A1,
A2,
B,
C1,
C2,
D,
E,
F,
G-H,
I-K,
L,
M,
N,
O,
P1,
P2,
Q-R,
S,
T,
U-V,
W-Z
Thallium Online, Description, Chemistry, Ingredients - Thallous Chloride
Thallium Online, Description, Chemistry, Ingredients - Thallous Chloride
DESCRIPTION
Thallous Chloride Tl 201 Injection is supplied in isotonic
solution as a sterile, non-pyrogenic diagnostic radiopharmaceutical for
intravenous administration. The aqueous solution at the time of calibration
contains 74MBq/ml (2mCi/ml) Thallous Chloride Tl 201. The pH is adjusted
with hydrochloric acid and/or sodium hydroxide solution.It is made isotonic
with 9mg/ml sodium chloride and is preserved with 9mg/ml benzyl alcohol.
Thallium Tl 201 is cyclotron produced with no carrier added
and contains no less than 98% Thallium Tl 201 as a percentage of total activity
with contaminants less than 0.3% Thallium Tl 200, 1.2% Thallium Tl 202, and
0.2% Lead Pb 203 expressed as a percentage of Tl 201 Injection activity at calibration.
It is recommended that Thallous Chloride Tl 201 Injection be
administered close to calibration time to minimize the effect of higher levels
of radionuclide contaminants pre-andpostcalibration.Theconcen-tration of each
radionuclide contaminant changes with time.
Physical Characteristics Thallium Tl 201, with a physical half-life of 73.1
hours, decays by electron capture to Mercury Hg 201.1 Photons that
are useful for detection and imaging are listed in Table 1. The lower energy
X-rays obtained from the Mercury Hg 201 daughter of Tl 201 are recommended for
myocardial imaging, because the mean %/disintegration at 68-80.3 KeV is much
greater than the combination of gamma-4 a n d g a m m a - 6 m e a n %/disintegration.
Table 1.Principal Radiation Emission Data
|
Radiation
|
Mean %/Disintegration
|
Mean Energy (KeV)
|
|
Gamma-4
|
2.7
|
135.3
|
|
Gamma-6
|
10.0
|
167.4
|
|
Mercury X-rays
|
94.4
|
68-80.3
|
|
1Martin, M.J., Nuclear Data Project, ORNL, January 1977.
|
EXTERNAL RADIATION
The specific gamma ray constant for Thallium Tl 201 is 33 micro-coulombs/Kg-MBq-hr
(4.7R/mCi-hr.) at 1cm.The first half-value layer is 0.0006cm of lead. A range
of values for the relative attenuation of the r adiation emitted by this radionuclide
that results from the interposition of various thicknesses of lead (Pb) is shown
in Table 2. For example, the use of 0.21cm of lead will decrease the external
radiation exposure by a factor of about 1,000.
Table 2.Radiation Attenuation by Lead Shielding2
|
cm of Lead (Pb)
|
Coefficient of Attenuation
|
|
0.0006
|
0.5
|
|
0.015
|
10-1
|
|
0.098
|
10-2
|
|
0.21
|
10-3
|
|
0.33
|
10-4
|
| |
|
|
2Kocher, David C., "Radioactive Decay Data Tables,"DOE/TIC-11026,
181 (1981)
|
Table 3.Thallium TI 201 Decay Chart;Half-Life 73.1 Hours
|
Hours
|
Fraction
Remaining
|
Hours
|
Fraction
Remaining
|
Hours
|
Fraction
Remaining
|
|
0*
|
1.00
|
42
|
0.67
|
84
|
0.45
|
|
6
|
0.95
|
48
|
0.63
|
90
|
0.43
|
|
12
|
0.89
|
54
|
0.60
|
96
|
0.40
|
|
18
|
0.84
|
60
|
0.57
|
108
|
0.36
|
|
24
|
0.80
|
66
|
0.54
|
120
|
0.32
|
|
30
|
0.75
|
72
|
0.51
|
132
|
0.29
|
|
36
|
0.71
|
78
|
0.48
|
144
|
0.26
|
|
*Calibration Time
|
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