GCSE Physics (AQA)

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Choosing Radioactive Tracers

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Atomic structure Hazards and uses of radioactive emissions and of background radiation

Choosing Radioactive Tracers

3:13 Radiation in Medicine
Spec 4.4.3.3
Previous Radioactive Tracers Next Radiation in Cancer Treatment
  • Isotopes for radioactive tracers must be chosen carefully to avoid harming patients.
  • Radioactive tracers are used to investigate organs internally, with careful consideration of dosage to minimize cancer risk.
  • Radiation must be strong enough to detect for organ mapping, but not too weak to be ineffective.
  • The half-life of a tracer must be long enough for diagnosis but not too long to avoid prolonged contamination.
  • Bismuth 83 has a short half-life (45 minutes) and is unsuitable as it decays before reaching the organ.
  • Strontium 90 has a long half-life (28 years) and is unsuitable due to long-term decay inside the body.
  • Beta or gamma emitters are preferred as they can escape the body, unlike alpha radiation which is stopped by tissue and skin.
  • Alpha radiation is highly ionizing and dangerous inside the body, while beta and gamma are less ionizing and spread out.
  • Technetium 99 is a commonly used tracer with a half-life of six hours, ideal for reaching organs without long-term contamination.
  • Technetium 99 emits gamma radiation, which can easily leave the body and cause minimal damage.
  • Understanding the properties of isotopes is important for determining their suitability as tracers in exams.

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