Using radiation

• Uses of radioactivity

  • Household fire alarms (smoke)
  • Irradiating food
  • Sterilisation of equipment
  • Tracing and gauging thicknesses of materials
  • Diagnosis and treatment of cancer
• How smoke alarms work

  1. Radioactive substance emits alpha radiation

  2. Emitted alpha particle ionises the air in the detector and causes a current to flow between the plates

  3. Smoke interferes with the radiation, the air is no longer ionised and so no current can flow

  4. Reduction in current flow triggers the alarm
• Uses of nuclear radiation in medicine

  • Examining of internal organs
  • Radiotherapy in the treatment of cancer
• Role of beta radiation in tracers

  • The tracer is inserted in your body, and targets a specific part of the body
  • The radioactive substance in the tracer releases beta radiation which can be detected by external machines
• How beta radiation is used to determine thickness

  1. A beta source is placed above the material and a detector is placed below it

  2. If there is an increase in radiation detected by the detector, too much radiation is passing through the material, and so it is too thin

  3. If there is a decrease in radiation is detected, then the material blocks too much radiation, and so it is too thick
• Why ionising radiation is dangerous

  • It can damage tissue and kill cells
  • It can cause cell mutations
• Precautions when using ionising radiation


  • Avoid handling the source directly (use tongs)
  • Wear radiation protective clothing
  • Keep the radiation in lead containers to reduce the amount of radiation that can escape
  • Keep exposure time to a minimum
• Long half life


  Makes a source more dangerous
• Precautions for doctors and patients using ionising radiation


  • Only a small dose is given to the patient so they are not exposed to too much
  • The radiation used has a short half life so it won't remain highly radioactive for long
  • Doctors and patients (when applicable) wear protective clothing
• Radioactive contamination

  The presence of unwanted radioactive nuclei on other materials
• Irradiation


  • The process of exposing a material to nuclear radiation
  • The material does not become radioactive
• How a radioactive tracer is used in medicine

  1. The tracer is placed inside the body

  2. The tracer releases gamma radiation which is detected by a detector which moves around the body

  3. This can then be used to produce a picture of the patient's body
• How a PET scanner works

  1. PET (positron emission tomography) uses a tracer, which is injected into the patient's body

  2. The scanner detects the gamma rays which are released by the trace

  3. Multiple images are taken and this is used to form a 3D image of the patient's body
• Isotopes used in PET scanners must be produced near the hospital because the isotopes used have a short half life so must be used soon after production