RAD 121 FINAL EXAM 2025/2026
QUESTIONS AND ANSWERS (GRADED
A)
Radiologic Quantities - ANSWER-dose, dose equivalent, exposure, and radioactivity
Derived quantities - ANSWER-velocity, acceleration, force, momentum, work, and
power
Fundamental quantities - ANSWER-mass, length, and time
Energy - ANSWER-is the ability to do work and has 2 states
potential - ANSWER-energy in a stored state (battery sitting on a shelf)
kinetic - ANSWER-energy being expended (battery is running a car)
electromagnetic radiation - ANSWER-is a way of ordering or grouping the different
electromagnetic radiations (is a form of energy that originates from the atom)
kVp aka - ANSWER-energy, penetrability, Qlty, Qty
mAs aka - ANSWER-intensity, qty, dose, # of photons
ALARA - ANSWER-As Low As Reasonably Achievable (responsibility to minimize
radiation dose to the patient, oneself, and others in accordance with ALARA Principle
Primary Barrier - ANSWER-1/16 inch have lead in the wall or the floor where the
primary beam is directed
Secondary Barrier - ANSWER-1/32 inch have lead in the wall, door, or any other area
that may receive scatter or leakage radiation
Atom - ANSWER-basic building block of matter composed of electrons, neutrons, &
protons
Electron - ANSWER-subatomic particle with 1 unit of negative electrical charge & mass
of 9.109 x10-31 kg
Grid Ratio - ANSWER-is defined as the ratio of the height of the lead strips to the
distance between them
, Spatial resolution - ANSWER-is used to evaluate accuracy of the anatomic structural
lines
pixel size - ANSWER-the greater the number, the better the S.R.
pixel pitch - ANSWER-the distance measured from the center of 1 pixel to the center of
the another
FOV - ANSWER-field of view is the area displayed on a monitor - the relationship
between FOV, pixel size, and matrix size is found as such:
Modulation Transfer Function (MTF) - ANSWER-a measure of the imaging systems
ability to display the contrast of anatomic objects varying in size
Spatial frequency - ANSWER-how images display variations in tissue (small objects
have a high spatial frequency, large objects have a lower spatial frequency. Measured
in line pairs per millimeter (lp/mm
Detective Quantum Efficiency (DQE) - ANSWER-a measure of the efficiency of an IR in
converting the exposure it receives to a quality image
Subject contrast - ANSWER-refers to absorption characteristics of anatomic tissue &
the quality of the beam
The anode - ANSWER-the positive end of the tube (provides the target for electron
interaction to produce x-rays)
stator - ANSWER-is made up of electromagnets arranged in pairs around the rotor. The
stator is outside the tube enclosure
rotor - ANSWER-is made of an iron core (iron bars embedded in the copper shaft)
surrounded by coils. The rotor is located in the center of the stator, but inside the
enclosure
Distortion - ANSWER-is the radiographic misrepresentation of size (magnification) or
shape (foreshortening/elongation) of the anatomic part. When the image is distorted,
spatial resolution is decreased
SID - source (of x-rays) to image (IR) distance - ANSWER-if the source is closer to the
IR, the part is magnified
OID - object (part) to image (IR) distance - ANSWER-parts that are further away from
the IR are magnified
Shape Distortion - ANSWER-this can occur from misalignment of the tube/part/IR
QUESTIONS AND ANSWERS (GRADED
A)
Radiologic Quantities - ANSWER-dose, dose equivalent, exposure, and radioactivity
Derived quantities - ANSWER-velocity, acceleration, force, momentum, work, and
power
Fundamental quantities - ANSWER-mass, length, and time
Energy - ANSWER-is the ability to do work and has 2 states
potential - ANSWER-energy in a stored state (battery sitting on a shelf)
kinetic - ANSWER-energy being expended (battery is running a car)
electromagnetic radiation - ANSWER-is a way of ordering or grouping the different
electromagnetic radiations (is a form of energy that originates from the atom)
kVp aka - ANSWER-energy, penetrability, Qlty, Qty
mAs aka - ANSWER-intensity, qty, dose, # of photons
ALARA - ANSWER-As Low As Reasonably Achievable (responsibility to minimize
radiation dose to the patient, oneself, and others in accordance with ALARA Principle
Primary Barrier - ANSWER-1/16 inch have lead in the wall or the floor where the
primary beam is directed
Secondary Barrier - ANSWER-1/32 inch have lead in the wall, door, or any other area
that may receive scatter or leakage radiation
Atom - ANSWER-basic building block of matter composed of electrons, neutrons, &
protons
Electron - ANSWER-subatomic particle with 1 unit of negative electrical charge & mass
of 9.109 x10-31 kg
Grid Ratio - ANSWER-is defined as the ratio of the height of the lead strips to the
distance between them
, Spatial resolution - ANSWER-is used to evaluate accuracy of the anatomic structural
lines
pixel size - ANSWER-the greater the number, the better the S.R.
pixel pitch - ANSWER-the distance measured from the center of 1 pixel to the center of
the another
FOV - ANSWER-field of view is the area displayed on a monitor - the relationship
between FOV, pixel size, and matrix size is found as such:
Modulation Transfer Function (MTF) - ANSWER-a measure of the imaging systems
ability to display the contrast of anatomic objects varying in size
Spatial frequency - ANSWER-how images display variations in tissue (small objects
have a high spatial frequency, large objects have a lower spatial frequency. Measured
in line pairs per millimeter (lp/mm
Detective Quantum Efficiency (DQE) - ANSWER-a measure of the efficiency of an IR in
converting the exposure it receives to a quality image
Subject contrast - ANSWER-refers to absorption characteristics of anatomic tissue &
the quality of the beam
The anode - ANSWER-the positive end of the tube (provides the target for electron
interaction to produce x-rays)
stator - ANSWER-is made up of electromagnets arranged in pairs around the rotor. The
stator is outside the tube enclosure
rotor - ANSWER-is made of an iron core (iron bars embedded in the copper shaft)
surrounded by coils. The rotor is located in the center of the stator, but inside the
enclosure
Distortion - ANSWER-is the radiographic misrepresentation of size (magnification) or
shape (foreshortening/elongation) of the anatomic part. When the image is distorted,
spatial resolution is decreased
SID - source (of x-rays) to image (IR) distance - ANSWER-if the source is closer to the
IR, the part is magnified
OID - object (part) to image (IR) distance - ANSWER-parts that are further away from
the IR are magnified
Shape Distortion - ANSWER-this can occur from misalignment of the tube/part/IR
