Ultrasound

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  • Ultrasound
    • Properties of Ultrasound Waves
      • Ultrasound waves can't travel through vacumes because there are no particles for vibrations to bounce off of.
      • Ultrasound waves are longitudinal waves consisting of compressions and rarefactions.
        • Rarefactions are regions of lower pressure where particles are spread out.
        • Compressions are regions of higher pressure where particles a close together.
      • Ultrasound waves have a frequency higher than 20,000 Hz
        • Ultrasound waves can't be detected by the human ear. This is because our ears can only comprehend frequencies between 20Hz and 20,000Hz
    • Uses of Ultrasound
      • Breaking down stones e.g. Kidney stones
        • A high energy ultrasound wave is focused on the stone. The wave causes the stones to vibrate and break apart so that they can be excreted via the uretha.
          • Kidney stones are solid crystals created by subtances in urine. When these stones build up they can cause a blockage in the ureter causing pain.
      • Measuring blood flow.
        • When an ultrasound wave is reflected off a moving object the frequency of the echo changes. This is used in Doppler ultrasound scanners which can be used to check the speed of blood flow to the brain.
      • Pre-natal scanning to check that the foetus is developing properly .
      • Scanning soft tissue
        • 4. These readings are usually sent to a computer where they are combined to produce a detailed image of the area being scanned.
          • 2.When the wave meets a boundary between different materials (tissues, organs) some of the wave is reflected back through the material to a detector as an echo.
            • 1.Ultrasound waves are sent into the area of the patients body that is being checked.
          • 3.The detector calculates the depth of each boundary using the time taken for each wave to reflect and return.
            • The distance travelled by an ultrasound wave pulse can be calculated using the equation: distance travelled(m)= speed of the ultrasound wave(m/s)* time(s)
              • For example if ultrasound waves travel through water at 1400m/s and the time taken for the wave to reach the boundary and reflect back to the detector is 0.5s we the distance travelled by the wave is: (1,400*0.5) / 2= 350m
            • 2.When the wave meets a boundary between different materials (tissues, organs) some of the wave is reflected back through the material to a detector as an echo.
              • 1.Ultrasound waves are sent into the area of the patients body that is being checked.
      • Used in industry in quality control to check manufactured objects e.g. railway tracks don't have any damage.
        • The distance travelled by an ultrasound wave pulse can be calculated using the equation: distance travelled(m)= speed of the ultrasound wave(m/s)* time(s)
          • For example if ultrasound waves travel through water at 1400m/s and the time taken for the wave to reach the boundary and reflect back to the detector is 0.5s we the distance travelled by the wave is: (1,400*0.5) / 2= 350m
    • Advantages of Ultrasound
      • Ultrasound waves are not ironizing and are therefore safer to use than x-rays
        • As a result ultrasounds can be used to perform pre-natal scanning.
      • Ultrasound can produce images of soft tissue.
        • As a result ultrasounds can be used to perform pre-natal scanning.
    • Disadvantages of Ultrasound
      • Ultrasound produces less detailed images than x-rays. This extra clarity is essential when detecting small abnormalities.

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