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(
)
;
CAX
1
out,
in,
( , ; )
1
, ,HVL 2
( )
( )
I
i A
i
r
i
r
i
D d A
p
r d
rdr
M A M A
Ψ
π
ρ
=
≈
⋅
∑ ∫
x
x
Lateral variation of beam quality
Double exponential, incl. depth parameterization and lateral beam quality
variations (“off-axis softening”) for flattened beams
Laterally constant kernel:
T Nyholm, et al (2006)
Phys. Med. Biol. 51 4111-4118
(
)
, ;
,
1 1
out,
in,
( , ; )
1
, , HVL 2
( )
( )
I J
i j A
i j
i
j
r
i
r
i
D d A
p
r d
rdr
M A M A
J
Ψ
π
ρ
= =
≈
⋅
∑∑ ∫
x
x
Including lateral beam quality shift:
Olofsson et al (2006)
Med Phys 33
, 3418-25