Technetium-99m ( ) is a radioactive tracer that emits a gamma ray useful for medical…
CHEMISTRY · Multi-part · US High School · Chemistry · Atomic Structure & Nuclear · Atomic Structure & Nuclear
Problem
Technetium-99m (99mTc) is a radioactive tracer that emits a gamma ray useful for medical imaging. A patient receives an injection whose initial activity is 5.0 mCi (millicuries). The half-life of 99mTc is 110 min.
(a) Calculate the activity of the tracer 5.0 h after injection. Give your answer in mCi.
(b) Determine the time, measured from the moment of injection, at which the activity will first drop below 0.50 mCi.
(c) Explain why isotopes used for diagnostic imaging are chosen to have half-lives in the range of a few hours rather than several days. Your explanation should consider both patient safety and image quality.