Day-to-Day Reproducibility of Prostate Intrafraction Motion Assessed by Multiple kV and MV Imaging of Implanted Markers During Treatment

For a large subgroup of patients, the systematic component of intrafraction prostate motion was substantial. Intrafraction motion correction prior to each beam delivery or offline corrections could likely be beneficial for the subgroup of patients with significant motion. The systematic component is well predicted by measurements in the initial fractions.