Set-up error of CR in total body irradiation localization and lung shielding

Objective: To investigate the set-up error of CR in total body irradiation localization and lung shielding. Methods: TOR 18FG software was employed to measure the image quality of images at kV and MV levels. The clinical processes were established and the positioning error was analyzed. Results: The low contrast resolution and spatial resolution of MV level images were much worse than those at kV level in the condition of total body irradiation, but the image at MV level could be used to identify the high contrast tissues and employed in total body irradiation. The longitudinal errors were (0.50±1.65) cm for left lung and (1.16±1.56) cm for right lung in AP direction, while (1.12±2.22) cm and (0.41±2.16) cm respectively in PA direction. The errors of lateral were (0.81±1.19) cm for left lung and (0.43±1.20) cm for right lung in AP direction, while (0.31±1.64) cm and (0.55±1.49) cm respectively in PA direction. Conclusions: Application of CR in total body irradiation could make positioning in treatment much easily and reduce the localization errors. (authors)