RAD 111 Exam question bank (exams 1 - 8)
Flux gain formula
# of output photons / # of input photons
% magnification formula
(image size - object size)/object size x 100
Watt
SI unit of power
How do you get SOD?
SID - OID = SOD
Contrast improvement factor
contrast obtained with a grid compared to contrast without a grid
What is the impact of increased beam restriction on the photographic properties of a radiographic image?
decreased density and higher contrast
If the distance between two electrical charges is doubled, the force between them is...?
decreased to one-fourth of the original
Brightness gain formula
minification gain x flux gain = brightness gain
What are some examples of involuntary motion?
peristalsis, the heartbeat, spasms, and tremors
Raster
refers to the raster pattern produced on the screen of a television picture tube by the movement of an electron beam or on film by a laser scan
Exposure indicator number
represents the amount of exposure to the image receptor
Where does the step-down transformer apply current to?
the filament
Ampere
unit of electric current
How to calculate lp/mm
(1/pixel pitch)/2
How much large should an anatomical part be for a radiographic grid to be used?
10 cm
According to NCRP guidelines, leakage radiation should not exceed...?
100 mR/hr at 1 meter
What is the approximate atomic number of bone?
14
Bit depth formula
2^(bit depth) = number of shades of grey produced
What is the speed of light?
3.00 x 10^8 m/s or 186,000 miles per second
What is the approximate atomic number of fat?
6.3
What is the approximate atomic number of muscle?
7
What is the primary x-ray beam made of?
85% Bremsstrahlung radiation, 15% characteristic radiation
15% kVp rule
A 15% increase in kVp has the same effect as doubling the mAs. A 15% decrease in kVp has the same effect as decreasing the mAs by half.
Capacitor
A basic electrical component that stores electric charge. They are made from two electrical conductors separated by an insulator.
What minimizes magnification?
A long SID and short OID
Attenuation
A loss of some of the energy from the x-ray beam as it passes through the tissue being imaged. Absorption + scatter = attenuation
Permanent magnet
A magnet that retains its magnetism after it is removed from a magnetic field. A permanent magnet is always on.
Superconductor
A material whose electrical resistance drops to zero when its temperature is lowered beyond a certain critical temperature. Superconductors consist of special metal alloys that include niobium and titanium.
Optical density (OD)
A measure of the degree of darkness or blackening on a radiograph. It is the logarithm of the ratio of the light intensity incident on the film to the light intensity transmitted through the film.
Photon
A small, discrete bundle of pure energy. X and gamma radiation, which are at the high-energy level of the electromagnetic spectrum, act more like particles and are described as photons.
Rotating anodes are manufactured to rotate at a range of speed between... A.) 3,000 to 10,000 revolutions per minute (RPM) B.) 5 to 50 revolutions per minute (RPM) C.) 80 to 100 revolutions per minute (RPM) D.) 1,000 to 5,000 revolutions per minute (RPM)
A.) 3,000 to 10,000 revolutions per minute (RPM)
What is the smallest percentage of increase in milliamperage-seconds that will produce a noticeable change in radiographic density? A.) 30% B.) 50% C.) 10% D.) 75%
A.) 30%
The primary function of filters in an x-ray tube is to... A.) absorb low-energy x-ray photons B.) restrict the field size of the primary beam C.) enhance radiographic contrast D.) prevent scattered radiation from reaching the image receptor
A.) absorb low-energy x-ray photons
The area in the x-ray tube under bombardment by electrons is the... A.) actual focal spot B.) effective focal spot C.) large focal spot D.) dual focal spot
A.) actual focal spot
What type of electrical current is necessary for a transformer to function? A.) alternating current B.) pulsating direct current C.) direct current D.) constant potential
A.) alternating current
The filter in a general diagnostic x-ray unit is usually made of... A.) aluminum B.) silver C.) molybdenum D.) rhenium
A.) aluminum
The most common material used for the input phosphor of the image intensifier is... A.) cesium iodide B.) lanthanum oxybromide C.) calcium tungstate D.) zinc cadmium sulfide
A.) cesium iodide Cesium iodide absorbs remnant (exit) radiation and emits light in response
The cascading effect that occurs from electrons of an outer shell filling a vacancy in an inner shell that occurs in target atoms and generates X-ray photon emission occurs during the... A.) characteristic interaction B.) Compton interaction C.) bremsstrahlung interaction D.) photoelectric interaction
A.) characteristic interaction
Which of the following is classified as a ferromagnetic material? A.) cobalt B.) glass C.) copper D.) aluminum
A.) cobalt
When using the automatic exposure control (AEC), what should the radiographer adjust to manipulate the overall blackening of the film image or signal intensity to the image receptor? A.) density controls B.) back-up time C.) kVp D.) focal spot size
A.) density controls
What is the location on a histogram graph of background brightness? A.) far right B.) center C.) far left D.) lower half
A.) far right
Which of the following characteristics of tungsten increases x-ray production? A.) high atomic number B.) durability C.) high thermal conductivity D.) low melting point
A.) high atomic number
Which type of x-ray generator has the least amount of voltage ripple? A.) high-frequency x-ray unit B.) three-phase, 12-pulse x-ray unit C.) single-phase, half-wave rectified x-ray unit D.) single-phase, full-wave rectified x-ray unit
