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  • Created by: Dan Riley
  • Created on: 08-05-14 09:07
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    • X-RAY
      • The part of your body being pictured is positioned between the X-ray machine and photographic film.
      • You have to hold still while the machine briefly sends electromagnetic waves (radiation) through your body exposing the film to reflect your internal structure.
      • Advantages
        • Cheap
        • Quick to do
        • Can be interpreted by a non-radiologist
        • Readily available
        • Good bone resolution
      • Disadvantages
        • Ionizing radiation is harmful
        • Poor soft tissue resolution
        • 2-D images
      • Bones, tumors and other dense matter appear white or light because they absorb the radiation.
        • Less dense soft tissues and breaks in the bones let radiation pass through, making these parts look darker on the X-ray film.
    • CT OR CAT scans
      • The CT scanner uses a rotating X-ray tube.
      • The patient is moved through this moving beam which collects a series of images called tomograms.
      • The computerised images are more detailed than normal X-rays and help show clear pictures of organs inside the body, blood  vessels, bones and tumours.
      • Advantages
        • More readily available than MRI
        • Provides more detailed images, specifically soft tissue
        • 3-D images
      • Disadvantages
        • Very high radiation doses
        • Very high cost
        • Patient has to be very still so image is focused
          • If patient is claustrophobic then they may need to be sedated
    • MRI scans
      • A strong magnetic field is created by passing electrical currents through the wire loops
      • While this is happening, other coils in the magnet send and receive radio waves. This triggers protons in the body to align themselves.
      • Once aligned, radio waves are absorbed by the protons, which stimulate spinning.
      • Energy is released after "exciting" the molecules, which in turn emits energy signals that are picked up by the coil.
      • This information is sent to a computer which processes all the signals and generates it into an image.
      • This creates a 3-D image of the area being examined.
      • Advantages
        • Does not involve ionising radiation
        • Strong magnetic fields and radio waves not thought to be harmful
        • Excellent soft tissue resolution
        • 3-D images
      • Disadvantages
        • High Cost
        • Cannot scan patients with metal implants
        • Unsuitable for claustrophobic or obese patients
    • Ultrasound
      • Ultrasound is transmitted and received using a probe.
      • A gel is used to fill the gap between the probe and the skin.
        • This is to prevent reflection at this surface.
      • The waves that do penetrate are reflected off internal organs, barriers, layers of tissue and interfaces.
      • The echo patter of the returning waves is picked up by the probe.
      • The ultrasound is viewed as a real-time picture on a monitor.
      • Advantages
        • Safe- does not involve ionising radiation
        • No known harmful side effects
        • Good soft tissue resolution
        • No-invasive
        • Relatively cheap
      • Disadvantages
        • Cannot see though bone
        • Cannot visualise air filled spaces, such as lungs, as the sound waves are reflected at the tissue surface


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