Dose Course 2018_Flipping book
Small fields: relative dosimetry - field size factor, S cp
measurement with an ionisation chamber fluence perturbation
A
w
(
)
(
)
) S z AM zAM ref , ρ ref
A,z D ref
,
A A p det
( )
w
AS =
=
cp
(
)
(
z AD
,
ref
w
ref
ref
ref
air
A
ref
Challenge: perturbation factors
A : field size (aperture) z ref : reference depth
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