Table 4.

An example of the stereotactic beam isocentricity assessment for the 6MV FFF beam; mean and one standard deviation of the beam offset (BO) collimated by the Aktina Cone, the ball‐bearing offset (BBO) and the beam CAX deviations from the BB phantom (beam isocentricity ‐ BI) in radial and transverse directions averaged over all gantry and collimator angles.

6MV FFF	BO (mm)	BBO (mm)	BI (mm)
Radial (Mean ± 1SD)	−0.09 ± 0.08	0.39 ± 0.56	0.48 ± 0.50
Transverse (Mean ± 1SD)	−0.06 ± 0.14	0.01 ± 0.29	0.07 ± 0.30