Physics
The _______ is the SI unit equivalent to the Curie which measures radioactivity
Becquerel
Part of a DR system with indirect capture, the light-sensitive device that is commonly found in digital cameras is the
CCD
Which of the following digital detectors continues to improve and can be used in mammography and dental radiography?
CMOS
The negative electrodes of the x-ray tube in on the
Cathode
Given the anatomic part is adequately penetrated, changing the kVp will affect:
Compton scattering and subject contrast Previous
Which of the following imaging systems uses a cassette, a photostimulable phosphor plate, a plate reader, and a computer workstation?
Computed Radiography
The value that indicates exposure to the IR with a DR imaging system is the
DAP
A device that would be found on a direct exposure system as an exposure indicator is a:
DAP meter
which term indicated the flow of current in one direction
DC
The portion of the detector that receives the analog information is:
DEL
__________ is the standard format for digital medical images
DICOM
which is the most radiosensitive molecule in the body
DNA
Which of the following contributes to the radiographic or subject contrast present on a radiograph?
Degree of muscle developement Any pathologic processes Atomic number (Z#) of tissues radiographed
If the number of pixels is increased in a matrix, image ______ will be increased
Detail
What type of relationship does mAs have with the quantity of x-rays produced?
Direct proportional
Spatial resolution is the ability to
Distinguish between two objects as separate
which formula represents Planck's relationship between frequency and photon energy
E=hf
which formula represents planck's relationship between frequency and photon energy
E=hf
In CR, this represents the exposure level to the PSP plate
EI
Which of the following is an expression of the relative risk to humans of exposure to ionizing radiation
Effective Dose
Electromagnetic, chemical, electric, and thermal are all examples of which of the following
Energy
Which term refers to a phosphor's ability to emit visible light when stimulated by energy
Fluorescence
Which derived unit is the product of mass and acceleration of an object
Force
Which of the following statements is true concerning direct radiography (DR) systems?
Have detectors that directly capture and read out an electronic image signal.
Which type of body habitus is the thickest, requiring higher exposure factors?
Hypersthenic
Which of the following is the correct formula for the inverse square law?
I1/I2 = (D2)2/(D1)2
Which of the following is a cardinal rule of radiation protection
Increase the distance from the source
As the SID is increased, the mAs must be ___________ to maintain exposure to the image receptor (IR).
Increased
The property of an object to resist a change in motion is known as what
Inertia
What type of relationship does distance have with x-ray beam intensity?
Inverse proportional
The elements 73Li and 74Be demonstrate different atomic mass numbers. How are they characterized
Isobars
The primary factor influencing contrast with digital imaging is the
LUT
What type of response does digital imaging have to exposure
Linear
Which of the following is the formula to determine magnification factor?
MF = SID/SOD
The ideal expression of digital detector image resolution is the
MTF
In which condition is the electron binding energy stronger
Many protons, electrons close to the nucleus
On which day did Roentgen discover xradiation
November 8, 1895
The highest spatial frequency that a digital detector can record is the
Nyquist frequency.
The distance between the object being imaged and the image receptor is the
OID
What factor affects the amount of radiation intensity and scatter reaching the image receptor, magnification, and spatial resolution?
OID
To help dissipate the heat produced during xray production, what fills the xray tube housing
Oil
Where is the PSP plate located?
On the inside of the cassette
This type of storage involves data stored on hard drives with access times in milliseconds and transfer times in the range of tens and hundreds of megabytes per second
Online storage
In a typical radiographic room, where is the anode located
Over the head end of the table
__________ allows for the acquisition, display, and storage of digital images
PACS
When raw digital image data are corrected in the computer before viewing, it is known as:
Preprocessing
the electron binding energy would be the least in which orbital shell
Q
Exposure, dose, and dose equivalent are
Radiologic Quantities
With the photoelectric interaction, after the incident photon ejects an inner-shell electron, the energy of the photon is
Reduced to zero
The distance between the x-ray focal spot and the image receptor is the
SID
Which of the following is not a primary exposure technique factor?
SID
Which of the following will decrease size distortion (magnification) the most?
SID
The formula to determine the SOD (source to object distance) is
SOD = SID - OID.
The function of a thin-film transistor in an indirect DR system is to:
Serve as a switch that allows a capacitor to collect charge during exposure
The SI radiologic unit that addresses the different biological effects or different types of ionizing radiation is the
Sievert
The component of a flat panel detector that is responsible for absorbing electrons and generating the subsequent electrical charges to the image processor is the:
TFT
Which of the following is true concerning direct capture DR imaging?
The DR direct-capture method does not use a scintillator. The DR direct-capture method uses a photoconductor and TFT array. The DR direct-capture method avoids the loss of resolution caused by indirect-capture methods.
At higher kilovoltages within in the diagnostic range
The percentage of photoelectric interactions decreases
Rescaling a digital image adjusts the histogram to reflect which of the following?
VOI
Upright radiographic examinations can easily be done with which piece of equipment
Wall unit
Force x Distance is the formula to determine
Work
Put the following sequence of events in this indirect capture system in order1. The CCD converts the energy to an electronic signal2. The light energy is then transmitted to the CCD3. X-rays are absorbed by the scintillator and converted to light4. Electronic signal is sent to the computer work station for processing and display
X-rays are absorbed by the scintillator and converted to light, The CCD converts the energy to an electronic signal, The light energy is then transmitted to the CCD, Electronic signal is sent to the computer work station for processing and display.
Which of the following describes the extra step, and is therefore a limitation, of indirect-capture methods?
X-rays are converted to light and then to electrons.
