755 / 1542
•
Higher DR
→
Dosimetric equipment (dose rate dependence?– P
ion
-k
q
-partial volume)
→
Radiobiology of HDR? No correction factor recommended
→
Main advantage FFF for
SRT (high fraction dose-small fields–
no modulation)
→
Motion management
– reduced treatment time (but interplay?)
Dosimetric characteristics
→
Clinical implications
•
Softer spectrum-low energies not removed
→
Lower effective energy if the electron beam is the same (shallower D
max
)
→
Higher skin dose
→
But purer spectrum (+ < e
-
contamination) and easier to model
→
Reduced variation of energy spectrum across field size (due to different hardening in
the field)
•
Reduced head scatter
→
Reduced treatment head leakage
→
Reduced variation of output ratio in air with field size
→
Lower out of field dose to surrounding tissues
(Kragl et al. Z Med Phys 2011;21)
•
Less neutron dose
(less photon fluence/dose and no neutron generated in the FF)
→
use of higher energy photons?