RADIATION PHYSICS

focus on CH 4-7 of the Bushong radiologic physics

What is the primary function of the x-ray tube?

Which component of the x-ray tube is negatively charged?

A. Cathode | B. Anode | C. Rotor | D. Stator /// Answer: A

Which component of the x-ray tube is positively charged?

A. Filament | B. Focusing cup | C. Anode | D. Cathode /// Answer: C

What is the purpose of the focusing cup?

A. To accelerate electrons | B. To focus electrons toward the focal spot | C. To produce x-rays | D. To absorb scatter radiation /// Answer: B

What is the source of electrons in an x-ray tube?

A. Filament | B. Target | C. Anode | D. Rotor /// Answer: A

What is the function of the anode?

A. Produce electrons | B. Focus electrons | C. Receive electrons and convert their energy into x-rays | D. Heat the filament /// Answer: C

Which material is commonly used as the target material in the anode?

A. Copper | B. Aluminum | C. Molybdenum | D. Tungsten /// Answer: D

What is the main advantage of tungsten as a target material?

A. High atomic number and high melting point | B. Low atomic number | C. Low melting point | D. Poor heat resistance /// Answer: A

Which factor primarily controls the quantity of x-rays produced?

A. mAs | B. SID | C. Filtration | D. Grid ratio /// Answer: A

Which factor primarily controls the quality or penetrating ability of the x-ray beam?

A. mA | B. Exposure time | C. Distance | D. kVp /// Answer: D

What does mAs primarily control?

A. X-ray quantity | B. X-ray quality | C. Beam energy | D. Wavelength only /// Answer: A

What does kVp primarily control?

A. Exposure time | B. X-ray energy and beam quality | C. Tube current only | D. Focal spot size only /// Answer: B

Which interaction is primarily responsible for producing scattered radiation in diagnostic radiography?

A. Pair production | B. Photodisintegration | C. Coherent scattering | D. Compton scattering /// Answer: D

Which interaction contributes most to subject contrast in diagnostic radiography?

A. Compton scattering | B. Photoelectric absorption | C. Pair production | D. Photodisintegration /// Answer: B

Which interaction involves complete absorption of the incident x-ray photon?

A. Compton scattering | B. Photoelectric absorption | C. Coherent scattering | D. Pair production /// Answer: B

Which interaction results in a scattered photon with reduced energy?

A. Photoelectric absorption | B. Compton scattering | C. Pair production | D. Photodisintegration /// Answer: B

What is the minimum energy required for pair production?

A. 0.511 MeV | B. 0.75 MeV | C. 1.02 keV | D. 1.02 MeV /// Answer: D

Which process occurs when an electron and positron annihilate?

A. Photoelectric absorption | B. Compton scattering | C. Coherent scattering | D. Annihilation /// Answer: D

What type of radiation is produced when an electron changes from a higher energy shell to a lower energy shell?

A. Bremsstrahlung | B. Compton radiation | C. Characteristic radiation | D. Annihilation radiation /// Answer: C

X-rays are produced through a process called:

A. Classical scattering | B. Pair production | C. Photoelectric absorption | D. Photodisintegration /// Answer: A

What type of radiation results from the sudden deceleration of electrons near the nucleus?

A. Characteristic radiation | B. Compton radiation | C. Bremsstrahlung radiation | D. Coherent radiation /// Answer: C

Which type of x-ray radiation produces a continuous spectrum?

A. Characteristic radiation | B. Coherent radiation | C. Compton radiation | D. Bremsstrahlung radiation /// Answer: D

Which factor determines the maximum energy of a bremsstrahlung photon?

A. kVp | B. mAs | C. SID | D. Filtration /// Answer: A

What is the unit of tube current?

A. Volt | B. Ohm | C. Watt | D. Ampere /// Answer: D

What is the unit of electrical potential?

A. Ampere | B. Ohm | C. Watt | D. Volt /// Answer: D

What is the unit of electrical resistance?

