Ultrasound

Ultrasound

sound with a higher frequency than what humans can hear (above 20,000 Hz)
1. Specific electrical systems can produce electrical oscillations of any frequency these can then be converted into mechanical vibrations to produce sound waves with a frequency above 20,000Hz, ultrasound
ultrasound waves get partially reflected and refracted at a boundary between media
1. when a wave passes into different media some of the wave is reflected off the two medias boundary and some is is sent through the media and refracted, so partial reflection
  1. this means a pulse of ultrasound can be pointed at an object and wherever there are boundaries between two medias some of the ultrasound gets reflected back
    1. time taken for the reflections to reach a detector measure how far away the boundary is
      1. this is how ultrasound imaging works
      2. finding distance between boundaries may be required so this is the formula: distance(m)=speed(m/s)*T(s)
USES
1. ultrasound can be widely used in medicine from investigating blood flow in organs to diagnosing heart problems
  1. ultrasound can be used to break down kidney stones, kidney stones are hard masses which can block the urinary tract an ultrasound beam concentrates high energy waves at the kidney stone turning it into sand like particles which exit the body through urine its good as no surgery is needed and relatively painless
  2. scanning of a foetus, ultrasound waves pass through the body however reflect and refact at boundaries (e.g boundary between fluid in womb and skin of fetus) some of the wave is reflected back and detected the timing and ditribution of these echoes are processed by a computer to produce an image of the fetus
  3. safety, issues and comprimises
    1. safety: ultrasound waves are non-ionising and safe compared to x-rays which are ionising and very dangerous to a developing fetus as they cause cancer in high doses. CT scans use allot more x-ray radiation than standard x-rays so patient is exposed to even more ionising radiation, generally CT scans arent used unless necessary due to the increased radiation dose
    2. image quality: ultrasound images are typically fuzzy so it's harder to diagnose some conditions, then x-rays produce good images of bone and metal but not much else however CT scans produce very detailed images making diagnoses easy as they produce high resoloution images, 3D images can be used to plan complicated surgery

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	Erstellt von Jack Willepotte vor fast 9 Jahre