Indium In 111 Chloride Solution

Indium In 111 is cyclotron produced by the proton irradiation ((p,2n) reaction) of cadmium Cd 112 enriched target. At time of calibration, it contains not less than 99.925% indium In 111 and, not more than 0.075% indium In 114m and zinc Zn 65 combined. At the time of expiration, it contains not less than 99.85% indium 111 and not more than 0.15% indium In 114m and zinc Zn 65 combined. No carrier has been added.

At the time of calibration, the Indium In 111 Chloride Sterile Solution contains not less than 95% of the Indium present as ionic In3+.

Indium In 111 Chloride Sterile Solution is tested for the following metallic impurities: copper, iron, cadmium, lead, zinc, nickel, and mercury, and contains extremely low levels of these metals. The sum of the individual impurity ratios for the metals listed is not more than 0.60 ppm.

Indium In 111 decays by electron capture to cadmium Cd 111 (stable) with a physical half-life of 67.32 hours (2.81 days) (see Table 2)1. Photons useful for detection and imaging are listed in Table 1.

1

From Radiopharmaceutical Internal Dosimetry Information Center, Oak Ridge Associated Universities, Oak Ridge, TN 37831-0117, February 1985.

The exposure rate constant for 37 MBq (1 mCi) of Indium In 111 is 8.3 x 10-4 C/kg/hr (3.21 R/hr) at 1 cm. The specific gamma ray constant for Indium In 111 is 3.21 R/hr-mCi @ 1 cm1. The first half-value thickness of lead (Pb) is 0.023 cm. A range of values for the relative attenuation of the radiation emitted by this radionuclide that results from interposition of various thicknesses of Pb is shown in Table 2. For example, the use of 0.834 cm of Pb will decrease the external radiation exposure by a factor of about 1000.

These estimates of attenuation do not take into consideration the presence of longer-lived contaminants with higher energy photons, namely Indium In 114m.

To correct for physical decay of Indium In 111, the fractions that remain at selected intervals before and after calibration time are shown in Table 3.