of normal.
Only the results with monoenergetic-, fission spectrum- and wea-
pon-neutrons delivered acutely were included, for a total of 15 series and
5 different strains of mice.
Inspection of the data makes it immediately ap-
parent that the nature of the dose-relationship is in this case quite different from that observed with x- and gamma-rays.
This impression is confirmed
when the following equations are fitted to the data with the following results
y
=
a+bD
Ro
=
e
y=atbDtiecD
y
=
5.7361 + 0.0851 D
=
0.5751
(10)
y -= 2.005 + 0.1837 D - 277 10° -) D 2
FO 2
=
0.6860
(9)
.
(11)
(12)
Clearly, none of these two relationships provides a satisfactory interpolation
to the neutron data, because the first of them fails to show the initial steep
rise and the latter, after showing a maximum of effect between 300 and 400 rad
bends down rapidly towards lower values, an effect which would be difficult to
interpret.
The following relationship was also fitted
y = atbvbd
(13)
and it yielded the following solution
y
0.1645 + 1.764 VD
=
Re
(14)
0.6837
The square-root relationship seemed to fit the data fairly well in that it described adequately the increase of effect seen at very low doses of neutrons
and the ensuring levelling-off of the data for doses up to 500 rad, along a
slope roughly parallel to the slope of the low-LET radiation dose relationship.
95.
Thus, whatever the actual relationship truly applying to the life-span-
shortening effect caused by neutrons in the mouse, under the conditions of
the present analysis the data are best described by a relationship having a
convex upward trend with dose, such that the efficiency of low neutron doses
is higher than that of higher doses.
The numerical value of this higher effi-