ee ee wees = ees
ee ed
calculations and the great range of the experimental data, the close
apreement is fortuitous,
IV, Conclusion
It must be concluded that because of the dif2iculties in
Finally, the data presented here may be used to estimate the
internel dose rate dus to RaD and its daughters relative to that from
the Rrae@ chain, Pig. 1 (Slide 1}.
The effective aose is given Ly the
product of the average energies of the emitted particles, an RBE of
four fur alpina particles and the fracticnal retention of the nuclides.
For Rab and its daugnters and for Re*”, the retention is one; for Face?
and its da._cters, it is 0.3.23)
Consequently, for a given activity
determining the RaD and RaF conteats of the skeleton, the total
dose-rate therein may be difficult to estimate.
Moreover, because
of the lack of correlation between the RaD and the paee6 concentrations,
the relative dose rates cannot be defined as a funetion of geography.
The statistical uncertainties in any associated epiderioloyicai study
would thereby be increased,‘(38)
Some of the difficulties might be
alleviated if further studies make other correlations apparent.
of each parent nuclide, the ratio of effective dose rates of RaD to
Rae* is 0.5.
Table & (Slide 10) shows the average RaD concentration
of 0.246 pe/g ash is equivalent to a rato concentration of 0.673
pe/g ash.
This is about twice the measured pareo soncentration in cur
senples.
It mast be noted that this vector of 2 is actually @ minimum
sinec these camples include a relatively iarge frection from people
residing in areas with high Fa
22
6 drinking water.
in low-level areas, such as Chicago. (12)
.
Most people live
Consequently, over the whole
country the RaD dose-rate levels are ectually about 5 times those cf
Ra““°.
Acknowledgements
Special thanks are due to Dr. A. J. Finkel and Mr. E. F. Luces,
Jr. for obtaining the majority of the samples and to Dr. J. B. Hursh
for the sets af bone specimens.
Mr. Lucas also kindly supplied much
of the parce deta and his discussions were very tLelpful.
Technical
essistanc. was supplicd by Messieurs F. W. Ilcewicz and R. P. Burke.
fam particularly indebted to Mr. L. D. Marinelli for the many helpful
suggestions and discussions during the preparation of this paper.
Since the dose due to Ra2e" in the body is about equal to thet
of Rae?®
(16) the Rad dose is about 2-1/2 times that of the two Ra
nuclides,
The radiation levely of Ra? may be also compared to tnose of
sr??
If an RBE of 4 is assumed for a]lpha tarticles relative to that
of betas, and the gr? concentration is about 0.5 pe/g asnt7) then
the RaD dose is about 10 times thet due to sr”?
~6-
rhea ee
fe es
:
.
FN hae ReaDEKno vey
TO ale mannwear2A. we
.