A.) high-frequency x-ray unit
Which of the following changes would correct an underexposed image that was adequately penetrated? A.) increase mAs B.) decrease exposure time C.) decrease kVp D.) increase SID
A.) increase mAs
How does tube filtration affect the energy of the useful x-ray beam? A.) increases the average energy of the beam B.) reduces the energy by one-fourth C.) filtration does not affect the energy of the beam D.) reduces the beam energy by half
A.) increases the average energy of the beam Removing low-energy photons produces a higher quality beam, thus increasing the average energy of the beam
Coherent scattering occurs only when incident photon energy... A.) is lower than 10 keV B.) exceeds 1.02 MeV C.) ranges from 70 to 120 keV D.) ranges from 50 to 69 keV
A.) is lower than 10 keV
The energy of the x-ray photons are best controlled by... A.) kVp B.) mA C.) SID D.) exposure time
A.) kVp
Which of the following will NOT make the anode-heel effect less noticeable? A.) long exposure time B.) larger anode angle C.) smaller field size D.) longer SID
A.) long exposure time
In order to produce a just perceptible increase in radiographic density, the radiographer must increase the A.) mAs by 30 percent B.) mAs by 15 percent C.) kVp by 15 percent D.) kVp by 30 percent
A.) mAs by 30 percent
Magnetism is caused by... A.) moving electric charges B.) static photons C.) moving magnetic charges D.) static electric charges
A.) moving electric charges
The primary reason why an increase in kVp increases radiographic density is that an increase in kVp increases the... A.) penetrating power of the x-rays B.) amount of x-rays produced at the anode C.) absorption of x-ray photons D.) efficiency of the x-ray tube
A.) penetrating power of the x-rays
A device that has coils of current carrying wire wrapped around an iron core is called... A.) permanent magnet B.) electromagnet C.) commutator D.) solenoid
A.) permanent magnet
What is the device in the image reader that collects, amplifies, and converts the released light to an electronic signal? A.) photomultiplier tube B.) laser C.) cathode ray tube D.) electrostatic lenses
A.) photomultiplier tube
When there is an increase in the mAs during an exposure and no other technical changes are made, which of the following will increase? A.) radiographic density/signal to the image receptor B.) energy of the x-ray beam C.) subject contrast D.) recorded detail
A.) radiographic density/signal to the image receptor
What is the location on a histogram graph of air/gas? A.) right B.) left upper corner C.) center D.) left lower corner
A.) right
Which transformer design is the most efficient one? A.) shell core B.) open core C.) air core D.) closed core
A.) shell core The shell-type transformer is the most efficient design. In the shell type of transformer the core contains a center post with two rectangular holes on both side. Both the primary and secondary coils are wrapped around the center post of the core. In this way the ferromagnetic core completely surrounds the coils. This traps more of the magnetic field lines generated in the coils and makes the transformer more efficient.
When electrons accumulate near the x-ray tube filament wire, the condition is called the... A.) space charge effect B.) ionization effect C.) thermal effect D.) inverse square effect
A.) space charge effect
What is the name of the device in a rotating anode x-ray tube that turns the rotor? A.) stator B.) ball bearings C.) focusing cup D.) rheostat
A.) stator
The three rectangles (see red arrows) on the upright (vertical) Bucky device represent the location of the...?
AEC detectors
Conductor
Allows the free flow of electrons and has a low resistance. Examples of conductors are copper and silver.
Pixel
Also known as a picture element. It is the cell of a digital matrix image.
Exposure angle
Also known as the exposure arc or exposure amplitude. The distance of the x-ray tube moves during the exposure.
Radionuclide
An atom with an unstable nucleus. They may occur naturally, but can also be artificially produced. Radionuclides are also referred to as radioactive isotopes or radioisotopes.
Transformer
An electrical device that transfers energy between two or more circuits through electromagnetic induction. In the x-ray circuit, transformers are used to increase or decrease the voltages of alternating current.
Negative contrast media
Appears black on the x-ray. Example: air
Positive contrast media
Appears white on the x-ray. Examples: bone, barium, iodine
The fluoroscopic tabletop exposure rate should not exceed A.) 0.001 R/min. B.) 10 R/min. C.) 0.1 R/min. D.) 2 R/min.
B.) 10 R/min.
Three-phase power consists of three single-phase voltage waveforms separated by... A.) 90 degrees B.) 120 degrees C.) 180 degrees D.) 30 degrees
B.) 120 degrees
When the entering x-ray photon loses energy and changes its path of travel as a result of interacting with an atom, the interaction is known as the... A.) photoelectric interaction B.) Compton interaction C.) Coherent scattering D.) anode heel effect
B.) Compton interaction
Which of the following would offer the greatest resistance to the flow of electric current? A.) a long, thick wire B.) a long, thin wire C.) a short, thin wire D.) a short, thick wire
B.) a long, thin wire The amount of resistance of a particular conductor depends on four factors: material, conductor (low resistance), insulator (high resistance); length, long conductor (high resistance) or short conductor (low resistance); diameter, small diameter (high resistance) or large diameter (low resistance); temperature, high temperature (high resistance) and low temperature (low resistance). A long thin wire would result in the greatest resistance.
