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Physics Chapter 9 Bushong
Terms in this set (85)
Name the five xray interactions with matter
Structures that are similar in size to the wavelength of the radiation
Electromagnetic radiations interacts with what?
The _______ the energy of an xray the _________ the wavelength.
Longer wavelength= large diameter=interact with whole atom
Lower energy x-rays
Interact with electrons
Moderate energy x-rays
Short wavelength= small diameter= interact with largest piece of atom and electrons= nuclei
High energy x-rays
Below 10 keV
Coherent scatter typically occurs at what range?
Incident photon causes target atom to become excited, the target atom releases excess energy from excitation, the energy release is equal to that of the incident photon
Describe what happens in the coherent interaction.
In coherent scatter the direction of the photon is changed with ___________ change in energy
No, accounts at image noise (graying)
Is coherent scatter diagnostically useful?
Any energy range
What energy range can Compton scattering occur?
At what energy ranges does Compton scatter usually occur?
Atomic number of absorber (tissue)
Compton scatter is independently of what?
Incident photon interacts with the outer shell electron, ejects the outer shell electron from the atom, incident photon continues to travel in different direction
escribe the interaction of Compton scattering.
In compton the Incident photon ___________energy determined by its angle of deflection.
More energy is lost
Higher the angle of deflection =
equal to the difference between the energy of the incident x-ray photon, and the energy of the ejected electron
The energy of the Compton scattered x-ray is....
Equal to the binding energy plus the kinetic energy of the electron.
The energy of the ejected electron is.......
Absorbed by the patient or the image receptor
What happens to a scattered x-ray?
Looses all of its kinetic energy, drops into a vacant electron spot.
What happens to a Compton electron?
What is the angle of deflection?
no energy lost
0 degrees = how much energy lost?
At what degree would back scatter occur, equaling in more energy lost?
When scatter x-ray bounces back toward direction of incident
What else can cause back scatter to occur?
In very high energies what would be less likely to occur?
Higher energies are more likely to be a _____________ due to diameter of wavelength.
The probability of Compton scattering is ___________ ___________ to x-ray energy and independent of atomic number
Although necessary for imaging, Compton scattering __________ image contrast.
outer shell electrons and loosely bound electrons
Compton scattering is most likely to occur with ??
Increased penetration through tissue without interaction
With Compton scattering as the x-ray energy increases it also has...
Increased Compton scattering is relative to?
As atomic number of absorber increases it has ________ _________ on Compton scattering
As mass density of absorber increases the is a _____________ __________ in Compton scattering?
What diagnostic range does photoelectric occur?
Inner electron shell of a target atom
Where does photoelectric effect occur?
keV and atomic number of absorber
What is photoelectric dependent on?
Incident photon interacts with an inner shell electron, Incident photon is not scattered, but totally absorbed, photon ejects an inner shell electron
Describe the interaction of a photoelectric interaction.
What is a by product of photoelectric?
energy of the incident x-ray and the binding energy of the electron
The kinetic energy of a photoelectron is equal to the difference between the ........
For photoelectric effect, the probability of an interaction is __________ __________ to the third power of an energy.
For photoelectric effect, the probability of an interaction is ________ ________ to the third power of the atomic number (z)?
Name the human issue in order from highest to lowest effective atomic number.
Name the contrast material in order from highest to lowest effective atomic number.
Inner shell electrons
tightly bound electrons
when x-ray energy is just higher than electron binding energy
Photoelectric effect is most likely to occur with?
Increased penetration through tissue without interaction
Less photoelectric effect relative to Compton scattering
Reduced absolute photoelectric effect
With photoelectric interaction as x-ray energy increases there is.....
Increased proportionality with the cube of the atomic number
With photoelectric as atomic number of absorber increases, what happens?
Proportional increase in photoelectric absorption
In photoelectric as mass density of the absorber increases, what happens?
High energy photons
Pair productions occur with ???
How much MeV photon energy do you need for pair production?
Does pair production occur in diagnostic radiology?
Pair production is very important in?
No electron interaction
Photon interacts directly with nucleus
Magnetic field of nucleus interacts with incident photon
Describe the interaction in pair production.
2 electrons appear, 1 negatron and 1 positron
What happens when the incident photon disappears in pair production?
What is a by product of pair production?
Negatron fills the void of neighboring atom, positron will unite with a free electron, mass of both converts to energy.
Describe annihilation radiation
10 MeV or above
What energy level do you need for photodisentegration?
Does photodisintegration occur in diagnostic imaging?
No interaction with electrons, direct interaction with the nucleus, incident photon is directly absorbed by the nucleus, nucleus is raised to an excited state
Describe the interaction in photodisintegration
In photodisintegration the excited nucleus emits what?
Proton or neutron
What is in a nuclear fragment?
Results in different densities on a radiograph due to various amounts of x-ay that make it to the image receptor
When x-rays do not make it to the image receptor due to characteristics of the absorber
Radiopaque usually yields what effect?
When x-rays are transmitted with little to no interaction from the absorber
Radiolucent usually yields what effect?
Differential absorption is affected by what three things?
Differential absorption ______ as kVp is ________?
The quantity of matter per unit volume (kg/cm^3)
The interaction of x-rays with tissue is __________ to the mass density of the tissue reguardless of the type of interaction
Compton ans photoelectric
The two primary forms of x-ray interaction in the diagnostic range are?
An incident x-ray interacts with an atom without ionization during?
An outer shell electron is ejected and the atom is ionized during?
Which x-ray interaction involves ejection of the k-shell electron?
Compton scatter is directed at ______ angle from the incident beam.
As kVp ________, the probability of photoelectric absorption _______?
In _______, there is complete absorption of the incident x-ray photon
____________ occurs only at very high energies used in radiation therapy and in nuclear medicine.
K-shell binding energy increases with increasing ______?
Because of the differential absorption, about _____% of the incident beam from the x-ray tube contributes to the finished image.
Attenuation is caused by what two things?
Negative contrast agent?
High kVp techniques reduce?
At energies below 40 keV, the predominant x-ray interaction in soft tissue and bone is _______?
If 5% of an incident beam is transmitted through a body part, then 95% of that beam was?
THIS SET IS OFTEN IN FOLDERS WITH...
Bushong Chapter 10
Scatter Radiation (Chapter 11) Bushong
Bushong Chapter 8
Chapter 33 BUSHONG
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