Radioactivity (6.28-6.35)

Uses and dangers of radioactivity

follows specification points


Uses - household smoke alarms (6.28)

Household smoke alarms

  • These contain a source of alpha particles
  • Detector measures alpha particle movement across small gap
  • When smoke enters the detector, it absorbs alpha particles and number crossing gap will drop
  • This is registered and triggers alarm
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Uses - irridiating food (6.28)

Irridiating food

  • This is used to preserve food
  • Gamma rays destroy bacteria on fruit but does not change the fruit
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Uses- Sterilisation of equipment (6.28)

  • gamma rays are used to sterilise surgical equipment
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Uses - tracing (6.28)

Industrial tracing

  • A gamma source is put into contents of pipes to detect leaks
  • When there is a leak, liquid seeps into ground→building up gamma emissions→ these can be detected by GM-tube
  • The ground can be dug up to repair leak
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Uses - gauging thickness (6.28)

Gauging thickness

  • used with beta emitters for making paper and aluminium foil
  • if the paper or foil is too thick it will absorb more beta particles→detector receiving fewer particles sends signals to increase rollers force
  • and vice versa is it is too thin
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Uses - Cancer diagnosis and treatment (6.28)

Medical tracing and diagnosis of cancer

  • Gamma souce passing through body can be followed as it flows through the body
  • Changes in the amaount of gamma rays emitted could indicate a blockage, highlighting a problem

Treatment of cancer

  • Gamma ray beams can be used to kill cancerous tumors
  • The beams are aimed at the tumor from different dirrections to maximise dosage to tumor and minimise dosage to surronding tissue.
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Dangers of ionising radiation (6.29)

  • radioactive radiation is ionising → ionises atoms as an effect of knocking electrons out of body
  • radioactive radiation can also deposot large amounts of energy into the body
  • these processes change the ways cells behave ie. mutating DNA and damage or destroy cells
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Uses and dangers of half-life (6.30)

  • half-life has to be long enough for radioactive isotope to produce useful measurements → for medical procedures for example
  • half-time has to be short enough for it to decayt o safe levels short after use
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Safety precautions (6.31)

  • limit exposure time 
  • keep radioactive sorces in lead lined box when not in use
  • wear protective clothing and face masks
  • handle radioactive materials with tongs
  • monitor exposire to radioactive material with detector badges
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Compare contamination and irradiation (6.32)

  • Contamination is when an object has a radioactive source on or in it and becomes radioactive for as long as this is the case
  • However irradiation is when an object is exposed to radioactivity outside the object and does not become radioactive itself
  • Contamination can be useful in medical and industrial tracers - but care must be taken that is doesnt go when unwanted
  • Contaminating with isotopes with a short half-life can limit exposure  - but it is difficult to ensure that small amounts aren't left over
  • Contamination can allow imaging processes to replace invasive surgeries - but could potentially damage healthy cells
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Compare treatment of tumors using radiation (6.33)

  • Gamma ray beams can be aimed at tumors from amany directs from outside the body 
  • tumors can be treated by injecting radioactive material in tumor
  • in both cases cancer cells absorb a high does of the energy
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PET scanners + producing isotope nearby (6.34 +6.3

  • uses radioactive isotopes as medical tracers inside the body and cause gamma rays to be produced which can be detected outside the body, highlighting any potential problem
  • they have short half-lives so they decay  to safe levels soon after use
  • therefore they must be produced nearby so they are still active and useful when they get ot the patient
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