Radioactive Tracers

• What is a radioactive tracer defined as?

  A radioactive substance absorbed by tissue
• Why are gamma emitters preferred as radioactive tracers?

  They don't ionise tissues as much
• What is a molecule labelled with a radioactive isotope called?

  A radiopharmaceutical product
• What must a good tracer molecule do in the body?

  Not affect regular body function
• Name one common radioactive tracer that emits gamma radiation.

  Technetium-99m
• What does the 'm' in Technetium-99m refer to?

  A metastable excited state of the nucleus
• What is the half-life of Technetium-99m?

  6.0 hours
• How does a radioactive tracer appear on a gamma camera?

  As a bright area on the screen
• What does tracer-labelled glucose highlight?

  Areas of higher respiration, like tumours
• What can labelling white blood cells show?

  The location of an infection in the body
• What does labelling red blood cells highlight?

  Areas with decreased blood supply
• What is the advantage of using a gamma-emitting tracer?

  It can be easily detected outside the body
• Why is gamma radiation preferred over beta radiation for tracers?

  Gamma radiation does little damage to cells
• What is the half-life of Iodine-131?

  8.0 days
• What type of particles does Iodine-131 emit?

  Beta-minus particles and gamma photons
• What is Iodine-131 commonly used for?

  To assess thyroid activity
• Why has Iodine-132 replaced Iodine-131?

  It doesn't emit beta and has a shorter half-life
• What is the half-life of Indium-111?

  68 hours
• What types of cells can Indium-111 label?

  Red blood cells and white blood cells
• What are the essential properties of a radioactive tracer?

  • Must be a gamma emitter
  • Low-energy gamma rays to reduce ionisation damage
  • Short half-life to minimize patient dose
• Why are the chemical properties of tracers important?

  They determine the tracer's affinity for organs
• What are the advantages of using gamma-emitting tracers over beta-emitting tracers?

  Gamma tracers are less ionising and detectable
• How do different molecules affect tracer accumulation?

  They can target specific organs or tissues
• What is the energy of gamma photons emitted by Indium-111?

  170 keV and 250 keV
• What is the role of a gamma camera in using radioactive tracers?

  To detect the radiation emitted by tracers
• How does the half-life of a tracer affect its use in medicine?

  A short half-life reduces patient exposure
• What is the significance of the energy of gamma radiation emitted?

  It affects the detection and safety of the tracer
• What is the primary use of Technetium-99m?

  Diagnosis in medical imaging
• How does labelling with radioactive isotopes help in medical diagnosis?

  It allows visualization of specific tissues
• What factors determine the choice of a radioactive tracer for a specific medical application?

  Radiation type, half-life, and affinity