WorksheetsExposure Exam
Total questions: 98
Worksheet time: 1hrs 5mins
A higher grid ratio:
Decreases image contrast
Requires less exposure
Removes more scatter radiation
Increases image brightness
A higher DQE (Detective Quantum Efficiency) indicates:
Better system efficiency and lower patient dose
Higher patient dose
Greater pixel pitch
More image noise
Which kVp selection would result in the most scattered x-rays in the image-forming beam?
75 kVp
60 kVp
50 kVp
90 kVp
Grid replacement software is designed to
Hide the grid lines from the viewer
Allow the radiographer to select a grid ratio for postprocessing
Create a nongrid image that looks like a grid was employed
All of the above
Digital radiography is best described by which three elements?
Collection, capture, receptor
Capture, signal, receptor
Capture, coupling, and collection
Coupling, receptor, collection
The three primary factors influencing the intensity of scatter in the image-forming beam are:
mAs, filtration, and grids
mAs, kVp, and collimation
Filtration, patient thickness, and mAs
kVp, field size, and patient thickness
Which statement about radiographic grids is incorrect?
A grid is a series of lead strips that alternate with radiopaque interspace strips
The radiopaque strips are typically made of thin lead
Grids may have grid strips running in perpendicular directions
The interspace strips are usually made of aluminum
What operation is applied to small groups of pixels to enhance or smooth the image?
The number of pixels in a matrix and the field of view determines the:
Spatial resolution
Histogram equalization
Window leveling
Geometric correction
X-rays are attenuated:
Based upon the direction of the central ray
Exponentially
Linearly
As a function of mAs
Subject contrast is primarily the result of:
Exposure time
OID
mA settings
Differential absorption
The window level controls image:
Brightness
Resolution
Speed
Contrast
A pixel that has an eight-bit depth displays:
512
256
126
1024
The standard for digital medical imaging and communications is known as:
(a)
Which of the following is a destructive pathology?
Empyema
Sclerosis
Osteoporosis
Tumor
The lead strips in a focused grid are aligned to match the:
The amount of scatter radiation produced increases with:
Decrease in atomic number
Larger field size
Increase in patient thickness
All of the above
Which of the following tissues absorbs the most x-rays?
Bone
Air
Fat
Muscle
Bit depth refers to:
The purpose of moving the grid during exposure is to:
Remove unwanted contrast
Activate the AEC detectors
Blur out the radiopaque strips
Activate the digital detector
CsI/CCD is an indirect DR process by which x-rays are converted first to light and then to an electronic signal.
True
False
The computed radiography cassette is called a(n):
Laser
Thermoluminescent
Optical
Imaging
If the original technique is 25 mAs with an 8:1 grid and you switch to a 12:1 grid, what is the new mAs required?
36 mAs
20 mAs
30 mAs
25 mAs
When performing a KUB on a patient with ascites using AEC and the proper detector combination, the responsible radiographer would:
Decrease the kVp to reduce the amount of Compton
Allow the AEC system to adjust the exposure for the patient condition
Take a scout image using manual techniques
Immediately increase the AEC sensitivity to +2
The dynamic range determines the degree of:
Contrast resolution
Motion blur
Sensitivity
Spatial resolution
What is the definition of attenuation?
Amplification of the x-ray signal
Decrease in patient dose
Reduction in beam intensity after passing through material
Increase in x-ray beam intensity
The ____ the body part, the ____ the attenuation.
More dense; less
Thicker; greater
Thicker; less
Thinner; greater
Which of the following is the greatest attenuator of the x-ray beam?
Psoas muscle
Perirenal fat
Pneumonic lung
Pericardial fat
Which grid would most effectively reduce scatter?
8:1
12:1
6:1
15:1
A device that moves the grid during a radiographic exposure is called a(n):
Potter-Bucky diaphragm
Alternator
Focused grid
Oscillator
The number of grid lines per inch is the grid:
Ratio
Speed
Frequency
Focus
The ratio of the height of the lead strips to the distance between the lead strips is the grid:
Ratio
Selectivity
Speed
Frequency
The primary purpose of using a radiographic grid is to:
Intercept remnant radiation
Remove a percentage of scatter photons
Decrease skin exposure to patients
Remove undesired primary photons
The Moiré effect occurs when:
The tube is angled with the grid
Grid lines run parallel to the scan lines of a digital image
The patient moves during the exposure
The SID is too long
The purpose of an LUT is to:
Apply a predetermined scale of contrast to the digital data set
Determine the exposure index
Create the histogram
Perform geometric processing
The primary source of radiation exposure for occupational personnel is due to:
(a)
A satisfactory radiograph is produced using 6 mAs at 85 kVp without a grid. A second film is requested using an 8:1 grid with a conversion factor of 4. What mAs is needed?
