A doctor uses radioactive iodine-123 to obtain an image of a patient's thyroid gland.
Beta-minus (β−\beta^-β−) radiation consists of:
A. electromagnetic waves B. helium nuclei C. high-speed electrons D. protons
State what is meant by the term half-life of a radioactive isotope.
The doctor injects a solution containing iodine-123 into the patient. A detector positioned outside the patient detects the emitted gamma rays to reconstruct the image. Suggest why isotopes that emit only alpha radiation are unsuitable for this medical imaging technique.
Iodine-123 has a half-life of 13 hours13\text{ hours}13 hours.
A sample of iodine-123 has an initial activity of 320 MBq320\text{ MBq}320 MBq.
Explain why the activity of any radioactive sample reduces over time.
Calculate the activity of the iodine-123 sample after 39 hours39\text{ hours}39 hours.
