A radioactive tracer used for medical diagnosis should ideally have
Correct answer: B. a short half life and emit gamma rays that escape the body for detection
- A. a long half life and emit alpha particles
- B. a short half life and emit gamma rays that escape the body for detection
- C. a very long half life and emit beta particles
- D. no radiation at all
Explanation
Gamma radiation escapes the body so an external camera can detect it, and a short half life means the activity falls quickly once the scan is done, limiting the patient's dose. Technetium 99m, with a six hour half life, is the workhorse of nuclear medicine for exactly these reasons. Alpha emitters would deposit all their energy inside the tissue and be detected by nothing.
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About Biological and Medical Uses of Radiation
Radiation in medicine includes X-rays and gamma rays for imaging, radioactive tracers for diagnosis, and controlled radiation for destroying cancerous tissue. The topic also covers CT scans, PET imaging, radiotherapy, sterilisation, half-life and dosage, alongside biological damage, shielding and the need to balance diagnostic or therapeutic benefit against exposure.
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