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Flattening Filter Free (FFF)
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Not a new concept (1990s) but gained momentum with SRS
and SBRT increasing in clinical use
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Rationale and
Theoretical
Benefits
Increase dose rate (300-600) to 1400-2400
Decreased beam on time (consider even more when combined with
VMAT)
Improve efficiency
Patient comfort and stability
Intrafraction motion
Particularly attractive for treatments with high dose per fraction or
respiratory motion management (eg DIBH)
Lower leaf leakage and out of field dose
Possibly offset by an increase in MUs compared to FF beams