Transmission refers to
X-rays leaving the patient that did not interact with atoms
The number of protons present in the atom determines which of the following
Z#
which of the curves have equal minimum wavelength and equal maximum energy
a and c
which of the following is needed to create an electromagnet
a coil of wire, an iron core, a solenoid
at 70 keV photon ionizes an outer shell electron. which of the following will result because of this interaction
a compton electron and a scatter photon
how does the x-ray emission spectrum change when switching from a high-frequency generator to a single-phase generator
a decrease along the x-axis a decrease along the y-axis
if all other factors remain constant, a decrease in mA results in which of the following changes to the x-ray emission spectrum
a decrease along the y-axis
If a different look-up table (LUT) or the volume of interest (VOI) is changed by the technologist:
a different tissue type would be accentuated
when a bremsstrahlung xray is produced
a projectile electron will lose energy
The charge coupled device (CCD) is?
a solid-state device that converts visible light photons to electrons
what does the anode function as
a target for electrons an electrical conductor a conductor for heat
attenuation of the x-ray beam in the diagnostic range is due to
absorption and scattering
what is the most likely cause of the change in the emission spectrum represented by the green line
added filtration
which of the following actions would serve to increase the average energy of or harden the xray beam
adding filtration
elements located in the same periodic table group share which of the following characteristics
all have the same number of electrons in the valence shell
to produce a radiographic image that represents anatomy, which interaction must be present
all of these (photoelectric interaction, transmitted photons, differential absoption)
Postprocessing functions
allow changes to be made in the appearance of the digital image. are done through computer software operations. include window width and window level adjustments.
radiographic contrast
allows visibility of anatomic structures
what type of material is used for filtration
aluminum
In Direct Digital Radiography, what is the substance that is both the capture element and the coupling element?
amorphous selenium
The complementary metal-oxide-semiconductor (CMOS) contains which of these components within it? Pick all that apply.
amplifier storage capacitor photodiode
when considering the wave properties of the electromagnetic radiation, what is the maximum height of a wave called
amplitude
what is a matrix
an array of cells arranged in rows and columns
what describes an ion pair
an atom and the electron that was removed from it
how is the x-ray emission spectrum changed with increasing kVp
an increase along the y-axis a shift to the right along the x-axis
which occurs during a photoelectric interaction
an inner-shell electron is ejected
what is potential energy
an object's stored energy
which of the following are taken into account when setting kVp and mAs
anatomic part, pathology, patient age
what is the relationship between kV and HVL
as KV increases, the HLV increases
what does ALARA mean
as low as reasonably achievable
in which instance does ionizing radiation intensity decrease
as the distance from the source of radiation increases
at what angle is compton scatter directed from the incident beam
at any angle
which term defines the reduction of an xray beam's intensity as it passes through matter
attenuation
which term describes the reduction of the xray beam's intensity as it passes through matter
attenuation
what device may be used to reduce repeats and ensure consistency of radiographic quality from one exposure to the next
automatic exposure control
in which portion of the xray circuit does self-induction occur
autotransformer
when the radiographer selects kilovoltage on the control panel, which device within the xray circuit is adjusted
autotransformer
which is the only adjustable transformer in the xray circuit
autotransformer
which part of the xray circuit functions by means of self induction
autotransformer
of the three spectra, which curve is most penetrating
b
The active layer in the photostimulable phosphor of a CR imaging plate is typically made of:
barium fluorohalide
The type of phosphor found in the PSP plate for computed radiography is:
barium fluorohalide
What is the photostimulable phospher used in CR imaging?
barium-fluoro-halide
for photoelectric interactions to occur, the energy of the incident photon may
be the same or greater than the binding energy of an inner-shell electron
in an automatic exposure control system (AEC), where are the detectors placed
between the patient and the image receptor
The number of visible shades of gray available per pixel in a digital image is determined by
bit depth
what is the purpose of the filament circuit
boil off electrons
what is the purpose of the filament in the xray unit
boil off electrons through thermionic emission
in which medium are photoelectric interactions most likely to occur
bone
the photoelectric interaction is most likely to occur in which tissue listed below
bone
what effects would be seen in the xray emission spectrum if a three-phase unit was used for the exposure rather than a single-phase machine
both the intensity and the average energy would increase
through what type of interaction are the majority of x-rays produced
brems
within diagnostic range, which type of interaction produces the majority of xray
brems
the majority of xray photons produced during an xray exposure are due to
brems interactions
which of the following is not one of the five basic xray interactions with matter
bremsstrahlung
tissues with higher atomic numbers appear ____ on a digital image
brighter
the amount of light emitted from the display monitor is
brightness
which device can temporarily store a charge
capacitator
The electrical device responsible for collecting charge in a circuit is the:
capacitor
due to heel effect, in which direction is radiation intensity leaving the tube the greatest
cathode
which is the negative end of the xray tue
cathode
Focal spot size is determined by
cathode filament size.
