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Factor-based dose calculations basic dosimetric quantities
Phantom scatter factor, S
p
( )
(
)
(
)
(
)
ref
primary
ref
total
p
;
;
;
z s D
zs
D
zs D
sS
=
( )
( ) ( )
s sK s
D
p
p
primary
β
=
(
)
ref
ref
primary
ref
ref
total
;
z s
D
if s = collimator setting c at the plane of the isocentre
( )
( )
cS
cS
c
cp
≅
( )
( )
( )
( )
( )
( )
β
=
β
β
=
p
cp
ref
p
p
ref
p
p
cp
p
c
S
S
c
c
cK
cK
S cS
s: field size
Total scatter factor
Mainly known as
Output factor
AAPM TG 74 report, Med Phys 36 (11), 2009
( )
β
ref
p
c
c
≅
1 under lateral CPE
dose to collision kerma ratio