MU/min
Monitor Units delivered per minute — linac dose rate. Standard tiers:
- 600 MU/min — flattened-beam clinical default (Clinac iX standard).
- 800 MU/min — SRS-mode flattened beams.
- 1200–2400 MU/min — flattening-filter-free (FFF) beams on TrueBeam / Versa HD class.
Why it matters to buyers: Higher dose rate reduces treatment time per fraction. SRS / SBRT high-dose-per-fraction protocols need higher rates to keep delivery time clinically reasonable. FFF is the load-bearing feature for short-duration single-fraction deliveries.
Why it matters to engineers: Dose-rate calibration is part of TG-142 annual QA. VMAT requires synchronized control of dose rate, MLC position, and gantry speed; drift in any of the three is a fail.