A,
3
OFFICIAL USE ONLY
:
III.
Doses to the Bones
The three principal bone-seeking isotopes of concern are sr70_y™
sr&9, and paogO,
Evaluation of these may be made in terms of
amount deposited in the bones versus maximum permissible body burdens,
“TERT
meMce ”
or in rads of dose that they deliver after deposition.
Since values
for maximm permissible body burdens are based on the concept that these
will be maintained indefinitely in the body, they are not so valid for
gr99 and Ba
140, ralt0 when considering short periods of emergency intake.
The following principal assumptions are used in calculating the
doses to the bones of adults:
a.
The percentages of the isotopes of sr90_y% sr89 and Bal+0
- tat#0 in mixed fission products are according to Hunter and Ballau.?
be.
The percentages of intake of these isotopes that are de-
posited in the bones, the energies of emissions, and their effective
half lives are according to reference five - except for sr7° where 8
27.7 year radiological half life is used here.
c.
The mass of the bones is 7,000 grams.
The method of calculation of doses to the bones is illustrated by
computing the dose from gr89 from the intake of 11 microcuries (See V.
Discussion below) of mixed fission products on the 20th day.
Step 1.
Determine the sr°? to reach the bone.
According to reference four:
The sr9 content in mixed fission products an the 20th day is 54%.
According to reference five:
The intake of Sr29 to reach to the bones is 25%.
OFFICIAL USE ONLY
-6-