deposition of vaporized tungsten on the inner surface of the x-ray tube glass window
cause electron arcing
In indirect capture (indirect digital imaging), the scintillation device is commonly composed of:
cesium iodide
which of the following is correct regarding the display feature windowing
changing the window level will change the brightness level
what is the process of a series of outer-shell electrons filling inner-shell vacancies right after the other called
characteristic cascade
what type of xray photons are produced as a result of a characteristic cascade following a compton interaction
characteristic photons
what type of radiation occurs when an electron is ejected from an inner orbit of a target atom
characteristic radiation
which of the following is represented by a discreet emission spectrum
characteristic radiation
which of the following types of radiation cannot be produced at tube potentials of less than 70 kVp
characteristic radiation
which is a law of electrostatics
charges concentrate on curved surfaces
which interaction within the diagnostic range does not involve the removal of an orbital electron
classic scattering
in which interaction with matter does an xray interact with an atom without ionizing it
coherent scattering
Which of the following consists of lead filtration shutters
collimator
the x-ray interaction with anatomic tissue that is responsible for scattering is
compton
which of the following contributes most to image fog
compton
which of the following is a major source of occupational exposure
compton interactions
which photon/matter interaction increases the technologists dose and image fog
compton interactions
which process increases technologist dose and image fog
compton scattering
The part of a PSP plate that reduces and carries away static electricity is the
conductive layer
a material that freely allows the flow of electrons is known as
conductor
a material that freely allows the flow of electrons is known as what
conductor
if the number of pixels is increased in a matrix, image ____ will be increased
contrast
Visibility factors of a quality radiograph include
contrast and brightness
The ability of an imaging system to distinguish between small objects that attenuate the x-ray beam similarly defines
contrast resolution
which of the following helps to keep the xray tube cool on the inside of the protective housing
cooling fans and oil bath
which is the unit for electric charge (Si)
coulomb
what is an advantage of angling the anode
creates a smaller effective focal spot
which term describes the amount of electric charge flowing per second
current
if a lateral projection of an asthenic chest was performed using automatic exposure control (AEC) with an upper and outer photocells selected, what would be the likely outcome
decreased IR exposure
if the wavelength of a beam of electromagnetic radiation increases by a factor of 2, what happens to its frequency
decreased by 1/2
based on the anode heel effect, an image taken at 40 inches source-to-image receptor distance may demonstrate
decreased exposure toward the anode end of the beam
if a lateral projection of an asthenic chest was performed using AEC with the upper and outer photocells selected, what would be the likely outcome
decreased motion blur
which of these will decrease the digital image resolution
decreased pixel size
which characteristic of a conductor will create the least resistance to the flow of electrons
decreased temperature
as the wavelength of a wave increases, how will frequency change proportionately
decreases
When the distance is increased from 20 inches to 40 inches, the beam intensity
decreases by ¼.
Using a higher SID
decreases magnification
scatter radiaiton
decreases the visibility of anatomic structures.
Increasing the kVp has what affect on wavelength and frequency?
decreases wavelength and increases frequency.
As focal spot size decreases, unsharpness _________ and detail ___________.
decreases, increases
Patient radiation dose should be lower when utilizing a newer digital imaging system because of
defective quantum efficiency
In the direct radiography system. a charge-coupled device is used to:
detect and convert light photons to a digital signal
The values of interest (VOI)
determine what section of the histogram data set should be included in the displayed image.
which of the following contribute to subject contrast
differences in tissue thickness differences in tissue density effective atomic number ALL OF THE ABOVE
which of the following describes the process of radiographic image formation
differential absorption
which term describes how different body structures absorb xray photons to different extents
differential absorption
With digital imaging, overexposure of the IR and excessive dose to the patient can be
difficult to determine by looking at the image brightness and determined by checking the exposure indicator value.
What type of relationship does kVp have with exposure to the image receptor (IR)?
direct
Which of the following does not involve the conversion of x-rays to light rays?
direct capture DR system
which type of current is created by use of rectifiers
direct current
What type of relationship does mAs have with the exposure reaching the image receptor?
direct proportional
what purpose does the oil serve in the tube housing
dissipate heat
the inverse square law related intensity of electromagnetic radiation to which factor
distance
contrast resolution is the ability to
distinguish between small objects that attenuate the x-ray beam similarly
radiographic misrepresentation of the size or shape of the anatomic structure being imaged is:
distortion
how can you double the beam quantity
double the mAs
if kVp is decreased by 15%, what change in mAs should be made to maintain similar exposure on the IR
doubled
A 15% increase in kVp has the same effect as:
doubling the mAs
Increasing the kVp by 15% has the same effect as
doubling the mAs
The range of exposure intensities that an IR can respond to and acquire image data is
dynamic range
What is defined as "The range of exposure intensities an image receptor can accurately detect"
dynamic range
the range of exposure intensities an image receptor can accurately detect defines
dynamic range
which of the following is an expression of the relative risk to humans exposed to ionizing radiation
effective dose
what does the ampere measure
electric current
which is the study of electric charges in motion
electrodynamics
in the formula E=hf, how is energy measured
electron volts
What represents the latent image in a PSP CR system?
electrons trapped in the conduction band
which of the following occurs when frequency increases
energy increases
which of the following would most likely cause the anode to crack
excess heat applied to cold anode
how do low-energy xray photons act during coherent scattering
excite the atom, the photon changes direction as it exits the atom
What feature provides a numerical number value indicating the level of radiation exposure to the digital image receptor
exposure indicator
what important feature provides a numeric value indicating the level of radiation exposure to the digital image receptor
exposure indicator
The range of exposures that produce acceptable information to be used in image formation is
exposure latitude
which operating console choice selects large or small filamnet
exposure time, kVp, mA
which characteristic of a conductor will create the least resistance to the flow of electrons
extended length
A radiographic image that shows high subject contrast will have more shades of gray than an image with low subject contrast
false
Higher kVp results in less absorption and more variation in the intensities exiting the patient.
false
The greater the pixel bit depth the greater the number of shades of gray available for image display. Decreasing the bit depth will improve the contrast resolution of a digital image
false
after the x-ray beam enters the patient and has many photoelectric interactions, the quantity of the beam increases
false
because it reduced spatial resolution, it is always best to minimize shape distortion in radiographic imaging.
false
contrast resolution is the ability of the imaging system to represent 2 different structures with the same level of gray
false
decreasing the contrast-to-noise ratio will increase image quality
false
the probability of compton scattering depends on the atomic number
false
which describes a material that is strongly attracted to a magnetic field
ferromagnetic
where is the rheostat located
filament circuit
where is the step-down transformer located
filament circuit
which conditions and materials are necessary for mutual inducton to occur
fluctuating magnetic fields and a solenoid
dynamic imaging of internal structures can be visualized with a / an
fluorscopy
To release the latent image in computed radiography (CR), which of the following devices is scanned over the phosphor plate (IP)?
