Real-time intrafraction 3D spine tracking using gantry-mounted kV imaging for single fraction high dose functional radiosurgery

Background

Spinal nerve root ablation of 70-90 Gy with single fraction stereotactic radiosurgery (SRS) delivered in short partial arcs (30-60 degrees) is an emerging treatment for managing chronic thoracoabdominal wall pain. The proximity of the target to spinal cord and the high per fraction dose demand intrafraction motion monitoring with sub-millimeter accuracy. Pre-treatment cone-beam CT (CBCT) and intermittent room-mounted triggered kV imaging do not provide continuous internal anatomical verification during beam delivery. Gantry-mounted real-time tracking solutions have been mostly validated for full arc stereotactic body radiation therapy (SBRT) at substantially lower doses.