Which of the following radiations would be the least penetrating? A.) x-rays B.) alpha particles C.) gamma rays D.) beta particles
B.) alpha particles
During a Compton interaction with matter, the incident photon interacts with... A.) the nucleus of the atom B.) an outer shell electron C.) the force field of the nucleus D.) an inner shell electron
B.) an outer shell electron
Where are x-rays emitted from? A.) rotor B.) anode C.) cathode D.) filament
B.) anode
Which of the following phosphors are used in computed radiography imaging plates? A.) terbinum-doped gadolinium dioxide sulfide B.) barium fluorohalide bromides and iodides with europium activators C.) cesium iodide and amorphous silicon D.) barium lead sulfate
B.) barium fluorohalide bromides and iodides with europium activators
Which of the following changes are permitted by the autotransformer? A.) alternating current is converted to direct current B.) changes in kVp C.) volts is changed to kilovolts D.) changes in exposure time
B.) changes in kVp
Which of the following is a good conductor of electricity? A.) silicon B.) copper C.) glass D.) rubber
B.) copper
An electric current in a solid conductor consists of a flow of... A.) protons B.) electrons C.) neutrons D.) waves
B.) electrons
The function of the electrostatic lenses located along the length of an image intensifier tube is to focus the... A.) light to the output screen B.) electrons to the output phosphor screen C.) x-ray photons to the photocathode D.) electrons to the input phosphor screen
B.) electrons to the output phosphor screen
The traditional method (i.e., old!) for specifying the x-ray beam quality is the... A.) grid frequency B.) half-value layer C.) reciprocity law D.) resolution tool
B.) half-value layer
Most diagnostic x-ray tubes manufactured today have a rotating anode because they... A.) are more cost effective B.) have a greater thermal capacity C.) do not produce scattered radiation D.) require less tube filtration
B.) have a greater thermal capacity
The electromagnetic radiation at a frequency just below visible light, often called heat waves, is which of the following? A.) ultraviolet radiation B.) infrared radiation C.) cosmic radiation D.) microwave radiation
B.) infrared radiation
The beveled edge of a rotating anode indicates what? A.) it will not produce the anode heel effect B.) it's constructed according to the line focus principle C.) it has been damaged from excessive heat loads D.) it's a dual filament x-ray tube
B.) it's constructed according to the line focus principle The design of the angle of the target is based on the line-focus principle. By slanting (angling) the target there is a larger area for heat distribution and a smaller effective focal spot. Thus you have greater heat dissipation and a sharper image with an angled (belved) target.
Radiation traveling through the tube housing, not in the direction of the useful beam, is called what? A.) remnant radiation B.) leakage radiation C.) primary radiation D.) exit radiation
B.) leakage radiation
How is the spatial resolution of a digital image is measured? A.) bits per second (bps) B.) line pairs per millimeter (lp/mm) C.) candelas per meter squared (cd/m2) D.) log of median (LgM)
B.) line pairs per millimeter (lp/mm)
The principle that allows the primary side of the high-voltage transformer to generate voltage in the secondary side is called... A.) self-induction B.) mutual induction C.) Coulomb's law D.) inverse square law
B.) mutual induction
If a positively charged object comes in contact with an uncharged object, the uncharged object will have a... A.) cannot be determined B.) positive charge C.) neutral charge D.) negative charge
B.) positive charge
Which of the following groups of electromagnetic radiation is listed correctly in order of increasing frequency? A.) visible light, gamma rays, X-rays B.) radio waves, visible light, X-rays C.) x-rays, visible light, radio waves D.) ultraviolet radiation, visible light, X-rays
B.) radio waves, visible light, X-rays
Which element is applied to the anode target to prevent pitting? A.) molybdenum B.) rhenium C.) graphite D.) thorium
B.) rhenium
The best method for limiting involuntary motion during a radiographic procedure is to use a... A.) short OID B.) short exposure time C.) large focal spot size D.) restraining device
B.) short exposure time The use of a short exposure time and providing concise instructions to the patient are the primary methods used to control involuntary motion.
A device that can increase or decrease electrical voltage in the x-ray circuitry is a/an... A.) intensifier B.) transformer C.) amplifier D.) attenuator
B.) transformer
When are grids used? A.) when OID cannot be reduced B.) when the kVp is high C.) when the exposure time is long D.) when the area of interest is small E.) all of the above
B.) when the kVp is high
Which of the following types of electromagnetic radiation has the shortest wavelength? A.) radio waves B.) x-rays C.) visible light D.) infrared waves
B.) x-rays
_______ determines how many shades of grey can be displayed in an image
Bit depth
Which SNR is used in digital systems to produce an image with the least amount of noise? A.) 500:1 B.) 100:1 C.) 1,000:1 D.) 200:1
C.) 1,000:1 The larger the signal is to the noise, the less noisy that the image will be
Which matrix size would produce the highest spatial resolution? A.) 128 x 128 B.) 256 x 256 C.) 1,024 x 1,024 D.) 512 x 512
C.) 1,024 x 1,024 The greater the matrix size, the higher the spatial resolution
The minimum amount of energy that is required for a pair production interaction is to occur is A.) 102,000 eV B.) 69.5 keV C.) 1.02 MeV D.) 10 keV
C.) 1.02 MeV
What is an acceptable level of leakage from the tube housing? A.) 1000 R/hr measured at a distance of 4 meters B.) 100 mR/hr measured 6 feet away C.) 100 mR/hr measured at a distance of 1 meter D.) 10 mR/hr measured 1 foot away
C.) 100 mR/hr measured at a distance of 1 meter
In stationary fluoroscopy, what is the minimum distance needed between the x-ray tube and the tabletop? A.) 8 inches B.) 10 inches C.) 15 inches D.) 12 inches
C.) 15 inches
The interaction of the projectile electrons and the nuclear field of the target atom is referred to as... A.) extrafocal radiation B.) Compton scatter radiation C.) Bremsstrahlung radiation D.) characteristic radiation
C.) Bremsstrahlung radiation
Which of the following is a measure of the efficiency of an image receptor in converting the x-ray exposure it receives to a quality radiographic image? A.) TFT B.) SNR C.) DQE D.) DEL
C.) DQE
What type of monitor passes light through liquid crystals to display a digital image? A.) CRT B.) PACS C.) LCD D.) LUT
C.) LCD
What is the major controlling factor of magnification? A.) SID B.) SOD C.) OID D.) FSS
C.) OID
What is the function of a radiographic grid? A.) control the size of the x-ray beam B.) reduce patient dose C.) absorb scattered radiation and enhance contrast D.) immobilize the area of interest
C.) absorb scattered radiation and enhance contrast
The speed (velocity) of the electron stream across an x-ray tube is primary controlled by the... A.) vacuum condition of the x-ray tube B.) temperature of the filament wire C.) applied kilovoltage D.) applied filament current
C.) applied kilovoltage
