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