RADIOLOGY PHYSICS 2026/2027 QUESTIONS AND
SOLUTIONS RATED A+
✔✔Which waveform is represented by <1% ripple? - ✔✔high frequency
✔✔What is the purpose of the oil in the protective housing surrounding the x-ray tube? -
✔✔electrical insulator
thermal cushion
✔✔What is the term for x-rays that escape through the protective tube housing? -
✔✔leakage radiation
✔✔What are the purposes of the protective tube housing? - ✔✔reduces the level of
leakage radiation
protects against electric shock
provides mechanical support for the tube
protects the tube from damage
✔✔What are the 2 electrodes contained within the evacuated glass envelope? -
✔✔cathode (filament) and anode (target)
✔✔What is the purpose of the vacuum in the glass envelope? - ✔✔allows for more
efficient x-ray production
extends tube life
✔✔What is the term that describes the boiling of electrons from the filament? -
✔✔thermionic emission
✔✔What element is the target made of? - ✔✔tungsten
✔✔What element is the filament made of? - ✔✔tungsten
✔✔What is added to the filament to prevent vaporization? - ✔✔thorium
✔✔What is added to the target to strengthen it? - ✔✔rhenium
✔✔Why is tungsten the material of choice for targets? - ✔✔atomic number- high
efficiency and high energy
thermal conductivity- dissipates heat
high melting point- stand up to high tube current without pitting or bubbling
✔✔What are the 3 functions of the anode? - ✔✔electrical conductor
mechanical support
thermal conductor
, ✔✔What is the charge of the focusing cup? - ✔✔negative
✔✔What is the purpose of the focusing cup? - ✔✔to focus and accelerate the electrons
to the anode
✔✔Dual focus tubes allow for what? - ✔✔small and large focal spot sizes
✔✔How many revolutions per minute do most anodes rotate? - ✔✔3400 RPM
✔✔What are 2 benefits of the rotating anode? - ✔✔higher tube currents
shorter exposure times are possible
✔✔What mechanism spins the anode? - ✔✔rotor
✔✔Define effective focal spot - ✔✔focal spot projected onto the patient and image
receptor
✔✔Define actual focal spot - ✔✔area of target being hit with electrons
actual source of radiation
✔✔The heel effect causes which side of the x-ray beam to be more intense? -
✔✔cathode
✔✔What is the formula for calculating heat units? - ✔✔H.U. = kVp x mAs x C
single phase c = 1
three phase 6 pulse c = 1.35
three phase 12 pulse c = 1.41
✔✔What percentage of the kinetic energy of projectile electrons is converted to heat? -
✔✔99%
✔✔A projectile electron interacts with an inner shell electron of the target atom, what is
produced? - ✔✔characteristic x-rays
✔✔A projectile electron interacts with the target nucleus, what is produced? -
✔✔bremsstrahlung x-rays
✔✔Describe the 15% Rule - ✔✔an increase in 15% of kVp will be equivalent to
doubling mAs, vice versa (double density)
✔✔As this factor increases, beam quality increases, but the quantity of photons
decreases - ✔✔filtration
SOLUTIONS RATED A+
✔✔Which waveform is represented by <1% ripple? - ✔✔high frequency
✔✔What is the purpose of the oil in the protective housing surrounding the x-ray tube? -
✔✔electrical insulator
thermal cushion
✔✔What is the term for x-rays that escape through the protective tube housing? -
✔✔leakage radiation
✔✔What are the purposes of the protective tube housing? - ✔✔reduces the level of
leakage radiation
protects against electric shock
provides mechanical support for the tube
protects the tube from damage
✔✔What are the 2 electrodes contained within the evacuated glass envelope? -
✔✔cathode (filament) and anode (target)
✔✔What is the purpose of the vacuum in the glass envelope? - ✔✔allows for more
efficient x-ray production
extends tube life
✔✔What is the term that describes the boiling of electrons from the filament? -
✔✔thermionic emission
✔✔What element is the target made of? - ✔✔tungsten
✔✔What element is the filament made of? - ✔✔tungsten
✔✔What is added to the filament to prevent vaporization? - ✔✔thorium
✔✔What is added to the target to strengthen it? - ✔✔rhenium
✔✔Why is tungsten the material of choice for targets? - ✔✔atomic number- high
efficiency and high energy
thermal conductivity- dissipates heat
high melting point- stand up to high tube current without pitting or bubbling
✔✔What are the 3 functions of the anode? - ✔✔electrical conductor
mechanical support
thermal conductor
, ✔✔What is the charge of the focusing cup? - ✔✔negative
✔✔What is the purpose of the focusing cup? - ✔✔to focus and accelerate the electrons
to the anode
✔✔Dual focus tubes allow for what? - ✔✔small and large focal spot sizes
✔✔How many revolutions per minute do most anodes rotate? - ✔✔3400 RPM
✔✔What are 2 benefits of the rotating anode? - ✔✔higher tube currents
shorter exposure times are possible
✔✔What mechanism spins the anode? - ✔✔rotor
✔✔Define effective focal spot - ✔✔focal spot projected onto the patient and image
receptor
✔✔Define actual focal spot - ✔✔area of target being hit with electrons
actual source of radiation
✔✔The heel effect causes which side of the x-ray beam to be more intense? -
✔✔cathode
✔✔What is the formula for calculating heat units? - ✔✔H.U. = kVp x mAs x C
single phase c = 1
three phase 6 pulse c = 1.35
three phase 12 pulse c = 1.41
✔✔What percentage of the kinetic energy of projectile electrons is converted to heat? -
✔✔99%
✔✔A projectile electron interacts with an inner shell electron of the target atom, what is
produced? - ✔✔characteristic x-rays
✔✔A projectile electron interacts with the target nucleus, what is produced? -
✔✔bremsstrahlung x-rays
✔✔Describe the 15% Rule - ✔✔an increase in 15% of kVp will be equivalent to
doubling mAs, vice versa (double density)
✔✔As this factor increases, beam quality increases, but the quantity of photons
decreases - ✔✔filtration
