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 electro...
NMTCB-CT questions with correct answers
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)
The table distance traveled in 1 gantry rotation of 360o divided by the total thickness of all acquired slices—in multi detector CT
How is pitch calculated? Answer ✓✓ pitch = table movement per rotation (mm)/ (number of slices)(slices width in mm)
What happens when pitch is decreased? Answer ✓✓ --the number of views per linear scan distance increases,
--spatial resolution is increased
--noise decreases
--exposure is also increased
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
What happens as the kVp is increased? Answer ✓✓ --the penetration energy of the x-rays is increased
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