focused laser light
which component of the xray tube is responsible for concentrating the electron cloud
focusing cup
Unwanted scatter exposure to the image receptor will likely increase
fog
an artifact that is imaged within the patient's body is a
foreign body
rubbing a rubber rod with fur is an example of electrification through which method
friction
which direction is the normal flow of electrons
from a negative cathode to a positive anode
in which direction is the correct flow of electrons
from a negative cathode toward a positive anode
which of the following will four rectifiers produce
full-wave rectified current
what device coverts mechanical energy electrical energy
generator
Which of the following has an effect on how much mAs is used for a specific examination?
generator type. pathologic conditions present. a patient's age.
which unit of measure is used to quantify occupational exposure or dose equivalent
gray
The device used to absorb scatter radiation in the radiation leaving the patient before it reaches the image receptor is the
grid
Which of the following factors do not affect spatial resolution?
grid
The x-ray beam incident on the image receptor compared to the one incident on the patient
has less intensity
a radiographic image that has brightness levels that are very similar to each other
has low contrast and has long-scale contrast
the secondary photon that results from the photoelectric interaction
has low energy
which of the following are characteristics of xray
have no mass, pure energy, travel at a constant speed; diverge act like waves and bundles of energy; can harm living tissue, create ionizations in atoms; have an inverse proportionality between frequency and wavelength
a filament electron interacts with an outer-shell electron of tungsten but does not remove it. which of the following is produced
heat
of all the energy involved in xray production, 99% of it is converted to
heat
what does the formula kVp x mA x s x c calculate
heat units
what is thermonic emission
heating of the filament until electrons boil off
which unit is used to measure the frequency of a wave
hertz
which term characterizes the xray beam
heterogenous energy
To adjust the kVp to produce the desired contrast level, the kVp must first be
high enough to penetrate the part.
which has the least amount of ripple
high frequency generators
What is the relationship between kVp and subject contrast?
high kVp creates low subject contrast.
the target metals used in an xray tube must have which of the following properties
high melting point
what is the advantage of using a large focal spot
higher exposure may be used
what is the advantage of a rotating anode xray tube over a stationary xray tube
higher heat capacities
which of the following is an advantage of the rotating anode over the stationary anode
higher heat capacity
which of the following will decrease beam attenuation
higher kilovoltage
Reducing the amount of scatter radiation reaching the IR results in
higher radiographic contrast.
The patient body habitus indicative of an increased patient thickness is:
hypersthenic
the device that receives the radiation after it exits the patient is the
image receptor
Direct radiography eliminates the need for the ________________ because the image is captured by multiple sensors that create an image signal immediately.
image receptor cassette
An image that can resolve 10 Lp/mm instead of 6 Lp/mm is said to have
improved sharpness
what is the result of under-penetration
inadequate information
increasing the pixel bit depth will
increase contrast resolution
which of the following is considered a cardinal rule of radiation protection
increase distance from the source
what is the most likely cause of the change in the emission spectrum represented by the purple line
increase in kVp
How is the primary beam affected when increasing the tube filtration?
increase in the proportion of higher-energy x-rays
spatial resolution is the ability to
increase matrix size in order to improve image sharpness
what is the most likely cause of the change in the emission spectrum represented by the purple line
increase of mA
To maintain the same exposure to the IR, if the SID is increased, the mAs must be
increased
according the coulomb's law, when the distance between two charges is halved, how is the force between the two charges changed
increased by 4 times
which of the following statements below best expresses the relationship between energy, frequency, and wavelength of electromagnetic waves
increased frequency= decreased wavelength= increased energy
Deciding to use a grid for a radiographic examination requires use of
increased mAs.
Which of the following most accurately describes the relationship between part thickness and x-ray beam attenuation?
increased part thickness causes increased attenuation
Increasing the displayed field of view (FOV) for a fixed matrix size will result in
increased pixel size
factors that decrease x-ray absorption include
increased x-ray beam quality
When the SID is decreased from 72 inches SID to 40 inches SID, how is the radiation reaching the IR affected and does mAs need to be adjusted?
increases radiation to IR; decrease mAs.
Increasing tube filtration
increases the beam energy and decreases radiographic contrast.
Increasing the kVp
increases the energy of the x-ray photons. increases the quantity of x-ray photons. increases the penetrating power of x-ray photons.
what is the purpose of a step-up transformer
increases voltage
during the operation of a step-up transformer within the xray circuit, voltage will ______ and current will _____
increases, decreases
When OID cannot be reduced, it is possible to reduce size distortion by
increasing SID.
spatial resolution can be increased by
increasing the pixel density and decreasing the pixel pitch only
making the digital image appear with low contrast, many shades of gray, is done by
increasing the window width
the compton effect is
independent of Z
In maintaining the same mAs, there is a(n) ________________ relationship between mA and exposure time.
inverse
Which of the following describes the relationship between mA and time to maintain exposure to the image receptor?
inverse proportional
an atom that has been stripped of one or more of its electrons is termed a/an
ion
what term describes the process of removing an electron from an atom
ionization
x-rays can eject electrons from atoms. this is known as:
ionization
A compensating filter
is used for specific anatomic areas. produces a more uniform exposure to the IR. requires an increase in mAs.
what occurs when filtration is placed in the path of the x-ray beam
it absorbs low-energy photons
if a pixel has a bit depth of 10, this means that
it can produce 2^10 shades of gray
why is barium sulfate used as a contrast agent to visualize soft tissues
it has a high atomic number
which is the primary disadvantage of a stationary anode
it heats up too quickly
during the bremsstrahlung interaction, what happens to the filament electron
it is attracted to the nucleus
as two charges get closer together, how is electrostatic force affected
it is inversely proportional to the square of the distance between them
why is molybdenum used in a rotating anode
it is light but strong
when compared to a beta particle, how would you describe an alpha particle
it is much larger
If the phosphor layer in a CR system is considered turbid, this means that:
it is randomly arranged across a support layer
what occurs with the energy of the incident photon during compton scattering
it loses up to 1/3 of its energy
what most often occurs with the xray phton during compton scattering
it removes a middle or outer shell electron
which is true of the xray photon produced during classical scattering
it travels in a different direction than the incoming photon
Size distortion will be affected by which of the following except
kVp
Which of the following exposure factors must be selected on the console which increases the quality and penetration of the xray beam
kVp
which factor has greatest control over the quality of xrays
kVp
which factor primarily controls beam quality
kVp
which of the following directly affects the quality of an xray beam
kVp
which of the following factors affect beam quantity
kVp distance filtration
Which of the following statements is true regarding kVp's role when using digital imaging systems?
