Physics 2 Questions
1. Alternating electric current sources produce
(A) static electric fields
(B) static magnetic fields
(C) unidirectional flow of electrons
(D) oscillatory flows of electrons
(E) all of the above
2. Transformers in an x-ray machine
(A) work on the principle of electromagnetic induction
(B) need a filament as a source of electrons
(C) are used to transform electron energy into x-rays
(D) utilize thermionic emission
(E) cannot be used to generate low voltages
3. Match the device found in an x-ray circuit with its purpose.
(A) Transformer
(B) X-ray tube filament
(C) Diode
D) Milliammeter
(i) Allows current to flow in one direction only
(ii) Increases or decreases voltage
(iii) Thermionic emission of electrons
(iv) Measures tube current
4. Match the following waveforms with the theoretical percentage ripple.
(A) Constant potential
(B) Single phase
(C) Three phase (6 pulse)
(D) Three phase (12 pulse)
(i) 0%
(ii) 3.5%
(iii) 14%
(iv) 100%
5. Electrons passing through matter lose energy primarily by
(A) production of bremsstrahlung
(B) photoelectric interactions
(C) collision with atomic electrons
(D) Compton interactions
(E) thermionic emission
6.100 keV electrons incident on a tungsten target can produce
(A) Bremsstrahlung x-rays with a maximum energy of 100 keV
(B) Bremsstrahlung x-rays with average energy of 100 keV
(C) characteristic x-rays of 100 keV
(D) negligible (< 1%) heat in the target
(E) 100 keV photoelectrons
7. The continuous x-ray spectrum obtained from an x-ray tube is due to
(A) transitions of atomic electrons from higher to lower energy levels
(B) deceleration of electrons in the anode
(C) target heating by the electrons
(D) ejection of K-shell electrons
(E) ionization of target atoms
8. The maximum photon energy in x-ray beams is determined by the
(A) atomic number (Z) of the target
(B) atomic number (Z) of the filament
(C) voltage across the filament (V)
(D) voltage between anode and cathode (kV)
(E) tube current (mA)
9. Match the following radiations with the production parameters.
(A) Characteristic radiations of 19 keV
(B) Low energy photons have been removed by filtration
(C) Maximum photon energy is 100 keV
(D) Characteristic radiation at about 65 keV
(i) Applied x-ray tube voltage is 100 kV
(ii) X-ray tube has equivalent of 3 mm Al filtration
(iii) Anode is made of molybdenum
(iv) Anode is made of tungsten
10. The number of electrons accelerated across an x-ray tube is determined by
(A) anode speed
(B) focal spot size
(C) filament current
(D) x-ray tube filtration
(E) none of the above
11. X-ray production with a tungsten anode at 100 kVp is primarily
(A) Bremsstrahlung radiation
(B) characteristic radiation
(C) Compton scatter
(D) photoelectric
(E) none of the above
12. Anodes for production of x-rays have
(A) low atomic numbers (Z)
(B) air cooling to help dissipate their heat
(C) beryllium covering to prevent thermionic emission
(D) high-heat capacities to tolerate high temperatures
(E) all of the above
13. The line focus principle may be explained as
(A) apparent focus is smaller than true size
(B) another name for the heel effect
(C) x-ray intensity falls as square of distance
(D) reduction in intensity at anode edge
(E) all of the above
14. The size of an x-ray tube focal spot is
(A) larger than the nominal value by up to 50%
(B) dependent on applied mA ("blooming")
(C) smaller for magnification radiography
(D) measured using pinhole cameras
(E) all of the above
15. Match the focal spot size with the application.
(A) 0.1mm
(B) 0.3 mm
(C) 0.6 mm
(D) 1.Omm
(E) 1.5mm
(i) Radiography focal spot
(ii) Fluoroscopy focal spot
(iii) Magnification neuroradiography
(iv) Magnification mammography
(v) Measured large focal spot
16. The formula mA x kV x time for a constant potential x-ray generator is the
(A) maximum safe technique value
(B) total energy deposited
(C) exposure level at 1 meter
(D) focal spot loading (power)
(E) none of the above
17. Calculate the anode heat loading for the following exposures.
(A) 100 seconds of fluoroscopy @ 100 kV and 5mA
(B) Chest x-ray @ 100 kV, 1,000 mA, and 10 ms
(C) Lateral C-spine @ 100 kV, 500 mA, and 100 ms
(D) 10 s cardiac cine run @ 100 kV, 1,000 mA, 10 ms, and 50 frames per second
(E) 10s digital run @100kV, 100 mA, 10 ms, and 10 frames per second
18. Heat generated in an anode is primarily dissipated by
(A) convection
(B) conduction
(C) combustion
(D) air cooling
(E) radiation
19. True (T) or False (F).
For an x-ray tube rating of 80 kW, the following exposures (0.1 sec) would be allowed.
(A) 100kV and 800mA
(B) 100kV and 1000mA
(C) 80kVand 1000mA
D) 90kV and 900mA
20. True (T) or False (F).
The energy of an x-ray tube characteristic x-ray is
(A) proportional to the energy of the projectile electrons
(B) dependent on the shell structure of the target atom
(C) about 65 keV for tungsten anodes
(D) dependent on x-ray filtration
(E) about 19 keV for molybdenum anodes
21. Changing the x-ray tube current (mA) is most likely to modify which of the following x-ray beam parameters?
(A) Maximum energy
(B) Quantity
(C) Quality
(D) Patient penetration (%)
(E) All of the above
22. Increasing the x-ray tube kVp will result in an increase of the average x-ray
(A) velocity
(B) wavelength
(C) energy
(D) mass
(E) none of the above
23. X-ray beam quality is primarily determined by
(A) focal spot size
(B) filament current
(C) x-ray tube current
(D) filament voltage
(E) x-ray tube voltage
24. True (T) or False (F).
The heel effect is more pronounced
(A) closer to the focal spot
(B) at high mA
(C) with a small target angle
(D) perpendicular to the anode-cathode anode axis
(E) at the anode edge of the x-ray field
25. Match the following types of radiation with the appropriate definition.
(A) The useful beam
(B) Secondary radiation
(C) Stray radiation
(D) Leakage radiation
(E) Scattered radiation
(i) Radiation transmitted through the x-ray tube housing
(ii) Primary radiation limited by the collimator
(iii) Radiation changed in direction
(iv) Radiation resulting from absorption of other radiation
(v) Sum of the leakage and scattered radiation