Evaluation of the Interchangeability of Cone Beam Computed Tomography and Catalyst for Patient Positioning in Radiotherapy for Head and Neck Cancer Patients

This study aims to evaluate the interchangeability between cone beam computed tomography (CBCT) and the optical surface scanning system (Catalyst) for daily positioning during radiation therapy in head and neck cancer patients. This study was designed as a prospective observational descriptive study divided into two parts. The first part involved a phantom study using the computerized imaging reference systems (CIRS) child atom phantom. It aimed to detect deviations in patient position across six degrees of freedom (lateral, longitudinal, vertical, rotation, roll, and pitch) using the optical light scanner and Catalyst and compare them with deviations detected by CBCT in the same treatment sessions. The second part included 252 sessions, during which 30 head and neck cancer patients were treated at Children Cancer Hospital 57357, Egypt, using both Catalyst and CBCT for setup treatment positioning. The differences between CBCT and Catalyst in all six degrees of deviation were not statistically significant (lateral (P = 0.175), longitudinal (P = 0.296), vertical (P = 0.110), rotation (P = 0.936), roll (P = 0.527), and pitch (P = 0.270)). The optical light scanner system Catalyst is comparable to CBCT. Surface scanning (Catalyst) has proven reliable and feasible for daily patient positioning, with the advantage of avoiding daily exposure to additional radiation.