Geometric accuracy evaluation of a six-degree-of-freedom (6-DoF) couch with cone beam computed tomography (CBCT) using a phantom and correlation study of the position errors in pelvic tumor radiotherapy.

Background: To assess the position accuracy of the six-degree-of-freedom (6-DoF) couch based on cone beam computed tomography (CBCT) and exploit the correlation of the six degrees errors.

Methods: CT scans of an anthropomorphic phantom and patients were obtained at 3 mm slice thicknesses using a Philips scanner at the head, first supine and prostrate positions. An Eclipse Treatment Planning System was used to create a treatment plan.