What is the timer located between in an x-ray circuit? A.) secondary side of the step-down transformer and x-ray tube B.) mA selector and the primary side of the step-down transformer C.) autotransformer and the primary side of the step-up transformer D.) rectifiers and the x-ray tube
C.) autotransformer and the primary side of the step-up transformer
The energy that holds electrons at specific levels or shells with the atom is called... A.) kinetic energy B.) potential energy C.) binding energy D.) atomic energy
C.) binding energy
What happens/is produced during a photoelectric interaction? A.) a scattered photon that has a lower energy and a longer wavelength than the incident x-ray photon B.) partial absorption of the incident x-ray photon C.) complete absorption of the incident x-ray photon D.) a scattered photon that has a higher energy and a shorter wavelength than the incident x-ray photon
C.) complete absorption of the incident x-ray photon
In digital imaging field of view refers to the... A.) smallest part of an image that can be visualized B.) ratio of the width of a display screen to the height C.) dimensions of the anatomical area of interest D.) range of gray scale values displayed on a digital image
C.) dimensions of the anatomical area of interest
On which part of a conductor will an electric charge be found? A.) internal surface B.) throughout the conductor C.) external surface D.) central portion
C.) external surface According to the laws of electrostatics, electric charges reside on the external surface of a conductor.
In which equal volume of tissue does the least amount of absorption occur when the body is exposed to diagnostic x-rays? A.) muscle B.) liver C.) fat D.) bone
C.) fat
What does a dual-focused x-ray tube have two of? A.) filters B.) exit windows C.) filaments D.) anodes
C.) filaments
A filter placed in the path of an x-ray beam results in what? A.) a homogeneous beam B.) a reduction in the average beam energy C.) hardening of the x-ray beam D.) softening of the x-ray beam
C.) hardening of the x-ray beam The purpose of tube filtration is to remove low-energy (soft) x-ray photons from the beam before they strike the patient. Adding filtration selectively removes the soft (lower-energy) x-ray photons from the beam, which do not contribute any useful diagnostic information to the image, and reduces radiation dose to the patient. Beam filtration also hardens the x-ray beam.
The target material used for the anode of an x-ray tube must have a... A.) high atomic number and low melting point B.) low atomic number and low melting point C.) hight atomic number and high melting point D.) low atomic number and high melting point
C.) hight atomic number and high melting point
Where are the sensors located in an automatic exposure (AEC) device that converts x-ray photons into an electrical signal? A.) below the x-ray tube housing B.) inside the image receptor C.) immediately in front of the image receptor D.) in front of the patient
C.) immediately in front of the image receptor
The total quantity of x-ray photons produced during an exposure is directly controlled by... A.) kilovoltage peak B.) beam attenuation C.) milliampere-seconds D.) added tube filtration
C.) milliampere-seconds
A small, discrete bundle of energy is known as a... A.) phaser B.) quark C.) photon D.) mesion
C.) photon
Which particles have the same mass as one another? A.) neutrons and electrons B.) protons, neutrons, and electrons C.) protons and neutrons D.) electrons and protons
C.) protons and neutrons
Any material that greatly reduces the number of incident x-ray photons passing through the material is classified as... A.) radiotransparent B.) radiolucent C.) radiopaque D.) isotropic
C.) radiopaque
An electronic device that allows current to flow easily in only one direction is termed... A.) autotransformer B.) stator C.) rectifier D.) alternator
C.) rectifier
The major advantage of digital imaging systems over conventional film screen systems is A.) improved spatial resolution B.) less quantum mottle C.) wider dynamic range D.) lower patient dose
C.) wider dynamic range
Who was recognized as the first American X-ray martyr?
Clarence Dally
At a distance of 1 meter from the source of radiation the maximum amount of leakage radiation that is permissible when the tube is operated at maximum output is... A.) 50 mR/hr B.) 5 mR/hr C.) 25 mR/hr D.) 100 mR/hr
D.) 100 mR/hr
At high kVp levels (70 kVp or above), the most common x-ray interaction with matter is the... A.) coherent interaction B.) photoelectric interaction C.) transmission D.) Compton interaction
D.) Compton interaction
The anode heel effect will be most noticeable by using a... A.) short source-image receptor distance (SID) B.) steep target angle C.) large image receptor size D.) all of the above
D.) all of the above
What factors effect subject contrast? A.) kilovoltage B.) tissue density C.) thickness of anatomical part D.) all of the above
D.) all of the above
What properties below apply to diagnostic x-rays? A.) highly penetrating B.) polyenergetic C.) produce biological damage D.) all of the above
D.) all of the above
The total reduction in the number of x-ray photons in an x-ray beam following penetration through a given thickness of matter is termed... A.) absorption B.) filtration C.) transmission D.) attenuation
D.) attenuation
The quality of the characteristic radiation emitted from the x-ray tube at 110 kVp is determined by A.) amount of tube filtration B.) tube current C.) whether a three-phase or high frequency generator is used D.) composition of the target material
D.) composition of the target material
The most critical factor to consider when using the automatic exposure control (AEC) is... A.) using the appropriate SID B.) setting the correct mAs C.) setting the correct exposure time D.) correctly positioning the patient
D.) correctly positioning the patient
For a fixed field of view, increasing the matrix size will do what? A.) decrease pixel size and decrease spatial resolution B.) increase pixel size and increase spatial resolution C.) increase pixel size and decrease spatial resolution D.) decrease pixel size and increase spatial resolution
D.) decrease pixel size and increase spatial resolution
What effect does a large-diameter conductor have on resistance? A.) alternately increases and decreases B.) increases C.) it has no effect D.) decreases
D.) decreases
The range of exposure intensities an image receptor can accurately detect is referred to as... A.) field of view B.) spatial frequency C.) contrast resolution D.) dynamic range
D.) dynamic range
In the line-focus principle, the area projected onto the patient and the image receptor is the... A.) fractional focal spot B.) focal track C.) actual focal spot D.) effective focal spot
D.) effective focal spot
The amount of scattered radiation produced during a radiographic procedure is dependent on all of the following EXCEPT... A.) kVp level B.) thickness of tissue C.) beam restriction D.) focal spot size
D.) focal spot size
Which of the following is a correct description of the relationship between the wavelength and the frequency of the x-ray photon? A.) wavelength and frequency are directly proportional. B.) wavelength and frequency are inversely related by the square root of lambda. C.) wavelength and frequency have no relationship to each other. D.) frequency and wavelength are inversely related.
