Hazards+ uses of radioactive emission + background radiation

• half life and radioactive materials in medicine

  • nuclei with short HL - high activity so are dangerous but not for long
  • nuclei with long HL - low activity so are less dangerous but last ages
  • bigger mass of radioactive material - give out higher levels of radiation
• Treatment for cancer- destroying internal tissue

  • small implant that has radioactive material is in body by the tumour
  • needs:
  • short/medium HL, enough time to kill tumour but not harm healthy cells
  • medium/high penetration so it passes into the tumour
  • low ionisation, minimise damage to body tissue
  • radiation type: beta or gamma
• Smoke Alarms

  • have a radioactive source that emits alpha particles into air gap in electric circuits
  • alpha particles ionise the gap - complete circuit - current flows
  • smoke gets into gap - absorb ions - current drop, ALARM SOUND
  • needs:
  • long HL, last longer
  • low penetration, radiation can't escape the case
  • high ionisation, ionise air gap
  • radiation type: ALPHA
• Automatic thickness monitoring

  • pair of rolls between foil - pass through and reduce thickness
  • radioactive source emits beta on one side of foil, geiger counter on other side detects it
  • low reading = too thick foil, rolls move closer
  • high reading = too thin foil, rolls move apart
  • needs:
  • long HL, usable for longer
  • medium penetration, varied amounts of radiation pass through different foil thickness
  • ionisation isn't important
  • radiation type: BETA
• Treatment for cancer - external tissue destroying

  • arrow beam of gamma radiation is produced by radioactive cobalt source, directed at tumour
  • needs:
  • long HL, source is usable for as long as possible
  • high penetration, radiation needs to pass into body
  • low ionisation, minimise damage to healthy body tissue
  • radiation type: beta or gamma
• Radioactive tracers for internal organs

  • no surgery, patient ingests small dose of radioactive substance, flow of this through body is followed + problems diagnosed
  • eg: radioactive iodine can find out if there's a blocked kidney. Place detectors outside body- high reading means iodine is trapped, blocked.
  • needs:
  • medium HL, time for tests but needs to decay soon
  • high penetration, so radiation passes out body to be detected
• Assess risks and benefits of medical procedures that use radiation (including occupation and location)

  • occupation:
  • a worker in a nuclear powerplant is likely to receive a higher radiation dose than a member of the public
  • location:
  • someone living in Cornwall where there is a high level of radioactive radon-222 gas (from decay of rocks containing uranium) is likely to receive a higher dose
• Gamma cameras to explore internal organs

  • patient injected with substance that emits gamma radiation
  • organ absorbs it, gamma camera is now near substance
  • substance emits gamma that enters via holes in camera's lead grid, passes on to detector
  • only gamma emitted by the nuclei directly below point of detection is picked up
  • computer builds image of where substance is in organ
• Gamma cameras to explore internal organs

  • needs:
  • medium HL, enough time to test but fast decay
  • high penetration, radiation pass out body to detect
  • low ionisation, minimise damage to body tissue
  • radiation type: gamma
  • any substance used needs to decay to stable, NON-TOXIC isotope
• • radiation dose is measures in sieverts (Sv)
  • 1000 millisieverts (mSv) = 1 sievert
  • average person is exposed to 2.7mSv per year