Study sets, textbooks, questions
Upgrade to remove ads
Final Exam Review
XRAY 1042- Radiographic Quality
Terms in this set (243)
Digital imaging processing is
computer manipulations applied to the digital images
A combination of rows and columns of pixels
the size of a pixel is measured in
The number of bits that determines the amount of precision in digitizing the analog signal and the number of gray shades that can be displayed in the image is the:
the pixel bit depth determines the image's
the number of pixels per unit area is called
the pixel spacing or distance measured from the center of a pixel to an adjacent pixel is called
the measure of the imaging system's ability to display the contrast of anatomic objects varying in size is
Modulation transfer function (MTF)
it collects, amplifies, and converts visible light to an electrical signal
photomultiplier tube (PMT)
in the CR reader unit, the IP is scanned with a
helium-neon laser beam
how often the analog signal is digitized is the
The distance between the analog points being sampled is the
it can be removed from the Bucky and is used tabletop
The DR detector array is typically located
Where you would normally find the Bucky tray
DR imaging systems briefly store the electrical charge in the
The ability of the detector to accurately capture the variety of photon intensities in the remnant radiation is
The measurement of the efficiency of an image receptor in converting the x-ray exposure it receives to a quality radiographic image is the
detective quantum efficiency
A method of describing the strength of the radiation exposure compared with the amount of noise apparent in the digital image is the:
A method of describing the contrast resolution compared with the amount of noise apparent in a digital image is the
What is not accomplished through the histogram analysis?
Manipulation of image contrast
histogram analysis represents this for different exposure levels
incidence of pixels
The range of the histogram data set that should be included in the displayed image is determined by the
the numerical value indicating the level of radiation exposure to the digital IR is the
a value that reflects the difference between the desired or target exposure to the IR and the actual exposure to the IR is the
deviation index (DI)
this provides a method of altering the image to change the display of the digital image
An example of a scintillator used in an indirect conversion detector is
gadolinium oxysulfide, cesium iodide
the indirect conversion detector uses
a scintillator, a photodetector
the computer system designed to distribute, store, and display digital images is
what megapixel should diagnostic interpretation monitors have
the communication standard for sharing between PACS and imaging modalities is
What is the term generally used to describe the emission of light from a substance as the result of stimulation by radiation?
The CR phosphor layer is composed of
barium fluorohalide with europium
The emission of light when stimulated by a high-intensity laser beam is
This part of the plate reflects light released during the reading phase toward the photodetector
Where is the PSP plate located?
on the inside of the cassette
The part of a PSP plate that reduces and carries away static electricity is the
The part of a PSP plate that gives some rigidity to the plate is the
the part of the reader that senses the light released from the PSP plate is the
The part of the reader that consists of a laser, optical filters, light-collecting optics, and beam-shaping devices that is designed to project and guide a precisely controlled laser beam back and forth across the plate as the plate moves through the scan area is the
This part of the reader moves the PSP plate through the reader.
part of a DR system with indirect capture, the light-sensitive device that is commonly found in digital cameras is the
charged-coupled device (CCD)
A material that absorbs xray energy and emits visible light in response is a
the scintillator for the indirect capture DR system that utilizes a CCD is
The placement of several CCD detectors close together to form a larger detector is called
The two methods for indirect capture in DR include
charged-coupled devices, scintillator and TFT arrays
Amorphous silicon is used as the
photodetector for indirect capture DR imaging
On the histogram, the _____ represents the amount of exposure and the _____ the incidence of pixels for each exposure level
the range of exposures that produce acceptable information to be used in image formation is
in CR this represents the exposure level to the PSP plate
Amorphous selenium is used in the
photoconductor for Direct capture DR imaging
the value that indicates exposure to the IR with a DR imaging system is the
dose-area product (DAP)
Related to the DR detector, this is an expression of the potential "speed class" or radiation exposure level that is required to produce an optimal image
detective quantum efficiency (DQE)
digital imaging quality control focuses on
the display monitors, the viewing environment
display device performance is determined by use of
various test patterns
This test assesses the system's ability to display images of different parts of an image with high fidelity
the test assesses the displayed luminance values versus the input values from the display system
Part of the direct-capture DR system, the __________ absorbs x-rays and produces an electric signal
Which of the following describes the extra step, and is therefore a limitation, of indirect-capture methods?
xrays are converted to light and then to electrons
The artifact seen in CR imaging systems that is caused by insufficient mAs is:
Production of a grainy, reticulated image that cannot be corrected in digital post-processing is the result of:
failure to use high enough mAs setting
an artifact that occurs during the image acquisition phase due to incomplete image plate erasure is called
an artifact that is imaged within the patient's body is a
The image of a gold necklace in the area of interest appears light or bright. This is a ________________ artifact.
an artifact can be...
an object that is not part of the radiographed anatomy, patient motion, an improper grid or warped cassette
what can cause image blur on the finished radiograph
Artifacts are an acceptable part of digital imaging. (T or F)
Cassettes used in computed radiography are more highly sensitive to background and scatter radiation than film/screen cassettes are. (T or F)
A ghost (phantom) image can occur in digital imaging because of what
The accuracy of the anatomic structural lines recorded in the radiographic image is determined by the:
to what does the term "unsharpness" refer?