kVp ensures adequate penetration of the anatomy
what is the purpose of the focusing cup
keeps the electrons together in a small space
What is the SI unit for mass
kilogram
what is the SI unit for mass
kilogram
a filament electron enters a tungsten target atom with an energy of 70 kVp. it interacts first with an l-shell electron then with a k-shell electron. which of the following are produces
l-characteristic xray production and heat
For a given field of view (FOV), a __________matrix size will result in _________pixels
large more
the purpose of the line focus principle is to create which of the following
large actual and small effective focal spot size
digital image quality is improved with
larger matrix size
which material lines the protective tube housing
lead
which of the following must be limited to <1 mGy/h at a distance of 1 m
leakage radiation from the tube housing
an increase in kVp will have which of the following effects in digital imaging
less photoelectric interactions and exposure rate increased
which device adjusts the incoming power supplied to the xray circuit to maintain 220 V
line compensator
Spatial frequency consists of units of
line pair/millimeter
What type of response does digital imaging have to exposure?
linear
after compton scattering, the scattered xray has
longer wavelength
a radiolucent structure likely has which of the following properties
low atomic number
When the intensities of radiation exiting the patient are very similar, the resulting radiographic image has
low contrast, long-scale contrast
Anatomic tissues that attenuate the x-ray beam equally are said to have
low subject contrast
which operating console choice selects large or small filament
mA
Which of the following is true regarding the effect of mAs on the brightness of a digital image?
mAs does not affect brightness in a digital image.
Which of the following is the correct formula for the direct square law formula?
mAs1/mAs2 = (SID1)2/(SID2)2
Which of the following is the correct formula to determine how mAs should be adjusted when different ratio grids are used?
mAs1/mAs2 = grid conversion factor1/grid conversion factor2.
what does a charged particle in motion create
magnetic field
which conditions and materials are necessary for mutual induction to occur
magnetic flux and a solenoid
which term is used to describe a material able to attract iron, cobalt, or nickel
magnetism
size distortion is also called
magnification
which term describes the breakage of the major structure and framework of the macromolecule as a result of an xray interaction
main-chain scission
what is the main purpose of the glass or metal enclosure
maintain a vacuum within the tube
in digital radiography, spatial resolution is improved with increased
matrix size
atoms and molecules are fundamental building blocks of
matter
what is signal-to-noise ratio
method used to express noise in comparison to signal strength
which exposure factor, controlled by the radiography console, primarily regulates the number of electrons available to produce xray photons
milliampere (mA)
what is a measure of the imaging system's ability to display the contrast of anatomic objects varying in size
modulation transfer function
which device converts electrical energy into mechanical energy
motor
what is the purpose of grounding
neutralizes an object
Increasing the mAs (within reason) has ____________ effect on brightness displayed in digital imaging.
no
Which of the following reduces contrast resolution
noise
which of the following events will not occur in the diagnostic range of xray energies
none of the above
With digital imaging, the relationship between mAs and image brightness is
none of these
on which day did roentgen first discover x-radiation
november 8, 1895
which describes the force that holds the protons and neutrons together in the nucleus
nuclear binding energy
what is pixel density
number of pixels in a given area
who introduced the idea that electricity flowing through a conductor could produce a magnetic field
oersted
The Hurter and Driffield (H & D) curve for digital imaging is linear rather than s-shaped because:
of a wider dynamic range
which is the unit for resistance
ohm
which law states that the voltage is equal to the product of the current flowing through a conductor and the resistance of that conductor
ohm's law
which law states that the voltage is equal to the product of the current flowing through a conductor and the resistance of the conductor
ohm's law
the intensity of the xray beam is less
on the anode side
what could be considered 100% contrast
one black pixel and one white pixel
Which PACS storage option offers the fastest retrieval of data?
online
at what point in the interaction chain of events is a characteristic photon produced
outer-shell electron filling inner-shell vacancy
what error does digital imaging have the most latitude for
over-exposure
which interaction requires 1.02 MeV of energy
pair production
which interaction results in a positron and an electron being emitted
pair production
which type of circuit has elements arranges like a bridge or branching across a conductor
parallel circuit
assuming all other factors are accurately adjusted, the exposure time with AEC is adjusted to accommodate changes in
patient anatomy
in an automatic exposure control system, the detectors are placed between the
patient and the IR
the greater the absorption of radiation, the greater the
patient dose
which factors impact the detail of a radiographic image
patient factors, focal spot size, anode angle
Amorphous silicon is used as the
photodetector for indirect capture DR imaging
Amorphous selenium is used as the
photodetector for indirect capture DR imaging.
a photon of 10 MeV colliding with a nucleus will likely result in what type of interaction
photodisintegration
positive contrast media is administered to increase what type of interactions
photoelectric
when the kV selected is equal to or slightly greater than the inner-shell binding energy of a target tissue atom, which interaction predominates
photoelectric
what interaction in the diagnostic range involves the total absorption of the incident photon
photoelectric effect
differential absorption occurs because different tissues have varying amounts of
photoelectric interactions
At the time of processing, the energy of the trapped electrons is released by exposure to a laser in a process called
photostimulable luminescence
Computed radiography screens respond to radiation with _____.
photostimulable luminescence
The emission of light by a phosphor, when exposed to a laser, is known as ________.
photostimulable luminescence
When processing the PSP plate, the analog signal is digitized and divided into a matrix of squares. Each square is a
picture element (pixel).
