State and explain one advantage of the use of high frequency ultrasound as
compared with low frequency ultrasound for medical diagnosis.
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Shorter wavelength
Smaller structures resolved / detected (not more sharpness)
Describe how the image produced by CT scanning differs from that produced
by X-ray imaging.
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X-ray image is flat or 2-D
CT scans takes many images of a slice at different angles
These build up an image of a slice through the body
Series of images of slices is made
, So that a 3D image can be built up
Image can then be rotated
State what is meant by the specific acoustic impedance of a medium.
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Product of density (of medium) and speed (of ultrasound) in the medium
What is contrast?
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The DIFFERENCE in the degree of blackening of structures in the image.
Suggest, with a reason, the effect on the linear absorption coefficient of an X-
ray beam comprised of more energetic photons.
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X-ray photons are more penetrating / μ is smaller
By reference to the formation of the image in each case, suggest why the
exposure to radiation differs between CT scans and X-rays.
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compared with low frequency ultrasound for medical diagnosis.
Give this one a try later!
Shorter wavelength
Smaller structures resolved / detected (not more sharpness)
Describe how the image produced by CT scanning differs from that produced
by X-ray imaging.
Give this one a try later!
X-ray image is flat or 2-D
CT scans takes many images of a slice at different angles
These build up an image of a slice through the body
Series of images of slices is made
, So that a 3D image can be built up
Image can then be rotated
State what is meant by the specific acoustic impedance of a medium.
Give this one a try later!
Product of density (of medium) and speed (of ultrasound) in the medium
What is contrast?
Give this one a try later!
The DIFFERENCE in the degree of blackening of structures in the image.
Suggest, with a reason, the effect on the linear absorption coefficient of an X-
ray beam comprised of more energetic photons.
Give this one a try later!
X-ray photons are more penetrating / μ is smaller
By reference to the formation of the image in each case, suggest why the
exposure to radiation differs between CT scans and X-rays.
Give this one a try later!
