69 / 881
Total Energy Released per MAss (TERMA)
Radiation is scattered within
the treatment head of the
accelerator.
Dose rate
“
in-air
”
depends
on field size.
T r
r r
( )
( ) ( )
′ = ′
′
μ
ρ
Ψ
Extra-focal radiation
(head scatter)
Secondary source