X线双能减影技术在肺癌调强适形放疗靶区勾画中的应用

Clinical Application of Dual Energy Subtraction Chest Radiography in Delineating Targets of Intensity Modulated Radiation Therapy for Lung Cancer

目的探讨利用X线双能减影检测肿块活动度对肺癌调强适形放疗(IMRT)靶区勾画的指导价值。方法利用X线双能减影技术对44例肺癌患者进行肿块活动度检测,以任意方向上活动度3mm为界限,分为减影组12例和门控组32例。两组患者实体肿瘤靶区(GTV)勾画后,向各个方向外扩6mm为计划靶区(PTV)。所有患者在投照前进行锥形束CT(CBCT)精度验证和配准,统计两组肿块活动度以及配准时PTV轮廓覆盖肿块的程度。放疗结束后随访,并观察近期疗效和不良反应。结果患者肺部肿块在头脚(Z)方向的活动程度大于左右(X)和腹背(Y)方向(P<0.05或P<0.01);X方向上,患者不同部位肺肿块活动程度相对一致(P>0.05);门控组患者各方向轴上肿块活动程度均显著小于减影组(P<0.05);经CBCT精度验证,多数患者(减影组83.3%;门控组90.6%)肿块边缘距离PTV轮廓的最小距离≥4mm;患者放疗有效率为77.3%,无Ⅲ级以上放射性肺炎。结论肺癌患者IMRT前,利用X线双能减影技术进行个体化肿块活动度检测对靶区勾画具有潜在的指导意义,值得临床借鉴。

Objective To evaluate the application of dual energy subtraction chest radiography technique for detection of tumor movement,in order to guide delineation of target for intensity modulated radiation therapy（IMRT）.Methods Movement of tumor in 44 patients with lung cancer was measured by using dual energy subtraction initially.Patients were then divided into subtraction（movement3mm at any direction）and respiratory gating group（movement≥3 mm at any direction）,with 12 and 32patients respectively.Planning target volume（PTV）was defined 6mm outside the gross tumor volume（GTV）in all directions.Measurement verification were performed by cone beam CT（CBCT）in all patients,tumor movement and PTV profile coverage were observed.After treatment,patients were followed-up to evaluate the short-term outcome and related side-effects.Results Movement range in direction of head-feet（Z）was significantly larger than those in direction of left-right（X）and abdomen-back（Y）（P〈0.05 or P〈0.01）;there was no significant difference in tumor movement among different directions（P〈0.05）;range of tumor movement at all direction in respiratory gating group was significantly smaller than in subtraction group（P〈0.05）;distance between tumor margin and PTV profile was≥4mm in most of patients,with 83.3%in subtraction group and 90.6%in respiratory gating group.Conclusion Detection the range of tumor movement by dual energy subtraction chest radiography has potential in guiding target delineation for IMRT.