1268-1269 / 2239
measurement with an ionisation chamber
large perturbation?
( )
(
)
(
)
(
)
(
)
[ ]
A
A
p
S
zAM A,z D
AS
w
ref
ref
w
,
=
=
Small fields: relative dosimetry - field size factor, S
cp
Challenge: perturbation factors
A
: field size (aperture)
z
ref
: reference depth
A
A
ρ
z AM z AD
ref
ref
det
air
ref
ref
ref
ref
w
cp
,
,