Ultrasound Flashcards
What is the range of normal hearing?
20Hz up to 20000Hz
What is ultrasound?
Any sound with a frequency too high for humans to hear, any sound with a frequency above 20000Hz, can be produced electronically
What 3 things can ultrasound be used for?
Measuring distance, medical scanning, cleaning and smashing
How do you measure a distance using an ultrasound?
When ultrasound meets a boundary between two different materials, some will be reflected and some will be transmitted. A detector can pick up the pulse of reflected ultrasound and display it on an oscilloscope screen. The longer it takes the reflected pulse to reach the detector, the further the boundary is from the detector
How do you form an image using the ultrasound?
By moving the ultrasound transmitter across a surface which produces multiple reflections and the computer using the reflected pulses to create an image
What do each square on a oscilloscope represent?
A certain length of time. This is the time base setting
What equation is used to calculate distances from ultrasound?
Distance = speed x time
How is ultra sound used in medical scanning? (babies)
The ultrasound is partially reflected everytime it meets a boundary between different tissue types. A detector picks up the reflected pulses, which are processed by a computer to give an image of the fetus
What can ultrasound also be used for in medical scanning?
Look at damaged ligaments, the stomach, liver, heart and kidneys, tumours
What is ultrasound vibrations be used for in cleaning and smashing?
To remove tartar from teeth and to smash kidney stones without the need for an operation
Compare ultrasound and x-rays
Ultrasound is non-ionising and will not damage body cells. X-rays are ionising and can damage or kill healthy body cells
Ultrasound scans can be produced over a long period of time. X-rays are harmful in large doses, used for only short amounts of time. Ultrasound images are less detailed than x-rays. X-rays images more detailed.