D.) frequency and wavelength are inversely related.
The undesirable absorption of the primary beam by the radiographic grid is called... A.) grid attenuation B.) grid air-gap C.) grid radius D.) grid cutoff
D.) grid cutoff
The filament circuit is used to do what? A.) terminate the exposure B.) increase the voltage applied to the x-ray tube C.) reduce the voltage ripple D.) heat the filament wire
D.) heat the filament wire
In the coherent interaction with matter the... A.) incident photon contains more energy than the scattered photon B.) scatter photon contains more energy that the incident photon C.) scattered photon is deflected 180 degrees from the incident photon D.) incident photon and the scatter photon have equal amounts of energy
D.) incident photon and scatter photon have equal amounts of energy
The removal of an orbital electron from an atom is termed... A.) intensification B.) scattering C.) absorption D.) ionization
D.) ionization
Which technical factor is routinely changed for each patient when using a fixed kVp technique chart? A.) grid ratio B.) source-image receptor distance C.) focal spot size D.) mAs
D.) mAs When using a fixed kVp chart, the kVp is kept the same for a particular body part, and the mAs is varied for patients of different sizes to produce the appropriate density on the radiograph. Measurement of the anatomical part is not required for the Fixed kVp/Variable mAs technique chart.
Which technical factor controls current? A.) kilovoltage peak B.) inherent tube filtration C.) rotor D.) milliamperage
D.) milliamperage
What is the main difference between x-rays and gamma rays? A.) velocity B.) charge C.) mass D.) origin
D.) origin
Which of the following x-ray interactions with matter is primarily responsible for radiographic contrast? A.) Compton interaction B.) photodisintegration C.) bremsstrahlung interaction D.) photoelectric interaction
D.) photoelectric interaction
Which of the following terms can be used interchangeably with the term EMF? A.) ampere and voltage B.) potential difference, ampere, and voltage C.) potential difference and ampere D.) potential difference and voltage
D.) potential difference and voltage
The difference between the shades of gray and black that make up the radiographic image is the... A.) optical density B.) exposure latitude C.) resolution D.) radiographic contrast
D.) radiographic contrast
When a radiographer changes from a small to a large focal spot for an exposure, what is he/she actually doing? A.) reducing the patient exposure B.) increasing the average energy of the beam C.) increasing the anode angle D.) selecting the larger filament wire
D.) selecting the larger filament wire
Which exposure indicator system is used by Fuji systems? A.) logarithm of the mean (LgM) B.) exposure index (EI) C.) target exposure index (EIT) D.) sensitivity (S)
D.) sensitivity (S)
Most of the energy transferred from the filament electrons to the anode target goes to the production of A.) characteristic and bremsstrahlung radiation B.) characteristic radiation C.) bremsstrahlung radiation D.) thermal energy
D.) thermal energy Remember: The kinetic energy of the high-speed filament electrons are converted into x-rays and heat at the anode target. Only 1% of the conversion of energy taking place at the anode target results in the production of x-rays; the other 99% results in thermal (heat) energy.
The photosensitive array used in a direct radiography flat panel detector, which converts x-rays into electrical charge is called a/an... A.) capacitor B.) film digitizer C.) imaging plate D.) thin-film transistor
D.) thin-film transistor
The loss of brightness around the periphery of the fluoroscopic image is termed...? A.) hysteresis B.) penumbra C.) quantum mottle D.) vignetting
D.) vignetting
The adjustment of the image contrast with a digital unit is accomplished by using what? A.) low pass filtering B.) edge enhancement C.) window level D.) window width
D.) window width
The induced voltage across a stationary conductor in a stationary magnetic field is... A.) increased B.) decreased C.) reversed in polarity D.) zero
D.) zero
Radiopaque
Describes a material that does not allow x-ray photons to transmit through it, due to x-ray absorption. These structures absorb x-ray photons and result in a decrease in radiographic density (whiteness or light gray) on the image.
Radiolucent/radiotransparent
Describes a material that easily allows x-ray photons to transmit through it with little or no x-ray absorption. They do not absorb x-ray photons and result in an increase in radiographic density on the image. Also refers to a material that permits the passage of x-rays.
