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Science

Radioactive substances

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Using radiation

Here are some examples of how radiation is used:

  • in smoke detectors
  • for sterilising medical instruments
  • for killing cancer cells
  • for dating rocks and materials such as archaeological finds
  • in chemical tracers to help with medical diagnosis
  • for measuring the thickness of materials in, for example, a paper factory

Tracers

Doctors may use radioactive chemicals called tracers for medical imaging. Certain chemicals concentrate in different damaged or diseased parts of the body, and the radiation concentrates with it. Radiation detectors placed outside the body detect the radiation emitted and, with the aid of computers, build up an image of the inside of the body.

When a radioactive chemical is used in this way it is not normally harmful, because:

  • it has a short half-life and so decays before it can do much damage
  • it is not poisonous

Emitters of beta radiation or gamma radiation are used because these types of radiation readily pass out of the body, and they are less likely to be absorbed by cells than alpha radiation.

Monitoring the thickness of materials

Radiation is used in industry in detectors that monitor and control the thickness of materials such as paper, plastic and aluminium. The thicker the material, the more radiation is absorbed and the less radiation reaches the detector. It then sends signals to the equipment that adjusts the thickness of the material.

Check your understanding of this by watching the simulation.

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