TG-40
Monthly

Dosimetry Tolerance
X-Ray Output Constancy 2%
Electron Output Constancy 2%
Backup monitor constancy 2%
X-ray central axis dosimetry parameter (PDD,TAR) constancy 2%
Electron central axis dosimetry parameter constancy (PDD) 2mm at theradepth
X-ray Beam Flatness constancy 2%
Electron Beam Flatness constancy 3%
X-ray and electron symmetry 3%

Mechanical Checks
Light/radiation field coincidence 2mm or 1% on a side*
Gantry/collimator angle indicators 1 degree
Wedge position 2mm (or 2% change in transmission factor)
Tray position 2mm
Applicator position 2mm
Field size indicators 2mm
Cross hair centering 2mm
Treatment couch position indicators 2mm/1deg
Latching of wedges/blocking tray Functional
Jaw symmetry 2mm
Field light intensity Functional