Quiz on Physics of Radiation PDF

1. Which of the following is not considered a force? A. Electrostatic B. Weak C. Strong D. Gravity E. Electricity Electricity is the flow of charge, and is measures in amps (C/s) 2. Which of the following is not a unit of energy? A. Erg...

1. Which of the following is not considered a force? A. Electrostatic B. Weak C. Strong D. Gravity E. Electricity Electricity is the flow of charge, and is measures in amps (C/s) 2. Which of the following is not a unit of energy? A. Erg B. Joule C. Watt D. Calorie E. eV The watt is a unit of power, measured in J/s 3. Which of the following would most likely be attracted to an anode? A. Proton B. Neutron C. Electron D. Positron E. Aloha particle An electron has a negative charge that is attracted to the positive anode 4. Which quantity is the best measure of power? A. Joule B. Tesla C. Watt D. Coulomb E. Newton Watt is a unit of power, where 1 W = 1 J/s 5. Which of the following is/are likely to have the longest wavelength? A. Gamma rays B. Microwaves C. Radio waves D. Ultraviolet E. Visible light Radio waves have the lowest frequencies and longest wavelengths 6. For electromagnetic radiation, which increases with increasing photon energy? A. Wavelength B. Frequency C. Velocity D. Charge E. Mass The frequency is directly proportional to photon energy 7. If the-2 distance from a radiation source is halved, the radiation intensity increases by a factor of: A. 2-1 B. 20 C. 2+1 D. 2+2 E. 2 Halving the distance quadruples the radiation intensity (inverse square law). 8. X-ray generators have a power level (kW) of approximately: A. 0.1 B. 1 C. 10 D. 100 E. 1000 100 kW is typical of the power of x-ray generators in radiography and CT. 9. Which of the following is not a type of x-ray generator? A. Single phase B. Double phase C. Six pulse D. Twelve pulse E. High frequency There are no double phase generators. 10. The purpose of x-ray transformers is most likely to change the: A. Magnetic field B. Electrical voltage C. Power level D. Waveform frequency E. Current intensity Transformers change (increase or decrease) voltages 11. When a secondary coil has 500 more turns than a primary coil, the ratio of the secondary voltage to the primary voltage is most likely: A. 5000.5 B. 500 C. 1/5000.5 D. 1/500 E. Depends on AC frequency The increase in voltage is directly proportional to the increase in the number of turns 12. Which of the following generators is likely to have the largest waveform ripple? A. Constant potential B. High frequency C. Single phase D. Six pulse E. Twelve pulse The ripple on a single phase generator is 100% 13. Electrons passing through matter lose energy primarily by producing: A. Bremsstrahlung B. Characteristic x-rays C. Atomic ionizations D. Compton electrons E. Photoelectrons Electrons lose most of their kinetic energy by knocking out (or exciting) outer shell electrons 14. Tungsten is most likely used as an x-ray target because it has a high: A. Physical density B. Electron density C. Electrical resistance D. Melting point E. Ionization potential Tungsten can tolerate very high temperatures, which makes it an attractive target material in X-ray tubes. 15. The maximum photon energy in x-ray beams is determined by the X-ray tube: A. Current B. Exposure time C. Target material D. Anode-cathode voltage E. Total filtration The voltage across the X-ray tube determines the kinetic energy imparted to the electrons that are accelerated from the cathode (filament) to the anode (target) and thereby the maximum x-ray photon energy. The chest x-ray unit will use a W target, the characteristic energy is therefore ~65 keV 16. At 65 kV and with a tungsten target, the percentage (%) of K-shell x-rays in the x-ray beam is most likely:  A. 0 B. 1 C. 10 D. 50 E. 99 There will be no characteristic x-rays as the electron kinetic energy (65 keV) is insufficient to eject W K-shell electrons that have a binding energy of 70 keV. 17. The average photon energy of an x-ray beam is least likely to be affected by changes in the: A. Tube current B. Tube voltage C. Voltage waveform D. Target composition E. Beam filtration The tube current does not affect the average (or maximum) photon energy in x-ray beams 18. The number of electrons accelerated across an X-ray tube is most strongly influenced by: A. Anode speed B. Focus size C. Filament current D. Tube filtration E. Tube voltage The filament current affects the temperature of the filament and thereby how many electrons the filament bubbles off. 19. The most likely X-ray tube filament current (mA) is: A. 0.4 B. 4 C. 40 D. 400 E. 4000 X-ray tube filaments are about 4A, or 4000 mA. 20. The larger focus dimension is most likely larger (%) than that of the small focus by: A. 10 B. 25 C. 50 D. 75 E. 100 The large focal spot is typically 1.2 mm and the small focal spot is 0.6 mm (100% larger). 21. The anode angle (degrees) in an X-ray tube used for chest radiography is most likely: A. 15 B. 30 C. 45 D. 60 E. 75 15 degrees is a typical anode angle. 22. X-ray tube output would likely increase the most when increasing the X-ray tube: A. Voltage B. Anode angle C. Target Z D. Current E. Exposure time The X-ray tube output is (approximately) proportional to the square of the X-ray tube voltage. 23. A chest x-ray examination on a dedicated chest unit would be least likely to use: A. 60 kV voltage B. 800 mA tube current C. 10 ms exposure time D. 1 mm focus E. 5 mm Al filtration Chest x-rays are performed at high voltage (120 kV) 24. For specification of anode heat capacities, one heat unit corresponds to energy (J) of: A. 0.9 B. 0.8 C. 0.7 D. 0.5 E. 0.3 The heat unit is 0.7 joule, and is an anachronism in modern radiology. 25. At the same peak voltage, which generator likely deposits most energy into an anode? A. Constant potential B. High frequency C. Three phase (12 pulse) D. Three pulse (6 pulse) E. Single phase Since it has negligible ripple and the voltage across the X-ray tube is always the maximum possible value. 26. Heat stored in X-ray tube anodes is most likely dissipated by: A. Convection B. Conduction C. Radiation D. Air cooling E. Oil cooling Anodes get to be white hot and lose energy by radiation (light) to the tube housing. 27. In a standard X-ray tube, the maximum power loading (kW) on the 0.6mm focal spot is most likely: A. 1 B. 2 C. 5 D. 10 E. 25 The small focal spot can tolerate power levels of 25 kW (higher power would require the large focal spot) 28. Radiation transmitted through the X-ray tube housing is referred to as: A. Useful B. Secondary C. Stray D. Leakage E. Scattered Leakage radiation escapes through a fully closed collimator (the regulatory limit in the US is