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Ca-45 Standard Operating Procedures


Calcium-45 is a commonly used radionuclide with a half-life of 165 days, emitting only beta particles with a maximum energy of 0.252 MeV (Million Electron Volts) and an average energy of 0.075 MeV. The beta particles from Ca-45 travel a maximum of 61 cm in air. See chart below for the decay rate information for Ca-45.


The major concern with using Ca-45 is that it cannot be easily monitored during it's use, therefore, special precautions are needed to keep the work environment clean. The regular use of wipe testing is the only way to insure that your work space is not contaminated. Contamination on the skin will not likely cause a significant dose to the skin, however, it could lead to the internal absorption of Ca-45. The ingestion ALI is 2 millicurie.


Glass and plastic are the best shields for beta particles from Ca-45.


A tiny drop of contamination from Ca-45 can be easily detected with a wipe test from a Liquid Scintillation Counter. Most Geiger Counters will not efficiently detect the presence of Ca-45.

Equipment / Supplies

The following equipment and supplies must be available:

  • disposable latex or plastic gloves.
  • a full-length lab coat.
  • radioactive waste receptacle
  • pipettes dedicated to the use of Ca-45.
  • commercial decontaminate, i.e. DuPont's "Count Off".
  • absorbent bench covering or tray.

Safety Rules

If the following safety precautions are used, personnel radiation exposure will be as low as reasonably achievable.

  1. Designate a specific area of the lab for Ca-45 handling.
  2. Full-length lab coats must be worn by all persons who handle Ca-45.
  3. Protect your hands from becoming contaminated from spills by wearing two pairs of disposable gloves.
  4. Never pipette Ca-45 or any radionuclide by mouth.
  5. Only use pipettes which have been dedicated to your specific use of Ca-45.
  6. Pipettes will easily become contaminated and therefore, should not be shared with others.
  7. If you have reason to believe that your gloves are contaminated, immediately dispose of them in the radioactive waste container.

Post-Use Procedures

After handling Ca-45:

  • Conduct a monthly (weekly) wipe test.
  • Count weekly wipes in a Liquid Scintillation counter.
  • Check all equipment, centrifuges, water baths for contamination.
    • If any contamination is found, use a commercial radiation contamination remover (i.e. Count Off) with paper towels to clean up the equipment.
    • Place the towels in the radioactive waste receptacle.
  • If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is Ca-45, maximum cpm found, and the date you measured the level.
  • Check the work bench and floor.
    • If contamination is found, it can usually be removed easily with "Count Off". If it cannot be removed, contact the RSO to obtain shielding materials.
    • Inform your fellow lab workers if any unremovable contamination is found.
  • Check the normal trash container to make sure no radioactive waste has been accidentally placed there.
  • Store the waste temporarily in containers marked with labels "Radioactive Waste-Do Not Empty". These containers are available in the RSO.
  • Call the RSO if you have any questions about where to survey.
  • Wash your hands thoroughly.
  • Bring the waste frequently to the Radwaste Room. We accept waste by appointment only.

Any questions about these procedures?

Call the Radiation Safety Office: 464-6510

Days Elapsed % of Activity Remaining Decay Factor
0 100.0 1.00
10 95.9 0.959
20 91.9 0.919 
30 88.2 0.882
40 84.5 0.845
50 81.1 0.811
60 77.7 0.777
70 74.5 0.745
80 71.5 0.715
90 68.5 0.685
100 65.7 0.657
110 63.0 0.630
120 60.4 0.604
... ... ...
1650 (10 half-lives) 0.1 0.000

For example, if your vial contained 500 microcuries of Ca-45 on 7/1/90, the amount of activity remaining on 7/11/90 (10 elapsed days) would be:

Activity x Decay Factor = 500 microcuries x 0.959 = 479.5 microcuries