GLOFIL-125
GLOFIL-125- iothalamate sodium, i-125 injection
QOL Medical
DESCRIPTION
General
GLOFIL® -125 (Sodium Iothalamate I-125 Injection) is a sterile, nonpyrogenic aqueous injection containing approximately 1 mg sodium iothalamate per mL, and 0.9 percent benzyl alcohol as a preservative. The radioactive concentration of the material is 250-300 μCi/mL as of the calibration date. Sodium bicarbonate and hydrochloric acid are present for pH adjustment.
Physical Characteristics
Iodine-125 decays by electron capture with a physical half-life of 60.14 days. Photons that are useful for detection are listed in Table 1.
| ||
Radiation | Mean Number Per Disintegration | Mean Energy (keV) |
Gamma-1 | 0.067 | 35.5 |
Kα1 X-ray | 0.741 | 27.5 |
Kα2 X-ray | 0.398 | 27.2 |
Kß1 X-ray | 0.140 | 31.0 |
Kß2 X-ray | 0.043 | 31.7 |
Kß3 X-ray | 0.072 | 30.9 |
The specific gamma ray constant for I-125 is 1.43 R/mCi-hr at 1 cm. The first half value thickness of lead (Pb) for I-125 is 0.017 mm. A range of values for the relative attenuation of the radiation emitted by this radionuclide resulting from interposition of various thicknesses of Pb is shown in Table 2. For example, the use of 0.28 mm of Pb will decrease the external radiation exposure by a factor of 10,000.
| |
Shield Thickness (Pb), mm | Coefficient of Attenuation |
0.017 | 0.5 |
0.058 | 0.1 |
0.12 | 0.01 |
0.2 | 0.001 |
0.28 | 0.0001 |
To correct for physical decay of this radionuclide, the fractions that remain at selected time intervals after the date of calibration are shown in Table 3.
| |||||
Days | Fraction Remaining | Days | Fraction Remaining | Days | Fraction Remaining |
0* | 1.000 | 15 | 0.841 | 30 | 0.707 |
1 | 0.989 | 16 | 0.831 | 31 | 0.699 |
2 | 0.977 | 17 | 0.822 | 32 | 0.691 |
3 | 0.966 | 18 | 0.812 | 33 | 0.683 |
4 | 0.955 | 19 | 0.803 | 34 | 0.675 |
5 | 0.944 | 20 | 0.794 | 35 | 0.667 |
6 | 0.933 | 21 | 0.785 | 36 | 0.660 |
7 | 0.922 | 22 | 0.776 | 37 | 0.652 |
8 | 0.912 | 23 | 0.767 | 38 | 0.645 |
9 | 0.901 | 24 | 0.758 | 39 | 0.637 |
10 | 0.891 | 25 | 0.749 | 40 | 0.630 |
11 | 0.881 | 26 | 0.740 | 41 | 0.623 |
12 | 0.871 | 27 | 0.732 | 42 | 0.616 |
13 | 0.861 | 28 | 0.724 | 43 | 0.608 |
14 | 0.851 | 29 | 0.715 | 44 | 0.601 |
45 | 0.595 |
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