prophase and metaphase of radiotherapy, and their corresponding digitally reconstructed radiograph （DRR） were snapshot from Treatment plan system （TPS）, then they were matched and compared respectively and patients＇ SSD errors of different gantry angles were measured. Results： The systematic SSD errors were （ 1. 80± 1.3） mm, （ 2.04 ± 1.3） mm, （2.10 ± 2.3） man, and the random SSD errors were （2.53 ± 1.7） mm, （2.41 ± 2.3） mm, （2.33 ± 3.0） mm for gantry angle was 0°, 45°, 315°, respectively. Conclusions： Technology of observing SSD is just a convenient and referred method of on - line positioning verification, but not an exclusive method for radiation therapists.