Technetium-99m is a radioactive isotope commonly used in medicine as a radioactive tracer. A radioactive tracer is an isotope injected into the body to help create images for diagnosis of health problems. Technetium-99m has a half-life of 6 hours. If a patient receives a dose of technetium-99m one morning, about what percentage of the technetium-99m will be left in the patient's body 12 hours later?

Question

a
25.0%
b
12.5%
c
93.8%
d
6.25%

Answer 1

To find the percentage of technetium-99m left in the patient's body 12 hours later, we need to determine how many half-lives have passed.

Since technetium-99m has a half-life of 6 hours, after 6 hours, half of the initial amount will remain. This means that after 12 hours (2 half-lives), 25% (50% x 50%) of the initial amount will remain.

Therefore, the correct answer is a) 25.0%.