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ESTRO IMRT course 2015
Dose Calculation in Static and Rotational IMRT
Brussels October 8th, 2015
-31-
Kernel-based methods:
Rectilinear density rescaling of the kernel
s
r
‘Rectilinear’ rescaling with the
mean
relative density
along the path
between s and r:
( )
( )
∫
′
′
−
=
s
r
water
rel
s sd
s r
sr
ρ
ρ
ρ
1
,
(
)
(
)
)
() ,( ,
) ,(
)(
, ,
2
s r sr
E h sr
r
srEh
rel
water
rel
water
− ⋅
⋅
⋅
=
ρ
ρ
ρ
ρ
→
The point kernel dose
is dependent on
location
inside of inhomogeneous media
(patient!)
→
efficient numerical dose calculation w.
fast fourier transform not possible without
further approximations
this would be the
kernel dose in a
homogeneous
medium: h
water
!
…and after
rectilinear
rescaling
adapted from Woo and
Cunningham 1990
(Med. Phys. 17(2))