In digital imaging, which of the following determines the range of grayscale available for display
pixel bit depth
the distance from the center of one pixel o the center of the one next to it is
pixel pitch
the distance or spacing from the middle of one pixel to the middle of an adjacent pixel is known as what
pixel pitch
in digital radiography, the brightness of the image is determined by
pixel values
which beam is found leaving the collimator and exposes the patient
primary beam
where is the autotransformer located
primary circuit
where is the timer circuit located
primary circuit
which of the following reduces leakage radiation to required standards
protective housing
what is the primary purpose of the glass envelope
provide a vacuum
in producing a radiographic image, which of the following occurs first
quality and quantity of x-ray beam exit the x-ray tube
the area under the curve of the xray emission spectrum represents
quantity
what is mA directly proportional to in regard to the xray beam
quantity
the curie is an expression of
quantity of radioactive material
what is the result of under-penetration
quantum noise
in producing a radiographic image, which of the following occurs last
radiation interacts with IR
which is the process of a radioactive element giving off excess energy and particles to regain stability
radioactive decay
what device allows current to flow in only one direction
rectifier
what is located in the xray circuit between the high-voltage transformer and the xray tube
rectifiers
what is the purpose of beam filtration
reduce patient dose
As the kVp is increased, what happens to the subject contrast?
reduction in subject contrast PreviousNext
the heel effect
requires the cathode to be positioned to the thicker anatomy
Digital imaging preprocessing includes
rescaling and histogram analysis.
place the following events leading to the production of xrays in order from first to last
resistance is adjusted at the rheostat filament current is increased filament is heated electrons are boiled off filament
to measure resolution, a _______ is necessary
resolution test pattern
a small anode target angle
results in an increase in anode heel effect
all of the following xray circuit devices are located between the incoming power and the primary coil of the high voltage transformer except
rheostat
which is an adjustable form of a resistor
rheostat
Which of the following results in a poor-quality digital image because of improper processing due to extreme over-exposure to the image receptor
saturation
when a digital image is excessively overexposed, what is the result
saturation
A material that absorbs x-ray energy and emits visible light in response is a
scintillator
Which of the following is used by both forms of indirect cassetteless systems?
scintillator
where are the rectifiers located
secondary circuit
which material can both conduct electricity and act as an insulator
semiconductor
when the image of a structure appears shorter than the actual structure there is
shape distortion
Focal spot size affects only
sharpness
the overall quality of the radiographic image is determined by
sharpness visibility of anatomic structures accuracy of structural lines ALL OF THE ABOVE
A quality radiograph must include
sharpness (resolution) visibility of anatomic structures accuracy of structural lines displayed
which unit of measure is used to quantify occupational exposure or dose equivalant
sievert
which of the following is a method of describing the strength of the radiation exposure compared with the amount of noise apparent in a digital image
signal-to-noise ratio
on which does the size of the actual focal spot depend
size of the filament
which of the following is correct regarding spatial frequency
small objects have higher spatial frequency and large objects have lower spatial frequency only
which is true of line focus principle
smaller anode angles creates better image detail and more heel effect
what occurs if the number of pixels in a matrix decrease and the FOV remains the same
spatial resolution decreases
what occurs if the number of pixels in a matrix increases and the field of view remains the same
spatial resolution increases
Whenever magnification is increased
spatial resolution is decreased
which is an advantage of angling the rotating anode
spreads the heat generated over a larger area of the anode
what part of the induction motor is located outside of the glass envelope
stator
which of the following is composed of electromagnets arranged within a tube housing outside of the glass envelope
stator
which portion of the induction motor is made of electromagnets
stator
which are a part of an AC induction motor
stator and rotor
which are part of an AC induction motor
stator and rotor
a transformer with 250 turns in the primary and 50 in the secondary would be a
step-down transformer
which type of transformer has 100 turns on the primary side and 50 turns on the secondary side
step-down transformer
PAC's primary use is to:
store digital images
The part of a PSP plate that includes columnar crystals, resembling needles on end, is the
structured phosphor layer
a change in which factor would result in alterations to the x-ray emission spectrum s x-axis, y-axis, and location of the discrete line
target material
how are magnetic field strength measured
tesla
Histogram analysis compares the histogram with pre-established histograms specific to
the anatomic part being imaged
when characteristic xrays are produced, the energy of the xrays is characteristic of
the atomic number of the target
the overall energy of the characteristic x-ray photon depends on
the binding energy of the inner-shell electron the energy level of the filament electron the shell of the electron that is dropping into the vacancy
The histogram is
the digital radiographic image and a graphic representation of a data set.
Which of the following controls brightness of a digital system.
the display monitor
Digital imaging quality control focuses on
the display monitors and the viewing environment.
what does beam quality refer to
the energy level of the radiation
the probability that an xray will interact with an outer-shell electron is influenced principally by
the energy of the incident xray
how do xrays and gamma rays differ
the energy sources that produces them
what has or will occur if a filament electron enters the tungsten atom with 80 keV of energy and leaves the atom with 75 keV of energy
the filament electron traveled very far from the nucleus
With digital imaging, if the kVp is too high.
the image brightness appears appropriate
With digital imaging, if the image receptor is not exposed to enough radiation
the image brightness will appear appropriate.