The amount of poor resolution of detail at the edges of structures that shows up on a radiograph
What is true of the focal spot (which is where x-rays originate)?
The smaller the focal spot, the less unsharpness on the radiograph
Which three geometric factors affect resolution of detail?
The size of the focal spot, SID, and OID
What is the biggest obstacle to producing radiographs with sharp resolution of detail?
Which of the following provides the best results in a radiographic examination?
the smallest focal spot possible, the longest SID, and shortest OID
what could help minimize blur caused by involuntary patient movement
use short exposure time
What should you be most concerned about when evaluating radiographs for resolution of detail?
how sharply the anatomic structures are recorded
A smaller focal spot will produce which of the following?
Patient motion is the biggest challenge facing the radiographer trying to produce radiographs with sharp resolution of detail, because motion causes blur. What is the most serious consequence of a blurry image?
The need to redo the exam and expose the patient to more radiation
The blurring caused by geometric factors at edges of structures on a radiograph is which of the following?
Digital imaging requires that the spatial resolution frequency signal be sampled how many times from each cycle?
The "sampling" mentioned in the above question is referred to as what?
The ________ represents a depth to the information in the digital image.
The best method for controlling motion when the patient is unable to cooperate is to:
maintain mAs, while decreasing time
A body structure farther from the central ray will look smaller on the image than one closer to it. (T or F)
The distance between the object being radiographed and the IR is the
The distance between the radiation source and the image receptor is the
The SOD can be determined by
subtracting the OID from SID
What is it called when the image of a radiographed object or a part of the body is misrepresented either in size or shape?
Generally, which of the following is true of a long SID (source-to-image receptor distance) and a short OID (object-to-image receptor distance)?
it minimizes magnification
What is true about distortion?
Distortion can be reduced by careful positioning
what is true of magnification
it always occurs
Positioning an extremity parallel to the image receptor and perpendicular to the x-ray beam helps minimize what?
When might the central ray be intentionally off-centered from the anatomy being examined?
magnification is also referred to as which of the following?
when is an object magnified more?
when it is closer to the source
as the amount of magnification decreases, what happens to the level of spatial resolution on a radiograph?
In certain special circumstances you may want to angle the tube intentionally to avoid superimposing one structure on another in the image (T or F)
In radiography, how will body parts that are positioned farther away from the image receptor appear, as compared with those closer to it?
When referring to shape distortion, what does elongation mean?
an image is lengthened or extended
To get a good quality radiograph, how must the central ray be positioned in relation to the object and film?
why is there some magnification in all radiographs?
OID cannot be reduced to zero
The central ray should always be directed at the center of the image receptor (T or F)
which will produce the largest image
40" SID, 5" OID
If all other factors remained the same, increasing the SID would have what effect on image receptor exposure?
which of the following does mA control?
the number of xray photons produced in the tube, determines the exposure rate
how does doubling the mAs affect the exposure rate?
doubles the exposure rate
Which of the following is true when the exposure time is longer?
The number of photons emitted by the x-ray tube is larger
what part of the body absorbs the most xrays?
how is mAs calculated
mA in milliamps multiplied by time in seconds
If the exposure time is cut in half, how must the mA be adjusted to maintain the same image receptor exposure?
The quantity of xrays produced is dependent upon which of the following?
How many millimeters of Al is recommended for standard X-ray equipment?
Which factor influences the average energy of photons reaching the image receptor?
The degree of penetration by an x-ray photon depends upon which of the following?
density of the object, thickness of the object
Certain materials, due to their density, will readily allow passage of x-ray photons. These materials are classified as
Which of the following body tissues would have the highest absorption coefficient when exposed to diagnostic x-ray photons?
The differential attenuation of a structure is related to the ______________ of the tissue.
atomic number, thickness, density
The histogram generated from the image data allows the digital system to find the
minimum, maximum signal and shades of gray
Due to the Anode Heel Affect the _______________ end of the tube has more penetrating power.
what is a histogram
a graphic representation of xray exposure
Which of the following describes the digital processing that produces changes in brightness?
Selection of the incorrect body part from the examination menu may result in _______________.
