Table 1.
Quality control tests for medical linear accelerators (tolerances and action levels are specified in millimeters unless otherwise stated)
| Designator | Test | Performance | |
|---|---|---|---|
| Tolerance | Action | ||
| Daily | |||
| DL1 | Door interlock/last person out | Functional | |
| DL2 | Motion interlock | Functional | |
| DL3 | Couch brakes | Functional | |
| DL4 | Beam status indicators | Functional | |
| DL5 | Patient audiovisual monitors | Functional | |
| DL6 | Room radiation monitors | Functional | |
| DL7 | Beam interrupt/counters | Functional | |
| DL8 | Lasers/crosswires | 1 | 2 |
| DL9 | Optical distance indicator | 1 | 2 |
| DL10 | Optical back pointer | 2 | 3 |
| DL11 | Field size indicator | 1 | 2 |
| DL12 | Output constancy—photons | 2% | 3% |
| DL13 | Dynamic wedge factors | 1% | 2% |
| DL14 | Output constancy—electrons | 2% | 3% |
| Monthly | |||
| ML1 | Emergency off | Functional | |
| ML2 | Wedge, tray cone interlocks | Functional | |
| ML3 | Accessories integrity and centering | Functional | |
| ML4 | Gantry angle readouts | 0.5° | 1° |
| ML5 | Collimator angle readouts | 0.5° | 1° |
| ML6 | Couch position readouts | 1 | 2 |
| ML7 | Couch isocenter | 1 | 2 |
| ML8 | Couch angle | 0.5° | 1° |
| ML9 | Optical distance indicator | 1 | 2 |
| ML10 | Crosswire centering | 1 | 2 |
| ML11 | Light/radiation coincidence | 1 | 2 |
| ML12 | Field size indicator | 1 | 2 |
| ML13 | Relative dosimetry | 1% | 2% |
| ML14 | Central axis depth dose reproducibility | 1 (2%) | 2 (3%) |
| ML15 | Beam flatness | 2% | 3% |
| ML16 | Beam symmetry | 2% | 3% |
| ML17 | Records | Complete | |
| Annually | |||
| AL1 | Reference dosimetry—TG51 | 1% | 2% |
| AL2 | Relative output factor reproducibility | 1% | 2% |
| AL3 | Wedge transmission factor reproducibility | 1% | 2% |
| AL4 | Accessory transmission factor reproducibility | 1% | 2% |
| AL5 | Output reproducibility vs. gantry angle | 1% | 2% |
| AL6 | Beam symmetry reproducibility vs. gantry angle | 2% | 3% |
| AL7 | Monitor chamber linearity | 1% | 2% |
| AL8 | End monitor effect | 0.1 MU | 0.2 MU |
| AL9 | Collimator rotation isocenter | 1 | 2 |
| AL10 | Gantry rotation isocenter | 1 | 2 |
| AL11 | Couch rotation isocenter | 1 | 2 |
| AL12 | Coincidence of collimator, gantry, couch axes | 1 | 2 |
| AL13 | Coincidence of isocenters | 1 | 2 |
| AL14 | Couch deflection | 3 | 5 |
| AL15 | Independent quality control review | Complete | |