Carbon-11 radioactively decays by positron emission with a half-life of 20.4 minutes. If a dosage of carbon-11 is administered to a patient for a PET scan, what percentage of carbon-11 will remain in the patient's system after 61.2 min?

Question

Quizplus · Accepted Answer

After 61.2 minutes, which is three half-lives of carbon-11 (20.4 minutes x 3 = 61.2 minutes), the amount of carbon-11 remaining would be (1/2)^3 = 1/8, or 12.5%.

Carbon-11 Radioactively Decays by Positron Emission with a Half-Life of 20.4