Table 1.

Mechanical and geometric accuracy QA tests for image guidance system.

Frequency	QA test	Tolerance
Daily	Imager positioning/repositioning	±1 mm
Imaging and treatment beam coincidence (single gantry angle)	±1 mm
Monthly	Imaging and treatment beam coincidence (4 cardinal gantry angles)	±1 mm
Image scaling	±2 mm
Mechanical alignment – full range of travel	±2 mm
Geometric accuracy for CBCT	±2 mm
Automatic image registration and offset calculation accuracy	±2 mm