Intrafraction Geometric Uncertainties in Frameless Image-Guided Radiosurgery

The estimated margins show the large influence of systematic intrafraction shifts and the capacity of dynamic alignment to correct for them. For dynamic alignment, the margin approximately equates with the traditional precision tolerances for radiosurgery, whereas for fixed alignment, the margin is three times greater. Although these margins may not be directly applicable to radiosurgery planning, they expose the effects of intrafraction motion on target coverage.