Production of X-rays questions
1. Regarding x-ray tubes, all of the following are true except:
a) The cathode emits electrons by thermionic emission.
b) Electrons travel from the anode to the cathode.
c) The kVp is the peak voltage applied between the anode and the cathode.
d) When electrons strike the target, characteristic x-rays and bremsstrahlung are emitted.
e) The target is angles and rotated to increase its heat capacity.
[Raphex 2007, G38]
2. The ratio of energy converted to heat vs. energy converted to x-ray production in a typical
diagnostic x-ray target is about _______.
a) 1:1000
b) 1:100
c) 1:1
d) 100:1
e) 1000:1
[Raphex 2007, G39]
3. The maximum photon energy in an x-ray spectrum is determined by:
a) The inherent and added filtration.
b) The target material.
c) The kVp.
d) The maximum mA.
e) None of the above.
[Raphex 2007, G44]
4. To produce a bremsstrahlung x-ray:
a) An orbital electron is removed.
b) An electron is slowed down by the field of the nucleus.
c) An electron is absorbed by the nucleus.
d) An electron will change shells, emitting the excess binding energy as an x-ray.
e) An electron first causes the nucleus to change to a higher energy state, which is then followed
by x-ray emission.
[Raphex 2007, G50]
5. The x-ray tube current is:
a) Determined by the anode temperature.
b) Adjusted through varying the filament current.
c) Usually space charge limited.
d) Usually 500mA for mammography tubes.
e) Higher for fluoroscopy tubes compared to that used in radiography tubes.
[Raphex 2007, D1]
6. The number of turns for the primary coils and the secondary coils of a step-up transformer are
100 and 120000, respectively. If the peak voltage of the input power to this transformer is 110 V,
the output peak voltage is ______.
a) 110 V.
b) 120 kV.
c) 132 kV.
d) 66 kV.
7. The “heel effect” in x-ray tubes
a) Represents decreasing x-ray intensity from the cathode to the anode direction of the beam.
b) Is caused by low energy photons being reflected more than high energy photons.
c) Is due to the absorption of accelerated electrons by the target.
8. The bremsstrahlung x-ray energy spectrum is approximated represented the Kramer’s equation,
which indicates that: (choose all correct statements.)
a) the maximum energy of photons is equal to the accelerating potential.
b) the intensity of photons with a specific energy increases with the square of the photon energy.
c) the intensity of photons is proportional to the atomic number of the target material.
d) the average energy of photons is 1/3 of the maximum energy.
9. The main functions of the anode hood in a therapy x-ray tube are: (choose all apply.)
a) To absorb the secondary electrons emitted from the target.
b) To absorb the x-rays produced in the anode hood.
c) To collimate the x-ray beam.
d) To collimate the electron beam bombarding the target.
10. Which is used to change the shape of alternating current (AC) used for accelerating electrons in
an x-ray tube to help increasing the average energy of x-rays? (Select one).
a) Step-up transformer.
b) Auto-transformer.
c) Rheostat.
d) Rectifier.
e) Filament.
Answers to Production of X-rays questions
1. (b)
2. (d)
3. (c)
4. (b)
5. (b)
6. (c)
7. (a)
8. (a) and (c)
9. (a) and (b)
10. (d)