Feasibility and effectiveness of self-made tiltable treatment couch in minimizing setup errors of radiotherapy for thoracic and abdominal tumors

Objective: A self-made tiltable treatment couch was adopted for CT simulation positioning and radiotherapy to evaluate the feasibility and effectiveness to minimize the setup errors. Methods: Twenty-two patients with thoracic and abdominal tumors receiving radiotherapy in Department of Radiation Oncology, Peking Union Medical College between March and September 2016 were recruited in this study. All patients were randomly divided into the experimental (n = 11) and control groups (n = 11). In the study group, the tiltable treatment couch was adopted to switch the patients from the standing position to the supine position, and conventional supine position was utilized in the control group. All patients received CT positioning under spontaneous breathing. Image registration was performed according to the standard recommendations of IGRT group. The image registration data for the translational and rotation errors of CBCT were recorded and analyzed. The setup errors were calculated by four-parameter model between two groups. Results: In the experimental group, the translational error of the x direction was (-0.012 ± 0.128) cm with a variation range of (0.29-0.70 cm), (0.272 ± 0.123) cm for the y direction (0.23-0.70 cm) and (0.089 ± 0.105) cm for the z direction (0.14-0.53 cm), respectively. In the control group, the translational error of the x direction was (0.006 ± 0.198) cm (0.27-0.75 cm), (-0.108 ± 0.396) cm for the y direction (0.56-2.08 cm) and (-0.096 ± 0.176) cm for the z direction (0.34-0.89 cm), respectively. Conclusions: Application of the self-made tiltable treatment couch can enhance the setup reproducibility and reduce the setup errors, especially in the y direction during radiotherapy for the thoracic and abdominal tumors. (authors)