NMTCB-CT QUESTIONS AND ANSWERS
(GRADED A+)
Where are x-rays made? - ANSWER-in the electron shell structure of an atom
What is Bremsstrahlung radiation? - ANSWER-energetic electrons pass very near the
nucleus of an atom. The strong forces of th positive charged atom causes the negatively
charged electron to decelerate; the path of the electron is changed, and some of the
kinetic energy of the electron is lost, and converted into x-rays
what is characteristic x-ray radiation? - ANSWER-following the ionization of an atom
that leaves an inner shell, outer shell electrons drop down to refill the inner shell. As
these electrons drop down, they lose energy, which is released as x-rays.
What does pre-collimation do? - ANSWER-(used before x-rays enter the patient)
defines the beam shape and width (which is usually fan or cone shaped) and protects
the patient from excess radiation
What does post-collimation do? - ANSWER-(used to reduce scatter after leaving the
patient) is used before the radiation strikes the detectors
What are advantages of thinner collimation? - ANSWER-A: less volume averaging
B: increased spatial resolution
C: decreased spatial resolution
D: fewer artifacts
E: all of the above
F: a,b,d **
True or false: in CT, the gantry rotates continuously in one direction on a slip ring
system - ANSWER-true
What is a scout imaged used for? - ANSWER-Positioning /localization
Pitch - ANSWER-the ratio of patient's movements through the gantry during one 360
degree beam rotation relative to the beam collimation (in single slice CT)
In diagnostic CT, when might a change in pitch be useful? - ANSWER-when there is a
need for faster imaging time (during trauma, inability of the patient to
comply/cooperate/tolerate scanning, CTA)
What is the kilovolt potential (kvP)? - ANSWER-determines the kinetic energy given to
the emitted electrons produced from the potential difference between the cathode and
the anode-- designates the maximum x-ray energy
(GRADED A+)
Where are x-rays made? - ANSWER-in the electron shell structure of an atom
What is Bremsstrahlung radiation? - ANSWER-energetic electrons pass very near the
nucleus of an atom. The strong forces of th positive charged atom causes the negatively
charged electron to decelerate; the path of the electron is changed, and some of the
kinetic energy of the electron is lost, and converted into x-rays
what is characteristic x-ray radiation? - ANSWER-following the ionization of an atom
that leaves an inner shell, outer shell electrons drop down to refill the inner shell. As
these electrons drop down, they lose energy, which is released as x-rays.
What does pre-collimation do? - ANSWER-(used before x-rays enter the patient)
defines the beam shape and width (which is usually fan or cone shaped) and protects
the patient from excess radiation
What does post-collimation do? - ANSWER-(used to reduce scatter after leaving the
patient) is used before the radiation strikes the detectors
What are advantages of thinner collimation? - ANSWER-A: less volume averaging
B: increased spatial resolution
C: decreased spatial resolution
D: fewer artifacts
E: all of the above
F: a,b,d **
True or false: in CT, the gantry rotates continuously in one direction on a slip ring
system - ANSWER-true
What is a scout imaged used for? - ANSWER-Positioning /localization
Pitch - ANSWER-the ratio of patient's movements through the gantry during one 360
degree beam rotation relative to the beam collimation (in single slice CT)
In diagnostic CT, when might a change in pitch be useful? - ANSWER-when there is a
need for faster imaging time (during trauma, inability of the patient to
comply/cooperate/tolerate scanning, CTA)
What is the kilovolt potential (kvP)? - ANSWER-determines the kinetic energy given to
the emitted electrons produced from the potential difference between the cathode and
the anode-- designates the maximum x-ray energy