A. Ampere | B. Volt | C. Ohm | D. Watt /// Answer: C

What is the unit of electrical power?

A. Volt | B. Watt | C. Ohm | D. Ampere /// Answer: B

Which component increases the voltage supplied to the x-ray tube?

A. Step-down transformer | B. Autotransformer | C. Rectifier | D. Step-up transformer /// Answer: D

Which transformer decreases voltage and increases current?

A. Step-up transformer | B. Autotransformer | C. Step-down transformer | D. High-voltage transformer /// Answer: C

Which transformer is used to adjust the voltage applied to the primary circuit?

A. Autotransformer | B. Step-up transformer | C. Step-down transformer | D. Filament transformer /// Answer: A

Which component converts alternating current into direct current?

A. Transformer | B. Generator | C. Rectifier | D. Autotransformer /// Answer: C

What is the primary function of a rectifier?

A. Increase voltage | B. Decrease voltage | C. Increase current | D. Allow current to flow in only one direction /// Answer: D

What type of rectification allows current to flow during only one-half of the AC cycle?

A. Full-wave | B. Half-wave | C. Three-phase | D. High-frequency /// Answer: B

What type of rectification allows current to flow during both halves of the AC cycle?

A. Half-wave | B. Full-wave | C. Single-phase | D. Self-rectification /// Answer: B

Which generator provides the most constant voltage to the x-ray tube?

A. Single-phase | B. Three-phase | C. Half-wave | D. High-frequency /// Answer: B

Which generator is generally the most efficient?

A. Single-phase | B. Half-wave | C. Three-phase | D. High-frequency /// Answer: D

What is the primary purpose of the filament transformer?

A. Reduce voltage and increase current | B. Increase voltage | C. Rectify current | D. Control kVp /// Answer: A

What happens to the filament when mA is increased?

A. It becomes hotter | B. It becomes colder | C. It stops emitting electrons | D. Its voltage decreases to zero /// Answer: A

The process of releasing electrons from a heated filament is called:

A. Rectification | B. Ionization | C. Bremsstrahlung | D. Thermionic emission /// Answer: D

Which device controls the amount of current flowing through the filament?

A. mA selector | B. kVp selector | C. Rectifier | D. Autotransformer /// Answer: A

Which circuit controls the quantity of x-rays?

A. High-voltage circuit | B. Filament circuit | C. Primary circuit | D. Rotor circuit /// Answer: B

Which circuit controls the speed of the rotating anode?

A. Filament circuit | B. Stator circuit | C. High-voltage circuit | D. Primary circuit /// Answer: B

What is the function of the stator?

A. Produce x-rays | B. Rotate the anode | C. Heat the filament | D. Focus electrons /// Answer: B

What is the function of the rotor?

A. Rotate the anode | B. Heat the filament | C. Produce electrons | D. Rectify current /// Answer: A

Which part of the rotating anode actually rotates?

A. Stator | B. Rotor | C. Filament | D. Focusing cup /// Answer: B

What is the purpose of rotating the anode?

A. Increase electron production | B. Increase kVp | C. Reduce filament heating | D. Spread heat over a larger area /// Answer: D

What is the focal spot?

A. The area of the target struck by electrons | B. The entire anode | C. The filament | D. The focusing cup /// Answer: A

What is the main advantage of a small focal spot?

A. Improved spatial resolution | B. Increased heat capacity | C. Increased scatter | D. Reduced contrast /// Answer: A

What is the main disadvantage of a small focal spot?

A. Lower heat capacity | B. Increased scatter | C. Lower spatial resolution | D. Increased patient dose /// Answer: A

The line-focus principle allows:

A. A large actual focal spot and large effective focal spot | B. A small actual focal spot and large effective focal spot | C. A large actual focal spot and small effective focal spot | D. No focal spot /// Answer: C

What is the anode heel effect?

