ASMR 2017

Flattening Filter Free (FFF)

• Not a new concept (1990s) but gained momentum with SRS and SBRT increasing in clinical use

• 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