FRACTION, F, OF NUCLEI! ABLE TO ESCAPE (%)
108
100
R
d= diameter
R= recoil range
he: d/R
d = thickness
fe d/R
R = recoil range
2
4
6
8
10
i2
14
IS
p= (PARTICLE SIZE/RECOIL RANGE)
Fic. 85.—-Theoretical escape of recoiling atoms from spherical and planar particles
TABLE 48.
Tissue
Author
Liver
Reference
| Duration, years|
™8Ra/2Th
28Th/28Ra
24Ra /28Th
22Ph /24Ra
tundo
2
13.5-14.5
Hursh
Baserga
34
35
20
15
0.62 (2)
[0.62-0.625]
0.76 (2)
[0.73-0.80]
0.66 (2)
[0.66-0.67]
0.42 (2)
[0.39-0. 45]
0.46 (1)
0.90 (3)
(0. 87-0. 92]
—
—
Kaul
! Parr et al.
|
Spleen
{undo
Hursh
Kaul
Parr et al.
Trabecular
bone
Marinelli et
without marrow |
al.
, Kaul
Parr et al.
Red bone marrow
Sreapy-State Activrry Ratios 1n Man (BURDENS 1 YEAR)
Kaul
an et al.
6, 7
| This paper
long term (?)
—
0.41 (1)
11-26
0.36 (1)
13.5-14.5
0.69 (1)
6,7
long term (?)
This paper
11-26
0.72 (3)
[(0.33-1.07]
0.36 (1)
2
34
11
6, 7
| This paper
6, 7
This paper
20
15-26.5
long term (?)
26
long term (?)
- 11-26
0.48 (1)
1.6 (1)
1.3 (3)
[1.2-1.5]
—
0.23 (3)
f0.19-G.30]
_
0.9 (1)
0.88 (1)
—
—
—_—
—
1.00 (2)
0.75 (1)
—-
0.83 (1)
0.75 (1)
0.17 (1)
0.91 (4)
[0.85-0.96]
1.00 (2)
{0.97-1.03]
0.90 (3)
(0.89-0.91}
0.74 (1)
1.09 (7)
—
—
1.2 (7)
{1.1-1.7]
1.0 (1)
—
1.0 (1)
7 (1)
—
1.12 (3)
[1.08-1.18]
1.05 (2)
1.0-1.1
—
—
0.59 (2)
[0. 58-0. 60]
—
[1.00-1.01] -
0.96 (1)
(0. 64-1. 48]
—
|?!
—
0.57 (3) |
[0.44-0.84] |
—
() Figures in — parentheses quote the number of measurements. Figures in square parentheses quote the range.
viously places this nuclide on a very sensitive part of
the curve. Perhaps this accounts for some of the vari-
ability in results obtained with different batches of
Thorotrast. It is also significant that at late times after
Thorotrast administration, the particles are present in
the form of aggregates, and the escape of **8Ra appears
to be further impeded. Thus, steady state activity ratios, ““8Ra/**?Th, of the order of 0.5 are then reported
(see Table 48). Presumably this higher retenti
be explained by the recoil of 7 8Ra atoms from o:
ticle into another in such a way that they cont:
be trapped.
The interpretation of the estimated 2?°TI
steady state activity ratios, fe, presents consi:
difficulties (see appendix). From the results of
term experiments, the calculated values of (1 —
peal
fy)
roet
1
rr