which refers to the relationship between the actual focal spot size, the effective focal spot size, and the anode target angle
the line-focus principle
the incident photon interacts with which of the following during photodisintegration
the nucleus of the atom
how is an atomic number of an element determined
the number of protons in the nucleus
the xray emission spectrum is a plot of
the number of xrays versus energy
transmission refers to
the process of sending the x-ray beam through the patient
as xray energy increases
the ratio of compton to photoelectric interactions increase
how is half-life defined
the time it takes for half of remaining atoms in an amount of a radioactive element to decay
causes of tube failure are most often related to which of the following
thermal characteristics
alpha and beta particles are similar to xrays and gamma rays in what way
they have the energy to ionize matter
which is true of electromagnetic waves
they travel at the speed of light
which of the following will increase beam attenuation
thicker anatomic part
what metal is added to the filament to increase thermonic emission and extend tube life
thorium
The placement of several CCD detectors close together to form a larger detector is called
tiling
matter per unit volume defines
tissue density
The amount of remnant radiation will decrease when increasing:
tissue thickness
Typically, every increase in the thickness of the part being imaged of 4-5 cm requires the mAs
to be doubled
Detective Quantum Efficiency (DQE) is used:
to measure a phosphor's ability to convert x-ray energy to an output signal
quantum noise is a result of
too few x-ray photons reaching the image receptor
when taking an image of the humerus, where should the cathode side of the tube be directed
toward the patient's shoulder
radiation interacting with air is more likely to be _____________, resulting in that area of the image being darker
transmitted
The purpose of europium in the photostimulable phosphor is to:
trap metastable electrons
Increasing the signal-to-noise (SNR) increases the visibility of anatomic structures
true
The exposure indicator (EI) of a digital imaging system provides a numeric value that corresponds to the radiation exposure to the image receptor
true
electromagnetic radiation has properties of a wave and a particle
true
the higher the detective quantum efficiency of a system, the lower the radiation exposure required to produce a quality image
true
the process of differential absorption to form an image is the same for digital, film-screen, and fluoroscopy
true
the resolution of the monitor used to display the digital image has an enormous effect on spatial resolution
true
the spatial resolution of a digital image is determined by the pixel size
true
the x-ray beam is an analog wave form
true
total absorption of the incoming x-ray photon is the result of the photoelectric effect
true
when image is distorted, spatial resolution is also decreased
true
what factors can affect the total number of photons produced inside the tube at the target anode
tube current, target material, and kVp
how many filaments does a typically radiographic tube have
two
how many lines are in a line pair
two
a dual focus tube refers to a tube with
two filaments
a dual-focus system has
two filaments of differing size
what is the equation for velocity
v=d/t
Display device performance is determined by use of
various test patterns.
Primary workstation displays are used for
viewing the image for the first time.
which term is the electromotive force or potential energy that produces electron movement
voltage
place the following events leading to the production of xrays in order, from first to last
voltage is adjusted at the autotransformer voltage goes to primary side of the step-up transformer kilovoltage leaves the step-up transformer alternating current is converted to direct current
which of the following practices extend tube life
warm up the tube as appropriate press the prep and exposure switches at almost the same time avoid using very high exposures or long exposure times
when considering the wave properties of electromagnetic radiation, what is the distance from the peak of one wave to the peak of the next wave
wavelength
when are brems photons produced
when an electron's kinetic energy is lessened by its attraction to a target nucleus
In digital imaging, the reason(s) mAs does not affect brightness is/are:
wide dynamic range and computer processing
why can an acceptable image be produced with CT or flat-panel digital radiography equipment when the input exposure was underexposed or overexposed
wide dynamic range of the digital detector
why can an acceptable image be produced with computed radiography (CR) or digital radiography (DR) equipment even when the input exposure was underexposed or overexposed
wide dynamic range of the digital detector
The post-processing method used to allow us to see all shades of gray in an image is referred to as
window and level
the midpoint of the range of brightness levels visible on the digital image is determined by
window level
to alter image brightness, the _______ is changed
window level
to alter image brightness, the ________ is changed
window level
During digital image display, the contrast can be lowered (decreased) by increasing ___________.
window width
what adjusts the range of densities displayed on the monitor
window width
Detective Quantum Efficiency (DQE) is a measure of
x-ray absorption efficiency
what term defines the total number of x-rays photons in a beam
x-ray quantity
which of the following electromagnetic radiation has the highest frequency
xray
the effective focal spot is the
xray beam as seen from below the tube
the xray tube is a part of the
xray circuit secondary
which of the following contribute to inherent filtration
xray tube permanent enclosure, xray tube window
which is true if less ripple is present
xrays are produced with more consistent energy
what is the pixel size in mm of a 256x256 matrix with a 10 cm^2 FOV
.39
what is the pixel size of millimeters of a 512 matrix with a 30 cm field of view
.60
Standard radiographic x-ray tubes have small focal spots that measure approximately
0.5-0.6 mm.
place the following events leading to the production of xrays in order, from first to last: 1 resistance is adjusted at the rheostat 2 filament is heated 3 filament current is increased 4 electrons are boiled off filament
1 3 2 4
what is the minimum amount of energy of xray photon must have to create a pair production
1.02
Approximately what percentage of the removed electrons are "trapped" in the conduction band?
1%
approximately how much of an electron's kinetic energy is used to produce xrays
1%
what is the medium amount of energy an xray photon must have to create a pair prodution
1.02 meV
What is the magnification factor when using a 72-inch SID and 1.5-inch OID?
1.021
a diagnostic xray photon has a frequency of 2.42 x 10^19 Hz. what is its wavelength
1.24 x 10^11 m
how much activity will remain in a dose of 20 mCl 99m TC after 24 hours
1.25 mCi
the calculate the heat units generated by a three-phase six-pulse xray unit, which formula could be used
1.35 x time x mA x kVp
one half-value layer (HVL) reduces the intensity of the x-ray beam to _____ of its original
1/2
the average energy of most brems photons are ____ of the kVp selected on the control panel
1/3
the average energy of most brems photons are _____ of the kVp selected at the control panel
1/3
if the distance from the source is doubled, the quantity of radiation reaching a specific area is _____ the original
1/4
Which of the following exposure factors produces the same amount of remnant radiation as does 20 mAs at 70 kVp?
10 mAs @ 81 kVp
How much mAs is produced when the mA is 200 and the exposure time is 0.5 s?
