51Cr

(Chromium-51)

Chromium-51 is used at WSU mainly in cell labeling. Its short half-life and moderate gamma energy give it certain advantages for such work.

Physical Data (ICRP 38 and RHH)

Decay mode electron capture to stable 51V

Half-life 27.7 days

Major emissions 320 keV gamma (about 9%)

about 5 keV x-rays (about 45% total)

about 5 keV auger electrons (about 68% total)

Half-value thickness about 2 mm Pb

about 9 mm Fe, about 27 mm Al

Dose rate constant about 160 mrem/hr at 1 cm per mCi

Biological Data (ICRP 30)

About 0.1 of intake becomes uptake. Form is or usually becomes Cr+++. Of uptake, about 0.3 is excreted within 1 day, 0.4 becomes distributed uniformly within the body with about 6 day half-life, 0.25 become uniformly distributed with about 80 day half-life, and about 0.05 goes to bone with about 1,000 day half-life (approximately infinity compared to the 28-day physical half-life).

Committed dose equivalents per µCi of intake include about 0.9 mrem to LLI (from ingestion), 2 mrem to lung (from inhalation) and lower doses to other organs.

Comments - Precautions

The 320 keV photons from 51Cr are more penetrating than emissions from iodines, phosphorus, etc., used at WSU. However, the low intensity results in modest dose rates from typical quantities in use; hence handling problems are not severe.

Normal precautions for working with 51Cr include the usual wearing of lab coat and gloves, wearing personnel badge, wearing TLD finger dosimeter when handling concentrated material.