Types of interactions and Photoelectric Effect
Compton and Thompson Effects
Thompson Effect and other interactions
Types of Radiation and Subject Contrast
Subject contrast cont.

100

What are the three main types of x-ray interactions that occur within the patient?
Photoelectric effect, Compton effect, and Thompson effect

100

What are two other names for the Compton Effect?
Modified scattering and incoherent scatters

100

The Thompson effect is responsible for what percentage of scatter?
1%

100

Define secondary radiation
Any radiation resulting from interactions within the body

100

If you increase tissue thickness, tissue density, and/or tissue atomic number, what will happen?
Increase in scatter, longer gray scale, less blacks and whites

200

What is the photoelectric effect responsible for?
The photoelectric effect produces the contrast on the images

200

The Compton Effect is responsible for what percentage of the scatter?
99%

200

At what kVp does the Thompson effect occur at?
70 kVp and above

200

Define remnant radiation
Radiation emitted in the direction of the primary beam

200

What happens to contrast, gray scale, wavelength, and penetration when kVp is increased?
decreased contrast long gray scale shorter wavelength greater penetration

300

The photoelectric effect is responsible for what colors on the image?
All blacks and whites

300

What kVp does the Compton Effect occur at?
70 kVp and above

300

Describe the Thompson effect
The photon has less energy than the electron it interacts with, hence increasing the energy of the electron, which is released as a scatter photon

300

Define scatter radiation
Radiation emitted in a direction that differs from its' original direction

300

What effect does increasing the x-ray beam energy (kvp) have on the proportion of Compton scatter interactions compared to photoelectric interactions?
Compton Effect is increased and Photoelectric effect is decreased

400

What must the kVp be for photoelectric effect to occur?
<70 kVp

400

Describe the Compton Effect
Produces a recoil electron and a Compton photon when the incoming photon has more energy than the electron in an outer shell

400

What is a vague description of the other interactions?
Can produce characteristic interactions similar to that which occurs in the anode

400

What has the greatest influence over "overall contrast"
Absorption

400

What effect does increasing the x-ray beam energy (kVp) have on the total number of all interactions within the patient?
Decreases

500

Describe the photoelectric effect
When the photon is absorbed by an inner-shell electron, which then increases it's energy to the point the electron is ejected out as a photoelectron. The photoelectron then collides with another atom and never leaves the body.

500

What are 3 other names for the Thompson effect?
unmodified scattering, coherent scattering, and classical scattering.

500

What are two examples of other interactions?
Pair production and photodisinegration

500

What are the three factors in subject contrast?
Tissue thickness, tissue density, tissue atomic number

500

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