With the above digression, we can uow ceturn to Fig. 3.
from the figure that it is
incomplete and misleading to present the data
terms of a “linear-no-threshold”
Fig.
2
It is clear
relationship.
Rather,
as shown also in
the data should be presented as distributions of hit cells,
the
area of the distribution representing the total amount of exposure.
It
then becomes clear
that what ts needed
that will respond quantally is
response curve,
to evaluate
the number of hit cells
the cell equivalent of an organ-dose
1.,¢@., a relationship
that will provide the probability of
a cell quantal response, as a function of iucreasing cell dose.
function,
-
termed a hit-size effectiveness
developed (11-14).
curve In Fig. 2,
in
One such curve
function (HSEF),
Such a
has heen
is shown schematically as
the S-shaped
An actual curve for chromosome abnormalities, derived
From the data in Fig. 1, is shown in Fig. 5.(3).
The use of these curves
is now discussed, following which thetr derivation is summarized.
.
&3
ca
2
1.0
T
T
oF ot
ae:
PROBABILITY OF QUANTAL EFFECT
CH26, CELLS
chromosome abnomalities
0.8}
(Skarsgard}
4
abnormal metaphases
0.6
o 8215p m*
4
O4F
4
0.2 5+
4
chromatid exchange
F = 10.4 pm?
oO
10
20
L
30
ai.
id
50 70 100
iiiJ
y/ kev m'
Fig. 5
Ref.
3}.
1
200 300
An HSEF derived from the data shown in Fig. 1 (from
The two curves are for different chromosome aberrations.
Use of the HSEF
The use of the liSEF is shown schematically in Fig. 2.
For any one or
combination of cell hit size distributions shown, one simply multiplies theja
distribution by the HSEF, ise.,
the number of hit cells at each hit size 1s
multiplied by the corresponding point on the HSEF.
-216-
20129 16
The resulting products egy
r
ai
ne
af,