particle cellistons,
exposure Increases,
for a cidtation of a de fined quality.
neither
the ean nor
the maximum of
Note
that increases.
Note also
represents a graded serles of cell doses.
function of
the HSEF,
that provides
the cell dose,
the
distribution,
the
Tf
cesult will be
tie nunber of
that each distribution
Also shown is the S-shaped
curve, an HSEF (hit-sitze effectiveness function),
discussed above
the
the distrtbutious
chanuyes--it is only the area undec the distributions, fi.e.,
exposed cells hit,
that as
the relationship
probability of a quantal response as 4
the cell dose distribution is multiplied by
the correspondingly marked smaller
under the larger one.
The area under
the smaller
distrLbution provides the single and determining end point in quantitative
epidemflology or
i.@.,
risk assessment related
the fraction of
to single cell-initiated endpoints,
those cells exposed during a piven exposure that will
respond quantally.
What has been referred tu above as a "cell phantom" actually is much
more
than the cell analogue of an organ phantom.
determine a dose
to a single cell,
Rather than simply
it provides not only
the
risk that a
cell will he dosed and that dose will be of a given size, but also, with
the HSEF,
response.
the probability
that that douse will result in a quantal
Thus the phantom might more appropriately be called a “cell risk
metec", racher than a "microdosimeter"™.
Now that the basic outlines of the proposed approach have been put
rorth,
the necessary more detailed information on each element of
the
overall approach can be provided,
Dose Confused with Exposure
Be
c
lu order to explaln and extend the above title and statements, it is
BM
pr
useful first to demonstrate the relationship between the absorbed dose to
“Sig
"
the organ system and
that
to
the cellular elements of
that system.
This
te.
can he done as follows:
pe
wh
(that
4
‘
E
\
--taf=
4
f
\
Zz
-N
[Phe TUT).
He are, ¢
ny
/
tox
Uv
'
{
i
E
the
o
-t
*z2 is desipnated 2
hit
cells
in ICRU publications
only.
~210-
90424912
to specify
that the mean is
to
ae
re].
@
ind:
-_