Space charge effect
During the process of thermionic emission, electrons are boiled off the cathode filament wire and form an electron cloud in the area next to the filament wire, which is called the space charge. The space charge, which is composed of a collection of negatively charged electrons, remains next to the filament wire as long as the filament is being heated. Since two negatively charged electrons repel each other, the build up of the space charge begins to prevent more electrons from being boiled off the filament. This tendency of the space charge to not allow more electrons to be boiled off the filament is called the space charge effect.
Which of the following is the unit for electrical potential? A.) Ampere B.) Tesla C.) Coulomb D.) Watt E.) Volt
E.) Volt
Blur/unsharpness calculation
FSS x OID/SOD
True or False: the actual focal spot is smaller than the effective focal spot.
False. It is larger.
Heat unit formula
HU = kVp x mA x time x C.F. (rectification constants/correction factor)
Short-scale contrast
High-contrast image. A radiograph that exhibits black and white with few shades. Produced with low kilovoltage.
Inverse square law formula
I1/I2=(D2)^2/(D1)^2
Long-scale contrast
Low-contrast image. A radiographic image with many shades of gray. Produced with high kilovoltage.
Magnification factor formula
MF = SID/SOD
Ferromagnetic
Materials that are strongly attracted to a magnetic force. Examples include iron, nickel, and cobalt.
Paramagnetic
Materials that are weakly attracted to a magnet. Examples of paramagnetic materials include aluminum and platinum.
Insulator
Materials that resist the flow of electrons and have a high resistance. Examples are rubber, wood, plastic, and glass.
Bremsstrahlung radiation
Occurs when a projectile electron completely avoids the orbital electrons of the tungsten atom in the target and travels very close to its nucleus. The very strong electrostatic force of the nucleus causes the electron to suddenly slow down. As the electron slows down it loses energy.
Pixel size formula
Pixel size = FOV/matrix size
Characteristic radiation
Produced when a projectile electron interacts with the electron from the inner K-shell of the tungsten atom in the target. The electron must have enough energy to eject the K-shell electron from its orbit. When the K-shell electron is ejected from its orbit, an outer-shell electron drops into the vacant position. The energy difference between the outer-shell electron and the K-shell is emitted as a characteristic x-ray photon.
Velocity
Refers to speed. The velocity of electromagnetic radiation is the speed of light.
Tesla
SI unit for magnetic induction (flux density)
Coulomb
SI unit of electric charge
Compton scatter radiation
The Compton (incoherent or modified) scattering interaction occurs when the incident photon ejects a loosely bound outer-shell electron, resulting in only partial absorption of the incident photon. During this event an electron is ejected (Compton or recoil electron) and a lower-energy, scattered photon released.
Radiographic contrast
The difference between the shades of gray and black that make up the radiographic image. It can also be defined as the difference in adjacent radiographic densities.
Wavelength
The distance between two successive crests or troughs in the waveform. It is expressed in meters.
Line-focus principle
The effect of making the actual focal spot size appear smaller when viewed from the position of the film because of the angle of the target to the electron stream. Greater unsharpness on the cathode end.
Shape distortion
The misrepresentation of the true shape of a structure. Refers to elongation and foreshortening.
Grid frequency
The number of lead strips per inch (or per centimeter) in a grid. The greater the frequency, the thinner the lead strips and the greater likelihood of scatter passing through and reaching the image receptor.
Fulcrum
The pivot point about which the x-ray tube and image receptor move in opposite directions. It determines the object plane that will be in focus.
Focal track
The portion of the anode where the high-voltage electron stream will impact. When discussing a rotating anode, this describes the circular path that will be impacted by the electron beam.
Dynamic range
The range of exposure intensities an image receptor can accurately detect. Digital image receptors have a wide dynamic range, which means they can detect and display a greater range of x-ray intensities.
Atomic mass number
The total number of protons and neutrons, or nucleons, in the nucleus of an atom. It may be represented by the capital letter A.
Who invented the handheld fluoroscope?
Thomas Edison
True or False: Scattered radiation has longer wavelengths than primary radiation.
True. This is because the exiting photon has a lower energy and frequency than the original incident photon.
Anode heel effect
Uneven distribution of radiation intensity in the x-ray beam. Greater unsharpness on the anode end.
Ohm's Law
V = I x R
Transformer law formulas
Vs/Vp = Ns/Np (voltage and turns ratio) Ip/Is = Ns/Np (current and turns ratio) Ip/Is = Vs/Vp (current and voltage)
Solenoid
a coil of wire that produces a magnetic field when carrying an electric current
If an x-ray tube is not properly warmed up, a single large exposure could result in...?
a cracked anode
Ammeter
a device that measures the amperage (current) with an electrical circuit
Direct current
a flow of electric charge in only one direction
Alternating current
a flow of electric charge that regularly reverses its direction
Matrix
a group of numbers arranged in rows and columns
In the Compton effect, the incident photon loses energy by striking...
a loosely bound outer-shell electron and changing direction
An alpha particle has a mass number of ___ and an atomic number of ___.
a mass number of 4 and an atomic number of 2
Spatial frequency
a measure of spatial resolution and is usually expressed in line pairs per millimeter (lp/mm)
When a bar magnet is broken into two separate pieces, what will each piece have?
a north pole and a south pole
Dipole
a pair of separated electric charges or magnetic poles, of equal magnitude but of opposite sign or polarity
Autotransformer
a special single-coil transformer that corrects fluctuations in the current flowing through the x-ray machine
Commutator
a split ring used on direct current motors and electrical generators to convert alternating current to direct current
Rem
a tradition unit for effective dose and equivalent dose
Gauss
a unit of magnetic induction equal to one ten-thousandth of a Tesla
What type of photoconductor is used in direct flat panel radiography?
