383 / 1228
dose rate to water at point P(r,
θ)
S
K
air kerma strength
Λ
dose rate constant
G
L
(
r
,
θ
)
geometry function (
line-source approximation
)
g
L
(
r
)
radial dose function
F
(
r
,
θ
)
2D anisotropy function
Rivard, et al.,
Med. Phys.
31, 633-674 (2004)
( , )
D r
θ
0 0
( , )
( , )
( ) ( , )
( , )
K
L
D r
S
G r
g r F r
G r
θ
θ
θ
θ
= Λ