24 mAs
12 mAs
6 mAs
18 mAs
When matrix size is increased and pixel size goes down:
Spatial resolution decreases
Spatial resolution increases
Contrast increases
Both a and c
In an emergency when a grid is unavailable, a way to simulate grid effect is to:
Grid suppression software
Turn the detector over
X-rays transmitted through the patient without interaction contribute to:
Patient radiation dose
Scatter radiation
Useful information
Image noise
As subject density ____, image receptor exposure ____.
Increases; decreases
Increases; remains the same
Decreases; decreases
Increases; increases
__________ refers to the misrepresentation of the size or shape of a structure.
Distortion
Resolution
Magnification
Contrast
All of the following refer to patient factors contributing to image quality EXCEPT:
Receptor contrast
Subject detail
Subject contrast
Tissue density
Total photon absorption leads to ________.
Photoelectric effect
Compton scattering
Pair production
Rayleigh scattering
Basic composition of the liver is ________.
Water
Fat
Calcium
Glucose
6.46 is associated with ________.
Fat
Protein
Carbohydrate
Vitamin
Larger patients impact this negatively: ________.
Subject detail
Image brightness
Scan duration
Contrast resolution
Subject contrast is high in the ________.
Knee
Liver
Brain
Heart
Very low attenuation is associated with ________.
Air
Bone
Muscle
Fat
Reduces image quality: ________.
Compton scatter
Photoelectric effect
Pair production
Bremsstrahlung
A radiographic grid absorbs:
All scatter and secondary electrons
Scatter radiation
Primary radiation
Scatter electrons
A grid is generally employed:
For procedures below 60 kVp
For pediatric studies
For part thicknesses above 10 cm
To improve positioning latitude
The deviation index (DI):
Compares entrance dose to the detector to an established department target dose
Compares DQE and MTF
Compares exit dose to the detector
Compares entrance dose to the patient
Analog to digital conversion involves two steps: quantification and .
(a)
Digital radiographic systems are divided into:
Storage phosphor and PSP
CR and storage phosphor
Direct and indirect conversion
Laser digitizers and selenium plates
The degree of differential absorption is referred to as:
Image receptor exposure
Material contrast
Subject density
Subject contrast
When using a radiographic grid with CR:
The Moiré effect is a consideration
Higher frequency grids are undesirable
Grids are unnecessary
None of the above
Exposure indicators in digital radiography:
All of the following are true of local area processing EXCEPT:
Spatial filtering is local
Electronic magnification is local
It relies on kernels
Kernels are ultimately applied to the entire pixel data set
In CR, the capture element is the:
TFT
Scintillation phosphor
Photostimulable phosphor (PSP)
CCD
Which digital system uses photostimulable phosphor plates?
Flat panel detector
Computed Radiography (CR)
Direct DR
Indirect DR
A condition that increases thickness or tissue density is called an:
(a)
The recorded detail of a structure depends on:
Its position
The body/film relationship
The size of the part
All of the above
A voxel differs from a pixel in that it:
Has only two dimensions
Possesses a third dimension
Controls pixel dimensions
Controls audio volume
The use of a radiographic grid requires:
Attention to CR angulation
Awareness of SID
Increase in exposure
All of the above
The window width controls:
Darkness
Resolution
Contrast
Speed
Image-forming x-rays include those:
When lead strips run in one direction, the grid pattern is:
Criss-cross
Tangential
Linear
Cross-hatched
The luminescence of blue-violet light from a CR fluorohalide, due to laser stimulation:
is directly related to the rescaling process.
is proportional to the x-ray energy exposure.
is inversely related to x-ray exposure.
is not related to the x-ray exposure.
