Physics Radiation in Medicine-P3.1

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  • Created by: amy
  • Created on: 03-04-13 18:31

P3.1-How is radiation used in medicine?

Visible light is an example of radiation (energy carried by waves or particles from a source). Light and other types of radiation are used to identify and treat medical problems.

Topic 3.1

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Radiation for diagnosis

  • Doctors use radiation to show images of the inside of the body

Visible light reflects off features to form an image, this is used in an endoscope

X-rays are absorbed by some materials inside the body but not others so a negative image is produced, this is used in X-ray photography and CAT scanners

The movement of substances emitting gamma radiation is detected and their positions are shown on a screen, used in PET scanners

High frequency sound waves can reflect off features inside the body to form an image, this is used in an Ultrasound, in an ultrasound scanner.

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Radiation for medical treatments

Ionising radiation can kill harmfull cells!

  • Ionising radiation can create reactive ions in the body, which can cause damage.
  • Gamma rays and X-rays are ionising and can be used to damage/destroy cancer cells

Various types of non-ionising radiation can also be used in medical treatments

  • Light radiation isn't ionising however it is use in laser eye treatment
  • Ultrasound radiation isn't ionising however it is used to treat swollen tissues
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Radiation for medical treatments 2


The further away you get from the source, the amount of radiation you get lessens

Depending on the type of cancer cell you have, the doctor will place the source at different distances from the tumour.

The intensity of radiation is also decreased if the medium it is travelling through is denser. 


Intensity=power of incident radiation (incoming beam of radiation)/area which it is spread

Power is measured it Watts and area is measured in metres squared so the unit will be W/m2

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