Ultrasound

Ultrasound

1. Human ear

   • Detects sound waves with frequencies between 2Hz and 20,000Hz
     • Higher frequencies than this are called ultrasound waves

2. Electronic systems

   • Can produce ultrasound waves
   • When a wave meets a boundary between two different materials, part of the wave is reflected
     • The wave travels back through the material to a detector
       • The time it takes to reach the detector can be used to calculate how far away the boundary is
         • The results may be processed by a computer to give an image
     • In the time between a transmitter to a boundary and back
       • Twice the distance to the boundary

3. Formula

   • s = v * t
     • 's' is the distance travelled in metres, 'm'
     • 'v' is the speed of the ultrasound wave in metres per second, 'm/s'
     • 't' is the time taken in seconds, 's'

4. Uses

   • To scan unborn babies
   • Scan soft tissue
     • Eye
   • Theropy
     • Shatter kidney stones into smaller pieces

5. Risks

   • Non-ionising
   • Safer than X-rays