Table 3.
Minimum SBRT relevant equipment QA and tolerances for helical tomotherapy systems
| Frequency | Test | Tolerance |
|---|---|---|
| Daily | Red laser initialization (congruence with green laser) | 1 mm |
| Image/laser coordinate coincidence | 1 mm | |
| Image registration/alignment | 1 mm | |
| Accelerator output constancy (rotational or static) | ±3% | |
| Monthly | Transverse beam profile | 1% average difference in field core |
| Longitudinal beam profile (each slice width) | 1% of slice width FWHM | |
| Output constancy and rotational output variation | ±2% | |
| Beam quality constancy | ±1% PDD10 or TMR20 10 | |
| Red and green laser alignment | 1 mm | |
| Couch positioning accuracy | 1 mm | |
| CT dimensional accuracy | 1 mm | |
| Annually | Couch speed uniformity | ±2% dose nonuniformity |
| Couch translation per gantry rotation | 1 mm per 5 cm | |
| Accelerator output | ±1.5% | |
| Beam quality (each slice width) | ±1% PDD10 or TMR20 10 | |
| Verification of small‐field beam data | ±2% from baseline for >1.0 cm apertures, ±5% from baseline for ≤1.0 cm apertures | |
| CT imaging — treatment — laser coordinate coincidence | 1.0 mm | |
| E2E localization assessment “hidden target test” | 1.0 mm | |
| E2E dosimetric evaluation | ±5% measured vs. calculated |
SRS is not included in the scope of this document for helical tomotherapy.
Tolerances are absolute accuracy, not variation from baseline, unless otherwise stated.