Physics

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

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


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