Ultrasound and Radiation

 Ultrasound, X-rays and Gamma Rays, Treatment

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  • Created by: tom
  • Created on: 14-04-11 12:00

Ultrasound

  • Ultrasound is a longitudinal wave
  • For a longitudinal wave, the particles vibrate in the same direction as the wave
  • For transverse waves, the particles vibrate at right angles to the direction of the wave
  • Longitudinal waves cannot travel through a vacuum
  • Ultrasound creates regions of high pressure called compressions and regions of low pressure called rarefactions
  • The amplitude of a wave is the maximum distance of a particle from its normal (or equilibrium) position
  • The wavelength of a wave is the distance occupied by one complete wave
  • The frequency of a wave is the number of complete waves in one second
  • Frequency is measured in hertz (Hz)
  • Ultrasound is used for ‘seeing’ inside our bodies without surgery
  • Ultrasound scans are used to check the condition of the foetus, breaking down kidney and other stones and measuring the speed of blood flow in the body
  • Ultrasound is reflected by different layers of tissue
  • Ultrasound is inaudible to the human ear
  • Unlike x-rays, ultrasound scans can be used to produce images of soft tissues and they do not damage living cells
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X-Rays and Gamma Rays

 

  • X-rays and gamma rays have the shortest wavelengths and carry the most energy. They are also penetrative of the electromagnetic waves, a property which is useful in medical imaging. When an X-ray photograph is taken:
  • X-rays are passed through the body and detected by a photographic plate
  • The X-rays pass through the flesh and are absorbed by the bone
  • A bone fracture is seem as a dark line on the white bone in an X-ray photograph
  •  A similar technique is used to examine the turbine blades of jet engines, to check for cracks
  • Gamma rays are useful for checking individual organs when used as a tracer. A radioactive isotope that emits gamma rays is injected into the body and when it has circulated it can be detected by a camera to give either a still or moving picture. The radioactive isotopes can be made so that they concentrate in particular areas of the body
  • Although they are only weakly absorbed by body tissue, X-rays and gamma rays are both ionising radiations. They can destroy cells and cause mutation in the DNA. Because of this:
  • Both are used in the treatment of cancer to destroy abnormal cells
  • Gamma rays are used to kill bacteria in food and to sterilise medical instruments
  • People who come into contact with X-rays and gamma rays need to be protected from damaging over-exposure
  • X-rays and gamma rays are produced in different ways. X-rays come from X-ray tubes and gamma rays are emitted by unstable nuclei. There is no difference in the waves
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Treatment

 

  • Some radioactive nuclei of atoms emit nuclear radiation
  • Alpha particles, beta particles and gamma rays
  • Gamma rays and X-rays are both used in medicine for treatment (therapy) and for finding out what is wrong (diagnosis)
  • In radiotherapy, several gamma ray sources producing wide beams are directed towards cancerous tissues to destroy the cancer cells
  • A radioactive tracer is a radioactive substance that is drunk or injected into the body
  • Only beta particles and gamma rays can pass through the skin. Hence a tracer is either a beta or gamma emitter
  • The function of some vital organs can be diagnosed using a radioactive tracer
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Comments

Ele.

This is good but please edit the cards so that all the text can be seen, if this means putting the info on two cards instead of one please do it.

Thanks,

Ele - Moderator

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