This research examines the accuracy of The Phantom Laboratory RSVP Phantom™ II with a jaw system that replicates patient biting. The research study examines the positional reproducibility as applicable for radiation oncology patients receiving stereotactic treatment. A bite tray was seated and locked into the phantom jaw system. Infrared passive fiducial array markers were attached to the bite tray. A head band containing a fiducial array was fit around the phantom skull. Ceiling mounted infrared cameras monitoring fiducial locations were used to calculate the spatial position of the bite tray relative to the stationary head band, as the bite tray was repeatedly removed, reinserted, and locked. For 100 sample mounts, the RSVP Phantom™ II jaw system proved to replicate the desired position with an average accuracy of 0.012 ± 0.001 mm and with a maximum difference of only 0.303 ± 0.001 mm. The innovation of the RSVP Phantom II jaw system is ideally suited for stereotactic radiosurgery and radiotherapy for commissioning and quality assurance.