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Factor-based dose calculations: basic dosimetric quantities
Determination of S
c
in a miniphantom
( )
(
)
(
)
M ;
M ;
ref
p
d cK
dcK
cS
c
=
ref
ref
p
AAPM TG 74 report, Med Phys 36 (11), 2009
If the photon beam spectrum is identical in both situations, then it follows that
S
c
effectively
measures the
energy fluence output ratio.
However, in situations when the beam quality in
c
is different from
c
ref
, it has to be noticed that
the measured signal ratio is only
an estimator
of the energy fluence ratio, biased by the mini-
phantom and spectrum specific variations of collision kerma and attenuation.