Raw data used to form the image histogram are compared with ____________________
a normal histogram referenced by the computer
Contrast is defined as which of the following?
the difference between adjacent areas of density in a radiograph
the kVp determines what
the penetrating ability of the xray beam and the quality of the beam
subject contrast refers to what?
the different densities visible on a radiograph due to patient anatomy
what is true of using a contrast medium
it helps produce a radiograph with a high subject contrast
Contrast displays a range of densities (white, shades of gray, and dark tones) that make it possible to do which of the following?
see the body structures
The factor(s) that make a difference in the amount of radiation absorbed, and therefore in the subject contrast, are which of the following?
Which of the following is true of source-image receptor distance?
it has no direct impact on contrast
which of the following factors would be used to control contrast
what affect subject contrast?
size of pt and type of tissue
How would an image with just a few, wide density differences be described?
which is describes a short scale of contrast?
if you have high kVp you have
How will an increase in radiographic fog affect contrast?
contrast will be lower
The number of density differences in a radiograph refers to which of the following?
scale of contrast
what describes a long scale of contrast?
Increasing kVp will result in which of the following?
increasing photon energy
How will an air gap technique affect radiographic contrast?
produce higher contrast
The concept of contrast as it is displayed on a soft-copy display monitor for digital images is described as:
Contrast evaluation can be made only when sufficient image receptor exposure exists. (T or F)
The primary method for adjusting contrast with digital imaging systems is through window width manipulations. (T or F)
Which of the following will have the greatest effect on radiographic contrast?
eliminating scatter radiation
Why is contrast needed in a radiographic image?
Makes detail visible
Muscle tissue absorbs more radiation than fat tissue because muscle tissue has a:
higher tissue density
What contributes to subject contrast?
differences in tissue thickness and density and atomic number
Allows visibility of anatomic structures
how does a cone function?
by focusing the beam into a narrow, more concentrated conelike shape
what is true of the aperture diaphragm
it limits the amount of radiation reaching the patient
what is true about how a radiologic technologist can control a collimator
both sets of shutters can be moved to control width and length
what is true of the light field and the radiation field in a collimator
they should be the same size
what are the basic parts of a collimator
light source, mirror, and shutters
the mirror inside the collimator does which of the following?
reflects the light beam to the same area as the radiation beam
the position of the central ray is determined by what
the collimators crosshairs
what is true of a positive beam limitation (PBL)
it ensures the field size is never larger than the image receptor, it works automatically to determine film size being used
how does the PBL device affect the size of the radiation field
it automatically limits it to the field size
even when using a PBL device, what must the radiographer determine
the field size and the IR are limited to the area being examined
What is a common use for cones and cylinders?
what is a lead blocker?
a lead sheet positioned behind the patient to help control scatter
using a larger field size spreads the radiation out more and therefore decreases scatter (T or F)
When a beam restricting device is used, technical factors may need to _______ to compensate for the change in image receptor exposure.
When kilovoltage is increased with no other changes in technical factors, fewer scattered photons will result. (T or F)
Significant collimation requires an increase of _____________ of the mAs
The larger the x-ray beam field size, the _________ the amount of scatter radiation produced
The unrestricted primary beam produces a(n) _________ area of exposure
Which beam restriction device can be cut to the size needed?
an aperture diaphragm
A beam-restricting device that has two or three sets of lead shutters is a(n):
what are the basic parts of a collimator?
light source, mirror, and shutters
What does the mirror inside the collimator do?
Reflects the light beam to the same area as the radiation beam
A light-localizer in a collimator works with which of the following?
a light source and mirror
The beam-restriction device that results in images with the most unsharpness around the edge of the image is the
The two major factors that affect the amount of scatter radiation produced and exiting the patient are
volume of tissue irradiated and kVp
the grid is located
between the patient and the IR
the material between the lead strips of a grid must be
the number of lead lines per inch or cm is the grid
The relationship between the height of the lead strips and the distance between them is the grid
a linear grid
has lead strips in one direction, is the most common type of grid
grid(s) with lead strips that run parallel to each other
a focused grid's lead strips are angled to match
the angle of the xrays in the primary beam
the distance between the grid and the convergent line is the
an IR that has a grid permanently attached to its front surface is a
the type of grid that is usually taped to the front of an IR is a
The type of grid that is permanently mounted but includes a channel for the IR to slide into is the
The grid is part of a device located just below the tabletop that also includes a tray to hold the IR. This device is the
a short dimension grid
has lea strips running perp. to the long axis of the grid
absorption of transmitted photons by a grid caused by misalignment is
what is found between the lead strips in a grid
A radiographic grid should be used whenever kVp exceeds which of the following?
