X-Ray Interactions Flashcards
What is the process called when an X-ray beam passes through matter?
Attenuation
Attenuation involves the interaction of X-ray photons with matter, leading to energy loss.
Which part of the atom does the X-ray photon primarily interact with in diagnostic imaging?
Orbital electrons
Interactions with orbital electrons are predominant in diagnostic imaging.
What is the term for the energy required to remove an electron from its orbit?
Binding energy
Binding energy varies by electron shell and is specific to each atom.
Which shell of electrons possesses the highest binding energy?
K-shell
K-shell electrons are more tightly bound in high-atomic-number elements.
What happens when an outer shell electron moves into an inner shell?
It releases energy equal to the difference between the binding energies of the two shells
This process is known as characteristic radiation.
List the 3 (of 5) basic interactions between X-rays and matter.
- Photoelectric absorption
- Coherent scattering
- Compton scattering
(Not highlighted) - Pair production
- Photodisintegration
What occurs during photoelectric absorption?
An incident photon ejects a K-shell electron and is totally absorbed
The result is an ionized atom and a photoelectron.
What are the conditions for a photoelectric interaction to occur?
- Incident photon energy must be greater than binding energy
- Photon energy should be slightly greater than binding energy
- More likely with tightly bound electrons in high atomic number elements
What is Compton scattering?
Incident photons interact with loosely bound outer shell electrons, resulting in a recoil electron and a scattered photon
Compton scattering is a significant source of occupational radiation exposure.
What is the primary cause of occupational radiation exposure?
Scatter radiation
Scatter radiation contributes unwanted exposure to images, referred to as radiation fog.
What is coherent scattering?
Occurs between very low energy X-ray photons and matter, resulting in a scatter photon without ionization
Coherent scattering includes Thompson and Rayleigh types.
What are the effects of increasing kVp on X-ray interactions?
- Increases total number of photons transmitted without interaction
- Decreases overall attenuation
- Greater percentage of scattered photons than absorbed photons
Higher energy leads to a shift in interaction dynamics.
What happens during pair production?
The energy of the X-ray photon is converted to matter in the form of two electrons
Requires a photon energy of at least 1.02 MeV.
True or False: Photoelectric absorption predominates in lower energy ranges (40-70 kVp).
True
Photoelectric absorption is more likely in low energy ranges and in high atomic number elements.
Fill in the blank: The ionized atom produced during photoelectric absorption is _______.
unstable
The ionization creates a vacancy that must be filled by another electron.
