Table 1.

Tolerances from TG‐142 and machine specifications for the Varian TrueBeam® for all cone‐beam computed tomography (CBCT) image quality metrics.

Parameter	TG −142	Varian TrueBeam®
Geometric distortion	<2 mm for non‐SRS/SBRT <1 mm for SRS/SBRT	N/A
Spatial resolution (full fan)	Baseline	≥6 lp/mm
Spatial resolution (half fan)	Baseline	≥4 lp/mm
HU uniformity	Baseline	±40 HU
Contrast	Baseline	N/A
Noise	Baseline	N/A
HU accuracy	Baseline	±50 HU