5.4.1 X-RAYS

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Describe the nature of X-rays
EM waves/ travel at speed of light/ travel in a vacuum/ can cause ionisation/ wavelength of about 10'-10m/ high energy photons
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Describe the production of X-rays
cathode to anode/ electrons accelerated through high voltage towards target metal when they smash into it they decelerate and small amount of the KE is converted into X-rays
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How is the production of X-rays maximised?
good vacuum/ cathode heated to increase output/ anode shaped to beam focused/ tube is surrounded by lead shielding
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Name the ways in which X-rays interact with matter
Photoelectric effect/ compton scattering/ pair production
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Describe the X-ray photoelectric effect
photon disappears and its energy is used to eject an electron from he target metal (low energy photons)
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Describe X-ray compton scattering
mid energy photon/ collides with orbital electron/ electron ejected only absorbing some energy form photon/ scattered photon leaves at different angle
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Describe X-ray pair production
high energy/ interacts with nucleus/ electron-positron pair released/ when position annihilated by electron, two identical low energy photons produced
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Define intensity, what is it's unit?
power per cross-sectional unit area, Wm'-2
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Describe the intensity of a X-ray as it travels through a medium
inverse square law/ decreases in intensity as it interacts with materials atoms/
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Describe the use of X-rays in imaging internal body structures and the use of image intensifiers
attenuated (ABSORBED AN SCATTERED) by different amounts by different mediums/ different intensities at detector form image/ X-rays collimated to have a parallel beam with constant I
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Describe the use of contrast mediums
ie barium makes soft tissue more visible/ patient swallows liquid high in barium as it will readily absorb rays/ coats the internal wall of instant tract enabling its outline to be seen
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What is a CAT scanner?
computerised axial tomography/ produce 2D image of a slice through the body/ can also produce 3D/ X-ray beam rates around the body and is picked up by thousands of detectors
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Describe the operation of a CAT scanner
...
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What are the advantages of CAT scans?
much higher quality than X-rays as no overlap/ can produce 3D images/ can distinguish between different tissues
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What are the disadvantages of X-rays and CAT scans
both result in patient having a high dose of radiation
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Other cards in this set

Card 2

Front

Describe the production of X-rays

Back

cathode to anode/ electrons accelerated through high voltage towards target metal when they smash into it they decelerate and small amount of the KE is converted into X-rays

Card 3

Front

How is the production of X-rays maximised?

Back

Preview of the front of card 3

Card 4

Front

Name the ways in which X-rays interact with matter

Back

Preview of the front of card 4

Card 5

Front

Describe the X-ray photoelectric effect

Back

Preview of the front of card 5
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