ABSTRACT
Imaging systems, such as cone-beam CT or stereoscopic x-ray imaging, that can detect setup errors in six dimensions, three translational and three rotational (yaw, pitch, and roll), are becoming common features on modern linacs. While conventional linac couches allow for setup correction in four dimensions (three translational and yaw rotation), they do not offer the ability to correct for rotational pitch and roll errors. Literature shows that patients can exhibit pitch and roll rotational setup errors of up to 4° (Ahn et al. 2009; Kaiser et al. 2006). Therapists may attempt pitch and roll corrections by physically adjusting the patient, but this is inexact, requires reimaging, and is thus not an efficient solution.