A. Variation in x-ray intensity across the beam | B. Increase in focal spot size | C. Decrease in kVp | D. Increase in exposure time /// Answer: A

Where is x-ray intensity greatest because of the anode heel effect?

A. Cathode side | B. Anode side | C. Center only | D. Outside the field /// Answer: A

Which side of the patient should receive the thicker anatomy when using the anode heel effect?

A. Anode side | B. Center | C. Cathode side | D. Either side /// Answer: C

What happens to x-ray intensity as distance from the source increases?

A. It increases | B. It remains constant | C. It decreases | D. It doubles /// Answer: C

Which law explains the relationship between radiation intensity and distance?

A. Ohm's law | B. Joule's law | C. Charles' law | D. Inverse square law /// Answer: D

According to the inverse square law, if the distance is doubled, radiation intensity becomes:

A. Twice as much | B. One-fourth as much | C. Four times as much | D. Half as much /// Answer: B

What is the primary purpose of filtration?

A. Increase patient dose | B. Increase scatter | C. Remove low-energy photons | D. Increase focal spot size /// Answer: C

What type of current is used in the x-ray tube?

A. Alternating current only | B. Direct current | C. Mechanical current | D. Equipment current /// Answer: B

Which device changes mechanical energy into electrical energy?

A. Motor | B. Transformer | C. Generator | D. Rectifier /// Answer: C

Which device changes electrical energy into mechanical energy?

A. Transformer | B. Rectifier | C. Generator | D. Motor /// Answer: D

What is the main purpose of the exposure timer?

A. Control kVp | B. Control focal spot size | C. Control filtration | D. Control exposure duration /// Answer: D

Which exposure factor has the greatest effect on receptor exposure?

A. SID | B. OID | C. mAs | D. Grid ratio /// Answer: C

If mAs is doubled, receptor exposure will approximately:

A. Decrease by half | B. Remain unchanged | C. Double | D. Quadruple /// Answer: C

If kVp is increased, the x-ray beam generally becomes:

A. Less penetrating | B. Lower energy | C. More penetrating | D. Completely absorbed /// Answer: C

What is the 15% rule?

A. A 15% increase in kVp approximately doubles receptor exposure | B. A 15% decrease in kVp doubles exposure | C. A 15% increase in mAs halves exposure | D. A 15% increase in SID doubles exposure /// Answer: A

What is the primary purpose of collimation?

A. Reduce patient dose and scatter radiation | B. Increase scatter | C. Increase field size | D. Increase focal spot size /// Answer: A

Which device converts electrical energy to mechanical energy?

A. Generator | B. Transformer | C. Rectifier | D. Motor /// Answer: D

Which component provides resistance in an electrical circuit?

A. Resistor | B. Transformer | C. Generator | D. Rectifier /// Answer: A

What is the primary purpose of a capacitor in an x-ray circuit?

A. Produce x-rays | B. Store electrical energy | C. Rotate the anode | D. Filter radiation /// Answer: B

Which type of transformer has a greater number of turns on its secondary coil?

A. Step-down transformer | B. Filament transformer | C. Autotransformer | D. Step-up transformer /// Answer: D

What is the relationship between voltage and current in an ideal transformer?

A. They always increase together | B. Voltage and current are independent | C. When voltage increases, current decreases | D. Both remain constant /// Answer: C

What is the purpose of the high-voltage transformer?

A. Heat the filament | B. Rotate the anode | C. Control exposure time | D. Increase voltage to the x-ray tube /// Answer: D

Which factor primarily affects radiographic density/receptor exposure?

A. SID | B. OID | C. mAs | D. Focal spot /// Answer: C

What happens to image contrast when kVp is increased significantly?

A. Contrast increases | B. Contrast remains unchanged | C. Contrast generally decreases | D. Contrast becomes zero /// Answer: C

Which factor primarily affects spatial resolution?

A. Focal spot size | B. mAs | C. kVp | D. Filtration /// Answer: A

Which factor increases magnification?

