The radiopharmacy receives an order for a 4 mci 99mtc-mdp (bone scan dose) to be injected at 12: 00 pm. the pharmacist has prepared 99mtc-mdp with the concentration of 10 mci/ml at 6: 00 am. what volume of the dose should be dispensed to provide the dose as ordered? the half-life of 99mtc is 6 hours

0.4 ml

Explanation:

The mother solution contains 10 mCi, but the patient just need 4 mCi.

So using a rule of three, it would be:

10 mCi - 1 ml

4 mCi - X       X  = (4x1) /10 = 0.4 ml

And considering the half life of 6 hours, need to pass 18 h to have a dose in the body that is insignificant. (at the first 6 h it will have 2 mCi, at the next 6 hours 1mCi, at the next 6 hours 0.5 mCi)

So it would be 0.4 ml of the mother solution every 18 h.