ch. 4
ch. 4
ch. 4
Ch. 12 starts
ch. 12

100

A photon with just slightly more energy than the electron binding energies of the tissue through which it passes is most likely to undergo what type of interactions?
Photoelectric

100

How much thicker does the anatomical part need to be in order to absorb twice as much of the x-ray beam?
4cm

100

If barium causes just as many Compton scatter interactions as normal fluids in the stomach, why does it show up white?
It has an atomic number of 56, so it can absorb a large number of x-rays.

100

What interaction causes the most image fog?
Compton

100

What happens to the mAs when there is a 4cm DECREASE in thickness?
Half the mAs

200

Roughly how much of the radiation STRIKING THE IMAGE RECEPTOR is secondary radiation?
75%

200

A photon is completely absorbed by an inner-shell orbital electron in the patient, and the electron ejects from its orbit. Name this interaction.
Photoelectric effect

200

What is the end product of Compton interaction?
Compton electron, secondary electron, and Compton scatter photon.

200

In bone, which interaction is more prevalent at very low kVp levels?
Photoelectric effect

200

What happens to the mAs when for every 4cm increase in thickness?
Double the mAs.

300

Which two interactions within the patient result in scatter radiation? Which one has the greatest?
Compton & Thompson Compton has 99%

300

A photon with much more energy than the electron binding energies of the tissue through which it passes is most likely to undergo what type of interaction?
Compton

300

Name two interactions in the patient that ionize atoms
Photoelectric and Compton

300

How is the attenuation increased with tissue thickness?
Exponentially

300

Define tissue density
The physical density of a substance is the amount of physical mass that is concentrated in a given area.

400

Which interaction contributes most to image contrast?
Photoelectric

400

A photon w/ slightly more energy than the electron binding energies of the tissue through which it passes is most likely to undergo what type of interaction?
Photoelectric effect

400

Name two interactions in the patient that cause scatter radiation
Thompson and Compton

400

How is tissue thickness described in relation to attenuation?
As the tissue area becomes thicker, the amount of attenuation is greater.

400

What happens to attenuation when the tissue density is higher?
greater attenuation

500

In bone, which interaction is more prevalent at very low kVp levels?
Photoelectric

500

How do bone molecules differ from soft tissue?
Bone is more physically dense and the atomic number is a notable difference.

500

What interaction contributes the most to subject contrast?
Photoelectric effect

500

What is the average thickness of the abdomen?
22cm

500

What happens to attenuation when the tissue density is lower?
Less attenuation