Evaluation of the clinical usefulness for using verification images during frameless radiosurgery.

Our previous studies showed that intrafraction motion needs to be corrected for in frameless radiosurgery. This study was designed to evaluate if verification images can correct for mechanical inaccuracy and intrafraction motion. With proper immobilization and verification images on a regular basis during treatment, mechanical (table-) inaccuracies and intrafraction motion can be corrected for and the absence of PTV-margins warranted.