Medical Imaging


Mind map on the various non-invasive medical imaging methods. Used to revise for subjects like physics and applied science.
Bryony Hammatt
Mind Map by Bryony Hammatt, updated more than 1 year ago
Bryony Hammatt
Created by Bryony Hammatt about 9 years ago

Resource summary

Medical Imaging
  1. Radiography (xray imaging)
    1. Best for broken bones, dentistry & some soft tissues.
      1. Photographic film and xray Generator. Rays expose film and turn it black.
        1. No rays reached paper = white (bones and metal show up as white)
          1. Xrays are ionising and exposure has to be kept to a minimum.
            1. Xrays have contrasting agents that can boost attenuation coefficient of soft tissues - better distinguishing of soft tissues - in the form of an artifical contrast medium
              1. In the digestive system, barium is given containing barium sulfate to identify stomach/intestinal blockages.
              2. relatively Cheap
              3. CAT Scanning - computer tomography
                1. Produces more detailed picture than xray by putting the image together using a computer.
                  1. Consists of a rotating x-ray source and a ring of detectors surrounding the patient. Data produced builds up a detailed cross sectional image
                    1. CAT scan has 100X more ionising radiation than xray to be built up into a 3D image
                      1. This means that the patient is limited to the amount of CAT scans they can have, and it also puts the radiographer at risk.
                    2. MRI scanning - magnetic resonance imaging
                      1. Carries no known risks
                        1. Loud
                          1. Not good for young children/claustrophobes
                            1. Some patients may need sedation or restraint
                          2. Ring-shaped electromagnets that line the MRI unit
                            1. When switched on protons in the body (from hydrogen atoms) line up in the electromagnetic field
                              1. once lined up a radio frequency is emitted which disturbs proton alignment and causes them to rotate, emitting tiny radio frequency signals.
                            2. Expensive - maintenance of machine and supply of helium to be made into liquid helium to keep the electromagnetic coil cold is very costly.
                              1. Small radio frequency coil is used to cover relevant parts of the body to pick up signals from resonating protons, which allows them to then be converted into an image
                                1. Not appropriate for patients with metal implants
                                2. Term used to describe any method used to view the inside of the body without invasive surgery
                                  1. Ultra sound scanning
                                    1. Uses high frequency sound emitted from a transceiver unit, which rebounds off of tissue
                                      1. Gel has to be used so that air gaps do not disrupt the signal
                                      2. Cheap - only needs one unit
                                        1. Means it is accessible to LEDCs.
                                        2. Real-time imaging
                                          1. Useful in prenatal scans as is can detect deformities without invasive testing which could be harmful to the baby
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