Also
Type of scattered photons that have essentially the same energy as the incoming, or “incident,” photons.
What is small-angle scatter?
scatter interaction that occurs at energies less than 10 keV and between 1-50 kVp
What is Coherent (Classical, Thompson, elastic, unmodified) scatter?
by-product of photoelectric interactions
What is a photoelectron (characteristic photon)?
electron shell involved in Compton interactions
What are outer-shell electrons?
Aluminum
What is 13?
Additional, undesirable exposure of the IR from small-angle scatter that degrades the appearance of a completed radiographic image by blurring the sharp outlines of dense structures
What is radiographic fog?
formula to determine the energy of the photoelectron
What is the energy of the incident photon minus the binding energy of the electron shell?
What is K-shell?
two interactions that are of most significance in diagnostic radiography
What are photoelectric and compton scattering?
Barium
What is 56?
Primary method to reduced radiographic fog
What is collimation?
*a.k.a limiting the amount of tissue irradiated*
two by-products of photoelectric absorption
What are photoelectrons and characteristic x-ray photons?
Interaction responsible for patient dose and contrast in the image
What is photoelectric absorption?
_________________ occurs as an electron from a higher shell drops down and fills the vacancy in the inner shell by releasing energy as a ___________ (2 part answer)
What is the characteristic cascade and a characteristic photon?
Lead
What is 82?
this energy transfer results in increased patient absorbed dose and does not contribute to the radiographic image
What are photoelectric interactions?
two variables that influence the probability of photoelectric absorption
What are the energy of the incident x-ray photons and the atomic number of the irradiated object?
simplest and best ways of reducing patient dose through technique adjustment
What is increase kVp?
This higher energy will lead to a slight but still acceptable lessening of image contrast because of a decrease in the amount of photoelectric interactions at the higher beam energy
the ejected outer-shell electron after Compton interactions is now called
What is Compton (secondary, recoil) electron?
Iodine
What is 53?
5 types of interactions between x-ray photons and matter
What are Coherent scattering, Photoelectric absorption, Compton scattering, Pair production, and Photodisintegration?
probability of photoelectric absorption increases as the energy of the incident photon ___________ and the atomic number of the irradiated atoms ____________
What is decreases and increases?
for equal thicknesses of bone and soft tissue, bone will absorb ____________ times as many x-ray photons as soft tissue in the diagnostic energy range
What is 13?
dependent on mass density and atomic number
bone is 2x as dense as soft tissue, would absorb twice as much radiation due to the density difference alone.
bone would also absorb 6.5 times as much radiation because of the difference in effective atomic numbers since (13.8)^3 / (7.4)^3 = 6.5
Final probability: 6.5(Z#) x 2(density)=13
incident x-ray photon that surrendered some of its energy to free the loosely bound outer-shell electron from its orbit in Compton interactions continues on its way, but in a new direction, and is now called a
What is a Compton scattered photon?
Molybdenum
What is 42?