Question

BIOPHYSICS

Cobalt-60 (60Co), is a synthetic radioactive isotope of cobalt with a half-life of 5.2713 years. It is an isotope that emits gamma rays essential to the medical community for cancer treatments, as well as sterilization of medical devices. Cobalt-60 is used as a radiation source for medical radiotherapy where it is used in cancer treatment to control or kill malignant cells. Cobalt-60 is used as the radiation source in Gamma Knife equipment that enables non-surgical treatment of brain tumors.

Suppose you purchased a high activity cobalt source with 106 Curie.

After how many years will the activity of this source be reduced to 10% of its initial value? (include calculations in your answer)

Hints: Remember unit conversions (years to second, Ci to Bq). First find number of nuclides that creates this much activity. Use Avogadro’s number to find kg.

Answer 1