Analysis of setup errors on CBCT - based image guided radiation therapy for body tumors patients
10.3760/cma.j.issn.1004-4221.2012.01.019
- VernacularTitle:基于锥形束CT体部肿瘤图像引导放疗的摆位误差分析
- Author:
Qinhong WU
;
Gaofeng LI
;
Chan WANG
;
Xuenan LI
;
Dan WANG
;
Xiangyan SHA
- Publication Type:Journal Article
- Keywords:
Tomography,X-ray computed,cone beam;
Image guided radiotherapy;
Setup error;
Margin;
Body neoplasms
- From:
Chinese Journal of Radiation Oncology
2012;21(1):68-71
- CountryChina
- Language:Chinese
-
Abstract:
ObjectiveTo evaluate setup errors of image guided radiation therapy (IGRT) for body tumors immbilized with vacuum cushions and localized with final isocenter marked method using kilovoltage cone beam CT (KVCBCT).MethodsA retrospective study has been carried out for 223 patients from March 2009 to April 2011.All patients were immobilized with vacuum cushions and localized with final isocenter marked method in Philips PQS CT or Philips Brilliance CT Big Bore scanner,which were equipped with LAP movable laser systems. The CT images were transferred to a Varian Eclipse workstation for contouring and treatment planning.Before irradiation,a KVCBCT scan was performed and image registration was done on a Varian iX linear accelerator via OBI system.Each set of setup errors in right-left ( RL),superior-inferior (SI),and anterior-posterior (AP) directions were gathered.An independent-samples t-test statistical analysis was conducted with the 758 sets of data using SPSS 16.0.Results The statistical analysis showed that setup errors from the 758 datasets were depicted a Gaussian distribution.The system errors ± random errors in RL,SI and AP were ( -0.5 ±2.8) mm,(0.0±3.0) mm and (0.4±3.4)mm,respectively.Referring to the formula for planning target volume margin calculation,M =2.5Σ + 0.7δ,the margins were calculated as 3.2,2.1 and 3.4 mm,respectively.ConclusionsThe margins derived from this retrospective study have confirmed the premise that the treatment plans were executed in patients with high reliability,thereby created a high sense of confidence for the clinicians.
