TG-142
Linac Daily QA
Dosimetry
Output constancy (X-ray & electron)
Mechanical
Laser localization
ODI (Optical distance indicator) @iso
Collimator size indicator
Safety
Door interlock
Audiovisual monitor
Door closing safety
Radiation area monitor (if used)
Beam on indicator
Stereotactic interlocks
Imaging
Collision interlocks
Positioning/repositioning
Imaging & tx coordinate coincidence
Tolerance
3%
2 mm (1.5mm IMRT & 1mm stereo)
2 mm
2mm (1mm stereo)
Functional yes/no
Functional yes/no
Functional yes/no
Functional yes/no
Functional yes/no
Functional yes/no
Functional yes/no
2mm (1mm CBCT & stereo)
2mm (1mm stereo)
Linac Monthly QA
Dosimetry
Output constancy (X-ray & electron)
Backup counter constancy
Dose rate output constancy (IMRT/SBRT)
Beam profile constancy, photon & electron
Beam energy constancy, electron
Mechanical
Light/radiation field coincidence (symmetric)
Light/radiation field coincidence (asymmetric)
Distance check device for lasers versus front pointer
Gantry & collimator angle indicators
Wedge position
Tray position
Compensator position
Jaw position indicators (symmetric)
Jaw position indicators (asymmetric)
Cross-hair centering
Treatment couch position indicators
Latching, wedges & blocking tray
Laser localization
Safety
Laser guard-interlock
Respiratory gating
Beam output constancy
Phase, amplitude beam control
Respiratory monitoring system
Gating interlock
Imaging
Imaging & tx coordinate coincidence (4 cardinal angles)
Tolerance
2%
2%
2%
1%
2% / 2mm
2 mm or 1% on a side
1 mm or 1% on a side
1 mm
1o
2 mm
2 mm
2 mm
2 mm
1 mm
1 mm
2 mm/1o (1mm/0.5o stereo)
Functional yes/no
±2mm (±1mm IMRT; <±1mm stereo)
Functional yes/no
2%
Functional yes/no
Functional yes/no
Functional yes/no
2mm (1mm stereo)
TG-142
Scaling
Spatial resolution, contrast, HU constancy, uniformity & noise
Geometric distortion, CBCT
2mm (1mm kV stereo)
Baseline
2mm (1mm stereo)
Linac Annual QA
Dosimetry
Flatness change from baseline, photon & electron
Symmetry change from baseline, photon & electron
SRS rotation mode, MU set vs delivered
SRS rotation mode, gantry arc set vs delivered
Output calibration (X-ray & electron) (TG-51)
X-ray output constancy dependence on field size
Electron output constancy dependence on applicator
Beam quality, photon (PDD, TMR)
Beam quality, electron (R50)
Transmission factor constancy for all accessories (eg wedges)
Monitor unit linearity, photon & electron
Output constancy vs dose rate, photon
Output constancy vs. gantry angle (x-ray & electron)
Off-axis factor constancy vs. gantry angle, photon & electron
Arc mode (expected MU, degrees)
TBI/TSET mode
PDD/TMR & OAF constancy
TBI/TSET output calibration
TBI/TSET accessories
Mechanical
Rotation isocenter (Collimator, gantry, & couch)
Electron applicator interlocks
Isocenter coincidence of radiation and mechanical
Tabletop sag
Table angle
Table travel max range all directions
Stereotactic accessories & lockouts
Safety
Manufacturer test procedures
Respiratory gating
Beam energy constancy
Temporal accuracy of phase/amplitude gate on
Calibration of surrogate for respiratory phase/amplitude
Interlock testing
Imaging
Full range of travel SDD (EPID)
Imaging dose, beam quality/energy
Tolerance
1%
±1%
1.0 MU or 2% (whichever is greater)
1.0o or 2% (whichever is greater)
±1% (absolute)
2%@<4x4cm2; 1%@≥4x4cm2
±2% from baseline
±1% from baseline
±1mm from baseline
±2%
±2%@≥5MU; ±5%@2-4MU
±2% from baseline
±1% from baseline
±1% from baseline
±1% from baseline
Functional yes/no
1% (TBI) or 1mm PDD shift (TSET)
2% from baseline
2% from baseline
±1mm from baseline
Functional yes/no
±2mm (±1mm stereo) from baseline
2 mm
1o
±2 mm
Functional yes/no
Functional yes/no
2%
100 ms of expected
100 ms of expected
Functional yes/no
±5mm
Baseline
1. Klein EE, Hanley J, Bayouth J et al. Task group 142 report: quality assurance of medical accelerators.
Med Phys. 2009;36(9):4197-4212. http://dx.doi.org/10.1118/1.3190392
TG-142
CT Simulator
Daily
Gantry laser alignment with center of imaging
plane
CT number accuracy
Image noise
In plane spatial integrity
Monthly
Orientation of lasers and tabletop with imaging
plane
Spacing of lateral wall lasers w/ respect to lateral
gantry lasers and scan plane
Vertical and longitudinal table motion
CT number accuracy
In plane spatial integrity
Field uniformity
Annually
Table indexing & position
Gantry tilt accuracy
Gantry tilt position accuracy
Scan localization
Radiation profile width
Sensitivity profile width (semiannual)
CT number accuracy
Field uniformity
Electron density to CT number conversion
Spatial and contrast resolution
Tolerance
+/- 2mm
0 +/-5HU (water)
Manufacture specs
+/- 1mm X or Y axis
+/- 2mm over length of laser
+/- 2mm
+/- 1mm
0 +/-5HU (water) (4 to 5 different materials)
+/- 1mm X and Y axis
+/- 5HU for most common kVp
+/- 1mm over scan range
+/- 1mm over gantry range
+/- 1o or +/- 1mm
+/- 1mm
Manufacturer specs
+/- 1mm
Electron density phantom
+/- 5HU for all kVp
Consistent with commissioning and test phantom
manufacturer specs
Manufacturer specs
1. Mutic S, Palta J, Butker E, et al. Quality assurance for computed-tomography simulators and the
computed-tomography-simulation process: report of the AAPM radiation therapy committee
task group no. 66. Med. Phys. 2003;30(10): 2762-2791
QA Brachytherapy
Equipment /Source
Applicator
Radioactive Sources
Remote Afterloader
Frequency
Procedure
Initial use
Inspected & radiographed before initial use
Annually (@time of inventory)
Inspection
Before initial use & semiannually
3 years
Leak Testing
Prior to every treatment
Mechanical damage, ease of coupling,
kinks, mechanical deformation, transfer
tube
Cesium source leak testing
TG-142
@Time of source change
Source Calibration
Monthly
Source positioning accuracy
Source activity
Mechanical damage, ease of coupling,
kinks, mechanical deformation, transfer
tube
Timer
Power failure test
Treatment planning
Prior to patient treatment
Target coverage
Homogeneity of dose
Dose prescription
Normal structure doses
Consistency
Duration
Independent dose check
Treatment Planning System
Frequency
Before Treatment
Weekly
Procedure
Tolerance
Measurement of beam data
+/-3%
Measurement of patient specific data
+/-3%
Inaccuracies of data entry
+/-2mm
Inaccuracies of data output
+/-2mm
Monthly
Algorithm inaccuracy
+/-2mm or +/-2%
Yearly
Algorithm inaccuracy
+/-2mm or +/-2%
Vann, A.M. Quality Assurance of TPS, IMRT,SRS. SoftChalk. La Crosse, WI:UW-L Medical
Dosimetry Program; 2015.