DR panels are particularly vulnerable to:
bodily fluids.
extended exposure times.
sterile fields and temperatures in surgery.
very high kVp values.
Extraneous information not representing the patient is called:
signal loss.
noise.
data drop.
an artifact.
Underexposure using DR detectors will result in:
photon saturation.
quantum noise.
less spatial resolution.
electronic noise.
Indirect DR uses _______ as the photoconductor material:
amorphous selenium
calcium tungstate
gadolinium oxysulfide
amorphous silicon
What is the relationship between CR plate size and spatial resolution?
The best CR spatial resolution is achieved with the smallest size CR plates
Larger CR plates deliver better spatial resolution
Plate size and image resolution have no relationship
Smaller CR plates deliver less resolution due to a lower sampling frequency
In the technology of CR, the latent image is actually:
sensitivity specks in the barium fluorohalide.
electron “holes” in Europium.
the light from the phosphor following laser excitation of the reader assembly.
free electrons in the amorphous silicon.
Increasing mAs decreases image _________, which improves image clarity:
Noise
Contrast
Sharpness
Resolution
All of the following will improve DR radiographic image resolution, EXCEPT:
using lower kVp values.
increasing the SID.
high mA and shorter exposure times.
using a small focal spot.
What is the post-processing function used to eliminate brightness around the image edges called?
Histogram equalization
Electronic annotation
Window leveling
Electronic masking
When adding annotation to a digital image, remember that:
electronic annotation for patient laterality is unacceptable.
all electronic annotation is legally acceptable.
the annotation is a temporary indication of patient condition.
the annotation needs to be added to the exam requisition as well.
Readout of CR data is a line-by-line process that creates a:
linear array.
detector array grid.
a series of sensitivity specks.
raster pattern.
DR and CR image receptors:
require a reader mechanism to capture the image signal.
have two classes: indirect and direct.
display a quantitative measure of receptor exposure.
work well with automatic exposure control.
A panel has a fill factor of 85%. What % is occupied by non-sensing electronics?
5%
10%
15%
25%
In CR, pixel pitch is dependent upon:
sampling frequency
laser energy wavelength of the reader
viewing monitor size
DEL size
Pixel bit depth determines:
image brightness
pixel dimension
gray shade levels
spatial resolution
In indirect DR detectors, the scintillator converts x-ray energy into:
a. electrical signal
b. electrons
c. light energy
d. gamma rays
A common feature between indirect and direct DR technology is:
Select the TRUE statement regarding computer radiography (CR):
Grids are of little value with CR
Fixed mode on Fuji systems requires precise positioning
CR imaging plates are very sensitive to post-exposure radiation.
CR plate sampling rates determine image brightness
Positioning an AP wrist projection off-center using CR may lead to:
preprocessing errors
incorrect histogram analysis
suboptimum image quality
all of the above
Underexposed radiographic images demonstrate:
increased contrast
decreased image brightness
visibility of grid lines
photon starvation
The purpose of a charge-coupled device (CCD) in DR is to:
convert x-ray energy into light
act as a photoconductor
collect light and convert it to electrons
both b and c
Fixed kVp exposure techniques require:
automatic exposure control (AEC)
an optimum threshold kVp
a minimum mA
radiographic grids
CR systems acquire clinical information by:
gathering light from a scintillator
direct digital transformation of x-rays to selenium
laser scanning a PSP plate
capturing light from a CCD
The final image appearance in terms of brightness and contrast is primarily due to:
data rescaling
the application of a look up table
total exposure to the detector
window and level controls
The relationship between detector “fill-factor” and spatial resolution is:
indirect
not a factor
indirect based on DEL depth
direct
According to the AAPM, a DI value of +4 indicates:
optimum exposure
underexposure
mid-range exposure
overexposure and an ALARA violation
A DR detector that is integral to the x-ray system means:
uses wireless tech
is built into the x-ray unit
is not hard-wired
must be used with generator interface
Which of the following factors would decrease remnant radiation exposure to a DR detector?
using an 8” air-gap
increasing kVp and keeping mAs the same
switching from an 8:1 grid to a 4:1 grid
increasing kVp from 75 to 87 and halving mAs
The total amount of clinically significant diagnostic image information is:
diagnostic acuity
image fidelity
diagnostic yield
diagnostic efficacy
