Imaging

X-rays, MRI, CT/ CAT Scans, Ultrasound


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  • Created by: Jemma
  • Created on: 06-05-11 09:43

Imaging

X - Rays

Advantages

  • Cheap and easy
  • Can often be interpreted by any one (non - radiologist)
  • Quick and readily available
  • Good bone resolution
  • Mobile lung and breast screening units are possible

Disadvantages

  • Ionising radiation is harmful
  • High - voltage supplies are a hazard
  • Poor soft tissue resolution
  • 2D images
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Imaging

MRI

Advantages

  • Does not involve ionizing radiation
  • Strong magnetic fields and radio waves not thought to be harmful
  • Excellent soft tissue contrast
  • 3D images

Disadvantages

  • High cost
  • Needs special facilities to have the equipment
  • Need to take care that metal objects are not sucked in
  • Patients with pacemakers cannot be scanned
  • Some people feel claustrophobic
  • Extremely noisy
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Imaging

CT or CAT Scanners

Advantages

  • Provide more detail than conventional x - rays particularly for soft tissue
  • Often more readily available than MRI in the UK
  • 3D images

Disadvantages

  • Very high radiation doses
  • Much more expensive
  • Patient has to be very still so image is focused
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Imaging

Ultrasounds

Advantages

  • Safe
  • Relatively cheap equipment
  • More effective trhan X - Rays in producing images of sort tissue and some cancers
  • Can be used in keyhole surgery
  • Can measure blood flow and diagnosis of deep vein thrombosis (DVT)

Disadvantages

  • Cannot see through bone
  • Cannot visualise air filled spaces such as lungs as the sound waves are reflected at the tissue surface
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Imaging

X - Ray Facts

  • Produced when electrons hit a metal, which in hospital x - ray tubes, is usually tungsten. The x - rays then pass through the body and onto either a film cassette or digital detector
  • They use ionising radiation to produce a 2D image
  • X - Rays are a type of electromagnetic radiation towards the high frequency end of the spectrum, which are absorbed by high atomic density materials
  • Air in the bowels or lungs produce a dark/ black image + fat appears grey
  • Used to look for suspected bone injury and can be used for diagnoses of pneumonia or some lung diseases including lung cancer 

       (http://www.medimagesys.com/images/hospital_xray_machine.jpg)   X - Ray machine    (http://scienceblogs.com/gregladen/images/touch_x-ray.jpg)   An X - Ray

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Imaging

MRI Facts

  • MRI - Magnetic Resonance Imaging
  • Allows imaging of the interior body without x - rays or types of ionizing radiation
  • Capable of showing fine detail of different tissues and can be used to diagnose conditions that can affect the brain and nervous system
  • It can do this by producing a map which depends on the density of hydrogen in the body
  • They produce images which are 2D slices through the body
  • They allow you to see very small details which makes it an important tool for doctors

      (http://wurzelmeone.files.wordpress.com/2010/08/mri_scanner_470x3521249527062.jpg)  MRI scanner    (http://www.fmrib.ox.ac.uk/education/fmri/images/sagittal_scan.jpg/image_preview)  Example of a scan

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Imaging

CT and CAT Scans

  • They use x - rays to produce images of one slice of the body at one time
  • The patient lyes of the table and is moved through a doughnut shaped machine, this creates images that are slices through the patient
  • It moves the x - ray tube and detector in a circle taking sliced x - ray images fromn all angles of the body
  • The images are then processed by a computer which produce a cross sectional image
  • CT/ CAT scans are ideal for examining sort tissue e.g. lungs, liver, kidneys, bladder and brain

       (http://bluefingers.files.wordpress.com/2008/03/ct-scan.jpg)  CT scanner         (http://upload.wikimedia.org/wikipedia/en/0/04/Brain_CT_scan.jpg) Example of a scan  

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Imaging

Ultrasound

  • Uses sound waves with frequencies between 1 and 10MHz to look inside of the body
  • The frequencies above are too high to be heard by humans
  • A gel is used so the probe makes good contact with the skin. The time taken indicates how deep in the tissue the ultrasound wave is being reflected
  • Thought to be safe as does not use ionising radiation
  • Computers can now generate 3D images and 4D videos can be made

         Ultrasound       (http://bdfbuzz.files.wordpress.com/2010/04/2d_ultrasound3.jpg)   Image

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Comments

SummerAllen

This is brilliant!! Well done JEMMA!! :) xxxx

liv

wow this is so helpful! 5 stars!

za

This is GREAT! Thanks

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