100 mAs
by regulation, xray tube leakage radiation can be no more than
100 mR per hour at a distance of one meter
single-phase full-wave rectified current has what percentage of ripple
100%
which technique 108 kV and 10 mAswill produce the greatest number of photodisintegration events in an average abdomen
108 kV and 10 mAs
the intensity of radiation at a distance of 3 m from the source is 48 mR/h. what is the intensity when the distance decreased to 2 m
108 mR/h
If a high-voltage transformer has 100 primary turns and 50,000 secondary turns and is supplied by 220 V and 100 A, what are the secondary voltage and current
110 kV
what is the energy of an xray photon produced when an o-shell electron fills an l-shell vacancy
12.02 keV
If 10 mAs produce appropriate IR exposure at 40 inches SID, how much mAs is needed at 48 inches SID to maintain that amount of IR exposure?
14 mAs
to increase the quantity of radiation by adjusting the kVp to the same level as doubling the mAs, you need to increase kVp by a fact of what percentage
15%
The relationship between kVp and the quantity of remnant radiation is known as the
15% rule
What is the velocity of an object moving 80 m in 3 seconds
16 m/s
a patient was radiographed at 40 SID and received 22 mR. if the SID was increased to 44 SID, what is the new dose
18 mR
If a radiographic image has to be repeated because of an exposure error, the mAs must be changed by a factor of at least
2
how many half-value layers will it take to reduce an x-ray beam whose intensity is 78 R/min to an intensity of less than 10 R/min
2
what does an alpha particle consist of
2 protons and 2 neutrons
which of the following matrices will have greater spatial resolution
2048 x 2048
If the intensity of radiation at 36 inches SID is 600 mR, what is the intensity if the distance is increased to 60 inches SID?
216 mR
How much mAs is produced when the mA is 800 and the exposure time is 30 ms?
24 mAs
in a tungsten-targeted xray tube operated at 90 kVp, the most abundant xrays would be at
30 keV
how many revolutions per minute does an induction motor turn the rotor of a general purpose xray tube
3400
at a 72-inch focal subject distance, the intensity of the xray beam is 10 mr/hr. if the intensity is changed to 40 mr/hr, what is the subsequent focal-object distance
36 inches
a technique of 80 kV, 400 mA, 0.8 seconds is to be used on a 3-phase, 12-pulse machine. how many heat units are produced with a single exposure
36096
how many heat units are produced with an exposure using a single phase xray unit, 75 kVp, and 50 mAs
3750 HU
what is the velocity of electromagnetic radiation
3x10^8 m/s
what is the voltage ripple associated with a 3-phase, 12 pulse rectified generator
4%
if there are 100 turns in the primary side of the transformer and the current is 100 mA, what is the current if the turns in the secondary side of the transformer are 25
400 mA
if at a 40-inch distance, the xray tube is delivering 100 m/hr to the patient, what would the intensity be if the xray tube were moved to a distance 20 inches from the patient
400 mR/hr
If the dynamic range of an imaging system is 12 bits, how many shades of gray are available
4096
during a photoelectric interaction of an atom of barium, the photoelectron's kinetic energy is observes to be 12 keV. the binding energy o the k-shell electron is 37.44 keV. calculate the energy of the incident photon
49.44 keV
What is the acceleration of the javelin if the initial velocity is 0, the final velocity if 15 m/s, and the time of travels in 3 seconds
5 m/s^2
50 mr/hr is delivered to the patient at a 40-inch distance. what would the patient to xray distance be if the intensity was changed to 25 mr/hr
57 in
what is the energy of an xray photon produced when a l-shell electron fills a k-shell vacancy
57.4 keV
which describes the electricity provided to the radiology department
60 Hz AC
what type of current is provided to the radiology department circuit
60 hz AC
a filament electron removes a K shell electron and an M shell electron fills the vacancy. The K shell binding energy is 69.5 keV and the M shell binding energy is 2.8 keV. What is the energy of the K-characteristic photon produced
66.7 keV
a technique of 50 kV, 100 mA, 0.1 seconds is to be used on a 3-phase, 6-pulse machine. How many heat units are produced with a single exposure a. 500 b. 675 c. 705 d. 820
675
what is the energy of an xray production produced when an o-shell electron fills a k-shell vacancy
69.42 keV
What is the velocity of a baseball that travels 15 meters in 2 seconds
7.5 m/s
A diagnostic image was produced using a 70 kVp, 15 mAs at 40-inch SID. Which of the following exposure techniques would maintain the exposure to the image receptor when decreasing the SID to 30 inches?
70 kVp at 8.4 mAs
which is the atomic number for tungsten
74
with a 75 kVp exposure, the energy of the photons displayed on the continuous emission spectrum can range from just above 0 keV to what value
75 keV
how many electrons can the l shell hold
8
what resolution will result in greatest spatial resolution
8 lp/mm
A diagnostic image is created using 80 kVp, 10 mAs, and a grid ratio of 12:1. Which of the following exposure techniques would maintain exposure to the image receptor when the grid is removed?
80 kVp at 2 mAs
if the distance from the source is changed from 72 inches to 36 inches and the original beam intensity was 200 mR, what is the new intensity
800 mR
what is the energy of an xray photon produced when an m-shell electron fills an l-shell vacancy
9.28 keV
How much force is needed to move a 30-kg piece of equipment at a rate of 3 m/s^2
90 N
when electrons strike the anode, how much of their energy is concerted to heat
99%
The device that is needed to allow computer processing of an analog signal is a/an:
ADC
Which component of the CR reader digitizes the signal?
ADC
What is described as the rate of change in velocity over time
Acceleration
What is potential energy
An object's stored energy
If the mA is 600 and exposure time is 10 ms, how can the mAs be doubled?
Any of the other answers is correct
What does ALARA mean
As Low As Reasonably Achievable
