104
TABLE 42.
Batch No.
Eaquitiprium Activity Ratios or THorium DaucutTer Proptcrs In Liver
Animal
|
Code No.
Duration
8Ra/22Th
12878
(2y)@
Man
Man
|
|
02
03
49d
49d
0.30
0.326
—
—
—
1.01
0.59
0.65
-—
ca
_
_
09940
(5-Gy )
Rat
Rat
72
73
36d
38d
0.34
0.38
0.87
0.99
0.65
6.77
0.54
0.51
0.65
0.63
0.7
0.*
13098
(4y)
Rat
Rat
Dog
Man
Man
Rat
_ Rat
Rat
Rat
65
67
78
83
8&5
TH? .
TH3
TH4
TH5
20d
41d
21d
26d
48d
18m
22m
12m
22m
0.25
0.19
0.18
0.20
0.19
0.30@
0.24
0.25
0.21@
1.1
0.98
0.96
-—
—
—
0.94
0.97
0.86
0.87
0.88
0.88
—
—
—
—
0.31
0.38
0.55
0.53
0.59
0.561
0.52
0.51
0.50
1.4
0.37
0.34
—_
0.63
0.54
0.34
0.38
0.41
O.<
0._
_
_
1,(
0.!
Q.+
-
?
Man
?
Weighted
mean
Man
66
166
;
lly
26y
0.36
BAC/28Ra | 28ThRa | 2MRa/8Th
_
m~Q. 402
—
0.27
0.97
1.00
1.01
0.89
_
Pb/*4Ra
22Bi/:
0.75
—_—
—
—
0.53
0.48
0.7
_
() Possibly an overestimate since no account was taken of the small amount of activity which mayhave beenleft absorb
the walls of the Thorotrast ampoule.
>) Approximate time since manufacture, calculated from ?%Ra/?Th ratio.
{) This animal was not typical in that, due to a poor injection, most of the Thorotrast was retained at the site of the inj:
in the tail.
() Calculation based on an assumed 2%Th/?8Ra ratio of 0.9.
(e) Measured by growth of 2%Ra y-activity.
tistically different from zero, but do place an upper
limit on the actual concentrations of these radionu-
clides in blood.
The proportion of *!2Pb in the blood observed at
early times after administration (~23% of the whole-
cases the *8*Th activities, and hence also the **
232Th activity ratios, f,, were not measured dir
but were calculated from Eq. (3) (appendix) usil
9
assumed value for the 7*8Th/2?*8Ra activity ratic
as indicated in the footnotes to the tables. To th:
tent that the assumption regarding fe is in erro
may also be the calculated value of f, be in
body burden at three weeks) seems surprisingly high,
and it 1s difficult to account for the fact that it is
higher after three weeks than after one day and seven
days, respectively. Recent measurements in Vienna on
patients with long-term Thorotrast burdens suggest
the tables. They were calculated using weighting
about 12%. Grillmaier in Germany, for similar patients, has reported values between 1.7% and 23.9%,
remarked, however, that there are some obviou-
that after several years the proportion is reduced to
with a mean of about 8%.@7?
Steady State Activity Ratios of Thorium Daughter
Products in Various Tissues
Steady state activity ratios for various pairs of
daughter products have been calculated from the activity data and are presented in Table 42 for liver, in
Table 43 for spleen, in Table 44 for kidney, in Table
45 for bone, and in Table 46 for various other tissues.
Because of the possibility of a dependence on the
batch of Thorotrast used, the results have, in general,
been grouped according to the batch number. In a few
(probably <10%).
Mean values of the activity ratios are includ
tors of 0.1 for those measurements which were fc
be of inferior accuracy and unity otherwise. It mu
consistencies in the results which cannot be expl:
as arising simply from measurement errors or
species differences (e.g., the ?°Th/**%Ra activits
tios), but which may depend on the batch of T]
trast, its age, and the duration of the burden.
Recoil Model to Account for the Observed Act
Ratios
The high activities of most of the daughter proc
of 222Th in the RES can only be regarded as anom:
unless it is assumed that these nuclides are physi
trapped within the particulate material. Otherw!