Unit 2 Jeopardy and Quiz questions: Flashcards
Which of the following is NOT an interaction that takes place at the anode target:
compton scatter
photoelectric
coherent scatter
photoelectric
The incident x-ray interacts with an atom without ionzing during:
coherent
Which has the greatest mass density?
bone
As kVp _________ the probability of photoelectric absorption _________
increases, decreases
Barium is a good contrast agent because of its:
high atomic number
Compton interactions, photoelectric absorption and transmitted x-rays all contribute to:
differential absorption
Which of the following is the easiest to penetrate?
bone
muscle
fat
water
fat
Increasing x-ray energy will result in:
fewer average photoelectric interactions
Which interactions involve the process of ionization?
Brems
Characteristic
Coherent scatter
Compton scatter
Photoelectric effect
characteristic
compton scatter
photoelectric effect
What is produced as a result of pair production?
two electrons: one positive and one negative
What are the other two names for Coherent scatter?
Classical and Thompson
What type of technique setting is most likely to produce a greater amount of forward scatter?
high kVp
Increased filtration has what effect on subject contrast?
decreases it
What is the name of the radiation that is produced inside the pt as a result of the photoelectric effect?
secondary radiation
Filtration has what effect on image contrast? Why?
increasing filtration decreases contrast bc photons that could contribute to contrast are filtered out
What two factors determine the trajectory of a Compton scattered photon?
interaction w/ valence electron
keV of photon
Decreases in kVp have what effect on the total amounts/percentages of Compton scatter?
decreases the overall interactions, but percentages of Compton increases
What is the controlling factor of subject contrast?
kVp
Which is more difficult to penetrate? Muscle or fat?
muscle
A photon entering the body with 9 keV, after scattering, will produce a Coherent scatter photon with what keV value?
9 keV (same energy in, same out)
What must the keV value of the incident photon be, in order for the photoelectric effect to occur?
must be = to or slightly greater than the keV of the valence electron
Decreases in kVp have what effect on the total amounts/percentages of photoelectric absorption?
total amount of absorption decreases, absorption percentages increase
List the 8 factors of image contrast:
SID
OID
filtration
collimation
computer processing (LUT)
kVp
grids
scatter
Name two differences between Compton and Coherent scatter:
Compton ionizes and transfers energy which contributes to dose, Coherent does not
What are the two names used to describe an electron that has been removed through ionization during a Compton event?
recoil or Compton electron
Photons that interact with matter by way of coherent scattering usually possess a keV of less than what?
10 keV
What are the four factors that affect the likelihood of the photoelectric effect?
kVp
body part thickness
body part density
atomic number of tissue
Why is coherent scatter not a cause for concern when it comes to image contrast?
they rarely make it to the IR due to them being low in energy, so they barely contribute to noise
What is the term for the overall reduction in image contrast that is caused by Compton scatter?
noise
Which type of Compton scatter is the main source of occupational dose?
side
List three factors that would lead to high subject contrast:
low kVp
thicker part
increased part density
high Z-number anatomy
How would you define an “attenuated photon”
doesn’t reach the IR
Why does an increase in kVp create more image noise due to Compton scatter?
bigger beam and greater amount of forward scatter
What name do we use to refer to an electron that has been ionized through the process of the photoelectric effect?
photoelectron
Name an exam that the “air gap” technique can be used to improve image contrast:
cross table hip
What process produces subject contrast?
differential absorption
kVp is the controlling factor for what?
subject contrast
What is the most effective way to reduce the loss of image contrast caused by Compton scatter?
increase collimation
What is the controlling factor for image contrast?
LUT
Why is Compton scatter just as likely to occur in bone as it is in soft tissue?
electron density (increase in water)
