Chapter 10 (X-Ray Interactions with Matter) Flashcards
What are the five x-ray interactions with matter?
Coherent scattering, Compton scattering, Photoelectric effect, Pair production, Photodisintegration.
What x-ray interaction is responsible for image contrast?
Photoelectric effect.
What interaction is the primary cause of scatter radiation?
Compton scattering.
What happens in Compton scattering?
A photon interacts with an outer-shell electron, ejecting it and scattering the photon.
What happens in the photoelectric effect?
A photon interacts with an inner-shell electron, ejecting it and getting completely absorbed.
What is the relationship between atomic number (Z) and photoelectric effect?
Higher Z = More photoelectric interactions.
How does increasing kVp affect photoelectric interactions?
Decreases photoelectric effect, reducing contrast.
What interaction occurs at x-ray energies >1.02 MeV?
Pair production.
What interaction occurs at x-ray energies >10 MeV?
Photodisintegration.
What does Compton scatter do to image contrast?
Reduces contrast by adding fog.
What happens to patient dose when the photoelectric effect increases?
Patient dose increases due to greater absorption.
What is the primary source of occupational radiation exposure?
Compton scatter.
Why do contrast agents like barium improve x-ray imaging?
They enhance the photoelectric effect, increasing contrast.
How does collimation affect scatter radiation?
Reduces scatter, improving image contrast.
What does differential absorption depend on?
X-ray energy and atomic number of the tissue.
What is an annihilation reaction?
A positron and electron collide, producing two 0.51 MeV photons.
What is the main difference between Compton and photoelectric interactions?
Photoelectric results in total absorption, Compton results in scattering.
What happens to scatter radiation as kVp increases?
Scatter radiation increases.
What is backscatter radiation?
Scatter radiation that is deflected 180° back toward the source.
What is the best way to reduce scatter radiation?
Use grids and collimation.
