Ultrasound is sound with a frequency too high for humans to hear (over 20,000 Hz).
1 of 10
What is an x-ray?
High frequency, short wavelength electromagnetic waves which are used in hospitals for medical diagnosis, e.g. bone fractures, dental problems.
2 of 10
What are CT scans?
X-ray images are taken from a number of angles, a computer processes the results to from a 3D image of that body part.
3 of 10
How do CT scans work?
The patient is put inside a cylindrical scanner, and an x-ray beam is fired through the body from an x-ray tube and picked up by detectors on the opposite side. The tube and detectors are rotated during the scan. A computer generates a 2D image.
4 of 10
What happens to ultrasound when it hits a media?
When an ultrasound waves passes through one medium to another some of the wave gets reflected off the boundary between the two media and some is transmitted (and refracted). This is partial refraction.
5 of 10
How does an ultrasound scan work?
1) Place a transmitter reciever on the body. 2) A pulse of ultrasound is sent passing through the body. 3) Parts of the waves are reflected back at boundaries. 4) The ultrasound detects the reflections. 5) Computer processes timings to make an image.
6 of 10
How do you find a boundary with ultrasound?
Oscilloscope tracers are used to find boundaries. Distance = speed times time divided by 2.
7 of 10
What are the harms to using x-rays?
X-rays are harmful as they have enough energy to remove electrons from atoms/molecules to form ions. This is called ionisation. This can kill cells or damage DNA leading to cancer.
8 of 10
What precautions do radiographers have to take?
They need to take many precautions to minimise their x-ray dose. They wear lead aprons and stand behind a lead screen or stand outside of the room and lead is used to shield parts of the patients body that isnt being scanned.
9 of 10
Why are ultrasound waves used for breaking up kidney stones?
They are vibrations in materials and it is the vibrations set up by the ultrasound waves in the kidney stones that break them up. X-rays do not cause vibrations.
10 of 10
Other cards in this set
Card 2
Front
What is an x-ray?
Back
High frequency, short wavelength electromagnetic waves which are used in hospitals for medical diagnosis, e.g. bone fractures, dental problems.
Comments
No comments have yet been made