X-rays in Medicine

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  • Created by: Jo Wells
  • Created on: 19-04-13 23:11
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  • X-rays in Medicine
    • x-ray images are used in hospitals for medical diagnosis
      • x-rays are high frequency, short wavelength electromagnetic waves
        • wavelength roughly same size as the diameter of an atom
      • are transmitted by (pass through) healthy tissue, but are absorbed by denser material - e.g. bone & tissue
      • they affect photographic film in same way as light - can be used to take photographs
      • x-ray photographs can be used to diagnose many medical conditions - e.g. bone fractures/dental problems
      • x-ray images can be formed electronically using charge-coupled devices (CCDs)
        • silicon chips divided up into millions of pixels
          • detect x-rays and produce electronic signals - used to form high resolution images
    • CT scans use x-rays
      • Computerised Axial Tomography (CT or CAT) scans - use x-rays to produce high resolution images of soft & hard tissue
        • patient is put inside cylindrical scanner & an x-ray beam is fired through body from an x-ray tube & picked up by detectors on opposite side
          • x-ray tube & detectors are rotated during scan
            • computer interprets signals to form an image of a 2D slice through the body
              • multiple 2D images can be put together to form a 3D image
    • x-rays can be used to treat cancer
      • x-rays can cause ionisation - high doses will kill living cells
      • can therefore be used to treat cancers
        • x-rays can cause ionisation - high doses will kill living cells
        • have to be carefully focused & at right dosage to kill the cancer cells withougt damaging too many other cells
      • to treat cancer
        • x-rays are focused on tumour using a wia wide beam
          • beam is rotated round the patient with tumour at the centre
            • this minimises chances of other cells being exposed to radiation - reduces chances of damaging rest of the body
    • radiographers take precautions to minimise radiation dose
      • prolonged exposure to radiation can be damaging to the body
      • radiographers wear lead aprons, stand behind a lead screen or leave the room whilst the scan is taking place
      • lead is used to shield areas of the patients body that aren't being scanned & exposure times to x-rays are always kept to an absolute minimum


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