amorphous selenium
How are watts calculated?
amperes x volts
Resistor
an electrical component that limits or regulates the flow of electrical current in an electronic circuit
Negative ion
an electrically charged atom that is produced by adding electrons to a neutral atom
Positive ion
an electrically charged atom that is produced by removing electrons from a neutral atom
Diode
an electronic component that only allows current flow in one direction
What changes in OID and SID does the air-gap technique require?
an increase in both OID and SID
What is used to erase information from the CR imaging plate?
an intense white light
Shape distortion will most likely be caused by what?
angulation of the central ray
Nucleon
another name for particles that make up an atom (protons and neutrons)
Quantization
assigning a numerical value to a brightness value
Isotope
atoms of the same element that have different numbers of neutrons
Octet rule
atoms react by gaining or losing electrons so as to acquire the stable electron structure of a noble gas, usually eight valence electrons
Where does a prereading kVp voltmeter measure voltage?
between the autotransformer and the primary side of the step-up transformer
Where are rectifiers found in the x-ray circuit?
between the high-voltage transformer and the x-ray tube
What are some examples of voluntary motion?
blinking, swallowing, scratching, and talking
What type of photoconductor is used in indirect flat panel radiography?
cesium iodide
Rectifier
changes AC to DC
What type of radiation is produced following a photoelectric interaction?
characteristic radiation
Photomultiplier tube (PMT)
collects, amplifies, and converts the released light from the photostimulated phosphors in the imaging plate
Window level
controls brightness
Window width
controls contrast
Analog-to-digital converter (ADC)
converts analog signal to digital numbers
Motor
converts electrical energy into mechanical energy
Generator
converts mechanical energy into electrical energy
Law of Reciprocity
different combinations of mA and exposure time that produce the same mAs will produce the same density
Is mAs and grid factor (Bucky factor) directly or inversely proportional?
directly proportional
Is the relationship between photoelectric interaction and atomic number directly proportional or inversely proportional?
directly proportional
The process by which the rotor is turned is called _____.
electromagnetic induction
Gamma rays
electromagnetic radiation emitted from atomic nuclei
Hysteresis loss
energy loss due to the realignment of magnetic domains
Cathode ray tube
evacuated glass tube in which a stream of electrons emitted by a cathode strikes a fluorescent material, causing it to glow
True or False: An autotransformer operates on the principle of mutual induction.
false; it operates on self induction
The milliamperage is a measure of the...
flow of electrons from cathode to anode
The portion of the cathode responsible for keeping the stream of electrons between the cathode and anode as small as possible is called the _____.
focusing cup
What is the purpose of radiographic contrast?
gives visibility of detail to a radiographic image
What is the best way to decrease voluntary motion?
good communication skills
Grid ratio formula
h/D
Eddy currents
heat loss due to induced swirling currents in the iron core caused by the changing magnetic field
Copper (I2R) loss
heat loss due to resistance in coils
How ionizing are alpha particles?
heavily ionizing
What set of technical factors produces the greatest radiographic density?
highest mAs and lowest SID
Field of view
how much of the patient is imaged in a matrix
Isotropic
identical; in all directions
Elongation
images of objects that appear longer than the true objects
Foreshortening
images of objects that appear shorter than the true objects
Increasing kVp without making any other change to exposure factors will do what?
increase radiographic density and decrease radiographic contrast
What does a thicker body part result in?
increased attenuation and decreased contrast?
What is the principal disadvantage of conventional linear tomography?
increased patient dose
Atomic mass unit (amu)
indicates the mass of atoms, molecules, or nuclear particles
Stator
induction-motor electromagnets that turn the anode
Magnification calculation for fluoroscopy
input screen diameter/input during magnification
Minification gain formula
input screen diameter^2/output screen diameter^2
Is the relationship between voltage and current directly proportional or inversely proportional?
inversely proportional
What is the core material for a transformer made of?
iron
What is the purpose of the AEC?
it controls the exposure time
As beam restriction increases, does radiographic density increase or decrease?
it decreases
What is the principle advantage of conventional linear tomography?
it has better spatial resolution
What does the induction motor do?
it turns the rotor
An x-ray emission spectrum graph shows the number of photons on the vertical axis and horizontal axis illustrates e photon energy in units of ____.
keV
Electrostatic lenses
keep electron beam narrowed as it travels toward output phosphor
One of the advantages of using a high kVp technique is to increase _____.
latitude
Half-life
length of time required for half of the radioactive atoms in a sample to decay
What conversion occurs at the photocathode?
light --> electrons
What factors will create the greatest recorded detail?
long SID and small FSS
What combination of exposure settings and technical factors will produce a radiograph with the highest radiographic contrast?
low kVp and high grid ratio
What set of technical factors would produce the shortest scale of contrast?
lowest kVp and highest ratio grid
Place the following four tissue types in order from most radiolucent to most radiopaque: fat, lung, muscle, bone
lung, fat, muscle, bone
mAs formula
mAs = mA x time (seconds)
Density maintenance formula
mAs1/mAs2 = (D1)^2/(D2)^2
Screen formula
mAs2 = RSV1/RSV2 x mAs1
mAs1/mAs2 = grid conversion1/grid conversion2
mAs2 = mAs1 x gridconversion2/gridconversion1
DQE (detective quantum efficiency)
measurement of how efficient a system converts an x-ray input signal into a useful output image
Sensitometry
measures the response of film to exposure and processing
SOD for mobile fluoroscopy units
no less than 12 inches (30 cm)
SOD for fluoroscopy
no less than 15 inches (38 cm)
SOD for specific surgical fluoroscopy applications
no less than 8 inches (20 cm)
Backscatter radiation
photons that deflect back toward the source (180 degree angle), traveling in the opposite direction of the incident photon
Extrafocal radiation
photons that were not produced at the focal spot; also called off-focus radiation
Changing kVp changes the ____________________ of the Bremsstrahlung radiation produced and the _______________ of the Characteristic radiation produced by the x-ray tube.