When should a grid be used? 1. when radiographing body parts greater than 10 cm 2. when using a high kVp 3. when scatter radiation is high
all of the above
grid frequencies can range from
25 to 80 lines per centimeter
Grid ratio can be expressed mathematically as:
height of lead strips divided by distance between them
what is true when a grid is used?
less scatter reaches IR, better image contrast, and somewhat higher exposures needed
Which automatic exposure device works by using a gas-filled chamber?
Which automatic exposure device works by converting x-ray photons first into light and then into an electronic signal?
Where is the sensor located in an automatic exposure device with a gas-filled chamber?
in front of the IR
Where is the sensor located in an automatic exposure device that converts light into an electrical signal?
behind the IR
what describes the shortest exposure time required for the AEC device to operate?
minimum response time
Which of the following is a system that allows the radiographer to select a particular button on the control panel that represents an anatomic area and displays a preprogrammed set of exposure factors?
Anatomically programmed technique
What is the purpose of setting a backup time/mAs?
To prevent excessive exposure of the patient
the mAs readout reports what
the actual mAs used for an exposure
Where does a radiographer find the established guidelines for selecting exposure factors for a radiographic examination?
What are calipers used for?
To measure the part
Which of the following is not part of a standardized technique chart?
What kind of chart uses a kVp value that is high enough to adequately penetrate the part but does not diminish radiographic contrast?
a fixed kVp technique chart
there is typically how many AEC detectors in place
an ionization chamber is a hollow cell that contains
phototimer AEC detectors are usually exit-type devices because
the xrays must exit the IR to get to the detectors
Ionization chamber AEC detectors are entrance-type devices because the x-rays must
enter the detector before getting to the IR
these can be adjusted to increase or decrease the amount of radiation needed to terminate the exposure using AEC
when using AEC, the kVp
is set as appropriate for the study
Which of the following is the most critical aspect of successfully performing an examination using AEC?
centering the anatomy of interest over the detector
When the radiographer has the opportunity to set the back-up time, it should be approximately _____________ of the expected exposure time
What effect does the level of mAs have on image brightness when using digital image receptors?
does not directly affect image brightness
Increased quantum noise is seen in a digital image with:
severely lower than needed mAs
The numerical value that is displayed on the processed image to indicate the level of x-ray exposure received on the digital image receptor is the_______________.
Which technical factors affect the exposure to the IR by altering the amount and penetrating ability of the x-ray beam?
In order to reduce patient exposure, _____ kVp and _____ mAs should be used when possible.
a high kVp results in
less absorption and more transmission in anatomic tissues, less variation in the x-ray intensities exiting the patient, increase interactions from Compton scattering, and low-contrast image
During selection of the focal spot size, the radiographer is really determining the:
actual size of the filament used
The distance between the radiation source and the image receptor is the:
The distance between the object being radiographed and the IR is the:
the misrepresentation of the size of an object is
Magnification is affected by:
OID and SID
shape distortion can be created by
Off-centering the central ray and angling the central ray
the SOD can be determined by
subtracting the OID from SID
the property of the xray beam that impacts the unsharpness on the radiograph is beam:
the radiographic grid is located
between the patient and the IR
which is not a primary exposure technique factor?
What type of relationship do mAs have with the quantity of x-rays produced?
Increasing the kVp results in
increases energy, quantity, and penetrating power of xray photons
To adjust the kVp to produce the desired contrast level, the kVp must first be:
high enough to penetrate the part
The inverse square law describes the relationship between _________ and __________.
distance and beam intensity
To maintain the same exposure to the IR, if the SID is increased, the mAs must be:
The mAs/distance compensation formula describes the relationship between ________ and __________.
SID; mAs needed to compensate for changes in SID
The device used to absorb scatter radiation in the radiation leaving the patient before it reaches the image receptor is the
Deciding to use a grid for a radiographic examination requires use of
a compensating filter
is used for specific areas, produces a uniform exposure to IR, requires an increase in mAs
For most pediatric examinations, it is recommended that the kVp
be reduced by 15%
Technique charts typically include information regarding
mAs, kVp, SID
focal spot size affects only
What type of relationship does distance have with x-ray beam intensity?
What type of relationship does mAs have with SID when the goal is to keep the exposure to the IR constant?
Sets found in the same folder
Trauma & Mobile Radiography
radiographic quality - final exam review 2020
radiographic anatomy & positioning II -…
Radiographic Positioning II - Final Exam ((not min…
Sets with similar terms
Ch. 7: Principles of Exposure and Image Quality
Ch. 7: Principles of Exposure and Image Quality
Image Acq- Image processing & quality assurance
Intro ch 7&8 unit 6 E
Other sets by this creator
Endocrine ch 10
Final exam review
Final Exam Review
Other Quizlet sets
Audit Final Chapter 10
cna final review
PP Aerodynamics/Systems Practice Quiz