.
r
ho
.
.
,
‘
.
‘
1
i.
* a
Ae Eade atic otA a areBERd adelEth atl satanar atalan inatdhns, slfe at
1il
TuHortum-Serres Activities aNb Mran Dost Rares in Vanrots ORGANS
(50 mi THorotrast Ingectep INTRAVASCULARLY)
2
er
eT
TABLE 51.
ee
I
|
ape
ast par.
|
ee
ation.
Organ
orotras:
10s ob. Wile
body
ted pre.
able 48.
Liver
t “best.
Spleen
of the Red bone marrow
lin Ta. Lungs
vailable Blood
P Kidneys
rom the
P Skeleton (marrow-free)
yve, Not
owever,
a
~
||
Wet weight, g|
70,000
| 1, 250
|
TABLE 52.
1,700
150
860
210
1,500
1,000
5, 400
300
7,000
100
10
0
1.3
15
3 in the
ulation.
a]. (36
%. For
activi-
's work
ce that
|
22 ®Ra
228Th
625
625
|
,
430
105
25
5
0
0.3
25
||
22 ‘Ra
|
880
|
300
95
30
3
0
0.6
30
20m
and
26Po
20
3
3
0.5
50
!
|
22Bi.
|
525
|
525
*
_
135
35
|
|
from all
| Rads/year
Isotopes,
—_
——_—
270
67
|
*2Pb
x
530
~
|
‘a -ray dose
|
0
Ly nl
90
25
40
30
55
2
45
|
71
165
40
30
55
4
45
|
18
13
6
3
3
StumMary or Estimatep Dost Rares To ORGans or THOROTRAST PATIENTS
o make
| atoms
as2 Th
|
——
volving
Nanocuries in organ at steady state
Mean organ dose rate > 20 years after 50 ml Thorotrast intravascularly, Rads/year®)
Author
Year
Parr et al. (this
1967
EV vashte
NT hyete
Wale ®
Riindost. 12
) Hlursh et al.
Revnolds et al.C?
1965
1965
1964, 1965
1958
1957
1957
puper)
Liver
Spleen
Redbone
71
168
w
Kidney
|
'
8
|
Lung
Skeleton
Blood
13
3
6
4-9
4-7
65
68
78
145
178
78
|
30
14-61
8
2
1
4-9
'“ Dose rates reported by the different authors in most cases do not refer to 50 ml of Thorotrast. The values quoted here have
been normalized on the assumption of proportionality between dose rates and volume of administered Thorotrast, though this is
not strictly true because of differences in self-absorption of the radiation.
Fthoron concentrations in the blood maybe aproxi-
Witely double those of *!*Pb,
The data of Tables 37, 39, and 50 have been combiicd in Table 51 to give a “balance sheet” for the dis| tibution of activities throughout the whole body. This
table is a slightly revised and recalculated version of
one first prepared by Marinelli for presentation at an
| IAEA panel meeting in October 1965,{38) and since relrodtuced by Dudley.“The activities refer to 50 ml
ThOs agglomerates. The bound fraction in each case
\oiune administered, but is within the range of 10 to
‘inl that was most commonly employed. Mean dose
} tiutex (Rads/year) corresponding to these activities
have been calculated and are recorded in the last col-
RESat late times after Thorotrast administration, the
‘in of Table 51. They take account only of the more
nnportant component of the dose, that deriving from
the «-particles, which is of the order of 90% of the total
Hose, Corrections for self-absorption of the a-particles
jents:
tivity of each nuclide thought to be bound within the
6! Thorotrast administered intravascularly 20-25 years
}1 «viously. Such a dose probably execeds the average
, 48
, 48
where A is the concentration of *3°Th expressed as
dpm/mm*. For the case considered in Table 51, / has
values of 0.46, 0.31, and 0.87 for liver, spleen, and
bone-marrow,respectively, and unity for the other tissues. However, in accordance with the “recoil-escape”
model proposed above, these self-absorption corrections were not applied equally to all the thorium-series
decay products, but only to that fraction of the ac-
he inert ThOs agglomerates have been applied ac-
“Ine to the factor F quoted by Rundo‘*) in the form
F = 0,645 e—1-504 4. 0.355 e—9.0474,
was estimated from the following argument. In the
steady state activity ratio 2*8Ra/**Th = ~0.5 1s interpreted as meaning that the proportion of **%Ra
atoms ejected by recoil from the ThO. agglomerates
is ~50%. If it is then assumed that each subsequent
a-decay within the agglomerates confers approximately
the same 50% probability that the atom concerned will
escape into the surrounding tissue, then the bound
activity of each radionuclide can be readily inferred.
Only to these bound activities have the Rundo selfabsorption corrections been applied. If they had been