quality and quantity/quantity
What will excessive scatter radiation produce?
radiation fog
Primary radiation
radiation that exits from the tube port
Leakage radiation
radiation that penetrates the lead-lined tube housing and is not part of the useful primary beam
Grid selectivity
ratio of transmitted primary radiation to transmitted scatter radiation
The laser color used to read out photostimulable phosphors is most commonly what color?
red
Quantity
refers to the number of x-rays produced in the x-ray unit
Quality
refers to the penetrating power of an x-ray beam
Voltage ripple
refers to the percentage drop from maximum voltage each pulse of current experiences
What factors will produce the greatest amount of magnification?
short SID and long OID
What factors will produce the greatest amount of unsharpness or blur?
short SID, long OID, large FSS
Percent ripples for generators
single phase, half-wave: 100% single phase, full-wave: 100% three phase, six pulse: 13.5% three phase, twelve pulse: 3.5% high frequency: 1%
Heat units for generators
single-phase units: 1 three-phase, 6-pulse units: 1.35 three-phase, 12-pulse units: 1.41 high frequency units: 1.45
What electron shell has the lowest binding energy?
the Q shell
Resolution
the ability of an imaging system to distinguish between closely spaced structures
Contrast resolution
the ability of the image receptor to distinguish between objects having similar subject contrast
Half-value layer (HVL)
the amount of absorbing material that will reduce the intensity of the primary beam to one-half its original value
Effective focal spot
the area of the focal spot that is projected out of the tube toward the object being radiographed
Actual focal spot
the area on the target surface that is struck by the electron stream
DICOM
the communication standard for information sharing between PACS and imaging modalities
OID
the distance between the patient and the image receptor
SID
the distance between the source (x-ray tube) and the image receptor
SOD
the distance between the source (x-ray tube) and the patient
What does it mean when a radiograph is overpenetrated?
the kVp is too high
Vignetting
the loss of brightness at the periphery (edges) of a fluoroscopic image
Frequency
the number of complete wavelengths that pass a point in a given time
Atomic number
the number of protons in an atom
What happens to the incoming photon in a photoelectric interaction?
the photon is completely absorbed
Exposure latitude
the range of acceptable exposures factors that will produce a diagnostic radiograph
Bucky factor
the ratio of the incident radiation striking the face of a grid to the transmitted radiation
Thermionic emission
the release of electron from a heated filament
Ionization
the removal of an orbital electron from an atom
Signal-to-noise ratio (SNR)
the signal-to-noise ratio (SNR) is a measure of the signal strength (useful information) and the background noise
What does the size of the effective focal spot depend on?
the target angle
Tomographic angle
the total distance the x-ray tube travels during conventional linear tomography
Volt
the unit of potential difference
Domains
the units that can align to form a magnet
Grid cutoff
the unwanted absorption of the primary beam by the grid
What do barium and iodine do to the x-ray beam?
they increase attenuation
Voxel
three-dimensional pixel; volume element
True or False: OID and recorded detail have an inversely proportional relationship.
true
True or false: No amount of mAs will make up for an insufficient amount of kVp.
true
Characteristic x-rays, which are useful in general diagnostic imaging, are produced from a ____ target and the ejection of a ___-shell electron.
tungsten, K
Hertz (Hz)
unit of measurement for frequency
Thin-film transistor (TFT)
used in direct flat panel radiography and turn x-rays --> electrical charge
Secondary radiation
x-radiation that is created when the primary beam interacts with matter
What conversion occurs at the input phosphor of an image intensification tube?
x-rays --> light
Exit (remnant) radiation
x-rays that exit the patient's body and strike the image receptor
Formula for calculating max number of electrons in a shell
2(n)^2
Step-down transformer
A transformer that decreases voltage and increases current. It has a greater # of primary windings than secondary windings.
The filament current in the x-ray circuit ranges from... A.) 3 to 5 A B.) 100 to 200 mA C.) 300 mA to 500 mA D.) 5 to 15 A
A.) 3 to 5 A
One of the major problems with automatic exposure control (AEC) is that... A.) positioning of the part is critical B.) minimal response time often interferes with the exposure C.) long exposure times cannot be used D.) backup timer often interferes with the exposure
A.) positioning of the part is critical
When a radiographic image appears to be elongated, the radiographer should... A.) readjust the x-ray tube, part, and image receptor alignment B.) decrease the OID C.) increase the mAs D.) increase the SID
A.) readjust the x-ray tube, part, and image receptor alignment
What will increasing the focal spot size do? A.) reduce the sharpness of the image B.) increase radiographic density C.) decrease magnification D.) all of the above
A.) reduce the sharpness of the image Increasing focal spot size will decrease the sharpness of the image because of the increase in the amount of penumbra (unsharpness) around the image
Which of the following factors will increase recorded detail? A.) smaller focal spot size B.) shorter SID C.) increased tube filtration D.) longer OID
A.) smaller focal spot size A shorter OID would also increase recorded detail!
In an AC induction motor, what is the name of the moving part? A.) stator B.) rotor C.) resistor D.) transformer
B.) rotor
What x-ray interaction causes film/image fog?
Compton scattering
Recorded detail on a radiograph will improve by decreasing which of the following factors? A.) SID B.) SOD C.) kVp D.) OID
D.) OID