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Radial differentiation of measured dose for (equivalent) circular fields
2
r
z
6 MV
(
)
( )
meas
1
,
,
2
D
p r z
r z
r dr
=
C Ceberg, et al (1996)
Med Phys 23
, 505-11.
Dashed line :MC
Solid line: from measurements
pencil kernel determination:
(
)
(
) (
)
( )
2
constant
cylindrical
Field
0 0
within
geometry
field radius
integrator
, ,
,
,
, d d
,
d d
r
p
p
D x y z
x y
x x y y z x y
r z r r
=
− −
=
( )
,
p
r z
Absolute normalization is a problem, can be circumvented by phantom scatter normalized measured
dose, and do renormalization via a reference field size of the calculated dose
since