eR.
~
Op
*
©
cons WM Va a
93
nent of Hyperthyroidism
Table 6-1
Decay Characteristics of '?°I*
Radiation
Photons
Energy (kev)
Gamma
6.66
35.4
Kai X-ray
27.4
76.15
Kg, X-ray
30.9
20.56
Kyo x-ray
27.2
39.06
Keo X-ray
31.8
K int. conv.
L int. conv.
M int. conv.
3.6
30.9
34.6
80.0
11.42
1.9
KLL Auger
KLX Auger
22.6
26.4
14.16
5.97
L x-rays
Electrons
N/100 Disintegrations
KXY Auger
LMN Auger
MXY Auger
4.26
3.7
22.26
30.1
0.96
2.9
154.42
0.8
364.61 }
A, = 0.0151
A; = 0.0107
_
A, = 0.0159
*Half-life: 60.2 days.
result in more marked effects on the site of hormonogenesis than on the replicative
capacity. Studies comparing the effects of "I and '*5] in animal systems have
demonstrated recovery of function after initial suppression by '*I. A more marked
effect was seen on iodine-concentrating mechanisms than on goitrogenesis,>***°
and histopathological studies have confirmed the localization of dose.*®
The cell survival studies of Greig et al.5’ are confirmatory. Only the work of
Jongejan and Van Putten® indicates an opposite conclusion. They found no difference in the }*°I/*'I ratio for administered levels of activity to produceidentical
Fig. 6-2. Schematic representation of percentage distribution of electron radiation
dose inside thyroid cell. The radiations ema-
nate from '*5] in the follicular colloid. (Reproduced with permission from Lewitus Z. et al.,
Seminars in Nucl. Med. /:411-421, 1972.)
er
4X
La
ao
SSO,
lOw —————»|
\
4
effects on hormonal function and on cell killing.
J ISOA
96%
4%