1. 100 mCi of 198Au (which has a half life of 2.7 days) is given to a patient for cancer therapy. If none is eliminated biologically, how much is left in two weeks?
2. 1g of 131I is administered to a patient. If, after 24 days, there is 1/8 g left, what is its half life?
3. 3H (tritium) is one radioisotope used for whole body scans. Its physical half life is 12.3 years, and its biological half life is 19 days. What is its effective half life?