A. Decreased OID | B. Increased SID | C. Decreased SID | D. Increased OID /// Answer: D

What is the smallest unit of magnetism?

A. Proton | B. Electron | C. Atom | D. Magnetic dipole /// Answer: D

Which factor primarily affects radiographic sharpness?

A. mAs | B. Focal spot size | C. kVp | D. Filtration /// Answer: B

Which term describes the amount of energy deposited per unit distance by ionizing radiation?

A. RBE | B. OER | C. Dose rate | D. LET /// Answer: D

Which type of radiation has high LET?

A. X-rays | B. Alpha particles | C. Gamma rays | D. Visible light /// Answer: B

Which radiation is generally considered low-LET radiation?

A. Alpha particles | B. X-rays | C. Neutrons | D. Heavy ions /// Answer: B

What is the primary purpose of quality assurance?

A. Ensure consistent and optimal imaging performance | B. Increase patient dose | C. Eliminate all maintenance | D. Increase equipment cost /// Answer: A

Quality control primarily involves:

A. Patient scheduling | B. Equipment purchasing | C. Monitoring equipment performance | D. Hospital billing /// Answer: C

Which test evaluates the accuracy of the x-ray tube voltage?

A. mAs reproducibility test | B. kVp accuracy test | C. Timer test | D. Linearity test /// Answer: B

Which test evaluates whether repeated exposures produce consistent results?

A. Focal spot test | B. Reproducibility test | C. Collimation test | D. Filtration test /// Answer: B

What is the purpose of an aluminum step wedge?

A. Measure SID | B. Test focal spot size | C. Evaluate image quality and exposure consistency | D. Measure patient thickness /// Answer: C

What does ALARA stand for?

A. As Low As Radiation Allows | B. As Low As Required Always | C. As Low As Reasonably Achievable | D. As Low As Radiography Allows /// Answer: C

Which is the most effective method of reducing radiation exposure to personnel?

A. Increasing mAs | B. Increasing distance | C. Increasing kVp | D. Increasing field size /// Answer: B

Which principle states that radiation intensity decreases with the square of the distance?

A. 15% rule | B. Line-focus principle | C. Inverse square law | D. Reciprocity law /// Answer: C

What is the primary source of occupational exposure to radiologic technologists?

A. Primary beam | B. Leakage radiation | C. Tube housing | D. Scattered radiation from the patient /// Answer: D

Which method provides protection from scattered radiation?

A. Increasing mAs | B. Using shielding | C. Increasing field size | D. Decreasing distance /// Answer: B

Which type of radiation protection device is worn by personnel?

A. Lead apron | B. Aluminum filter | C. Grid | D. Collimator /// Answer: A

What is the purpose of a lead apron?

A. Reduce radiation exposure | B. Increase image contrast | C. Increase radiation output | D. Reduce kVp /// Answer: A

What is the primary purpose of a radiographic grid?

A. Reduce scatter reaching the image receptor | B. Increase magnification | C. Increase focal spot size | D. Reduce SID /// Answer: A

What is the unit of absorbed radiation dose?

A. Gray | B. Sievert | C. Roentgen | D. Coulomb /// Answer: A

What is the SI unit of equivalent/effective dose?

A. Gray | B. Roentgen | C. Rad | D. Sievert /// Answer: D

Which quantity describes the energy deposited by radiation per unit mass?

A. Exposure | B. Activity | C. Absorbed dose | D. Half-life /// Answer: C

Which factor increases patient radiation dose?

A. Proper collimation | B. Increased mAs | C. Increased distance | D. Shielding /// Answer: B

What is the primary purpose of the x-ray generator?

A. Store images | B. Provide and control electrical power to the x-ray tube | C. Process images | D. Reduce patient motion /// Answer: B

Which component of the x-ray imaging system converts x-ray energy into a visible or electronic image?

A. Generator | B. Transformer | C. Collimator | D. Image receptor /// Answer: D