Receptor exposure may be defined as:
a. Amount of remnant radiation striking the image receptor
b. Dose area product
c. DQE
d. Differences in dark areas on a radiographic image
B. Dose area product
The radiographic image is formed by:
a. Exit rays striking the image receptor
b. Laser light
c. Cosmic rays
d. Electrons and heat
A. Exit rays striking the image receptor
The primary controlling factors of receptor exposure are:
a. kVp and mAs
b. mAs and SID
c. SID and OID
d. SID, OID, FSS
B. mAs and SID
-mAs controls the electrons flowing through the x-ray tube and striking the anode.Therefore it directly controls the number of x-rays produced. In digital imaging, brightness may be manipulated using window level.
Which of the following describes the relationship between mAs and receptor exposure?
a. Receptor exposure is directly proportional to mAs
b. Receptor exposure is inversely proportional to mAs
c. Receptor exposure is directly proportional to mAs2
d. mAs controls the number of electrons boiled off the anode and the number of x-rays produced
A. Receptor exposure is directly proportional to mAs
-Whatever is changed in mAs directly impacts receptor exposure.
The number of electrons boiled off the cathode and consequently the number of x-rays produced are controlled by:
a. kVp
b. SID
c. mAs
d. OID
C. mAs
-mAs controls the electrons flowing through the x-ray tube and striking the anode. Therefore it directly controls the number of x-rays produced.
Receptor exposure was formerly called:
a. Contrast
b. Detail
c. Density
d. Distortion
C. Density
The active portion(s) of a CR IP is (are):
a. ABC
b. PSP
c. DQE
d. SNR
B. PSP
-Photostimulable phosphor.
mAs directly control:
a. The energy of the x-ray emission spectrum
b. The quality and quantity of x-rays produced at the cathode
c. The quality and quantity of x-rays produced at the anode
d. The quantity of x-rays produced at the anode
D. The quantity of x-rays produced at the anode
-mAs is a quantitative factor.
Visible differences in adjacent structures on a radiographic image describe:
a. Receptor exposure
b. Spatial resolution
c. Signal loss
d. Contrast resolution
D. Contrast resolution
The primary controlling factor(s) of contrast is (are):
a. mAs, which control the energy of the x-rays produced
b. kVp, which primarily controls the quantity of x-rays produced at the target
c. Focal-spot size, which controls the quantity and quality of x-rays produced
d. kVp and bit depth
D. kVp and bit depth
-kVp controls the wavelength and penetrating ability of the beam. In digital imaging window width can be used to manipulate contrast.
The relationship between kVp and receptor exposure may be described as:
a. Directly proportional
b. Direct, although not proportional
c. Governed by the 15-50 rule
d. Controlled by x-ray tube current
B. Direct, although not proportional
-It is governed by the 15% rule.
The 15% rule states that:
a. Receptor exposure may be halved by decreasing kVp by 15%
b. kVp should be 15% of the mAs selected
c. Receptor exposure may be halved by increasing kVp by 15%
d. At least a 15% change in mAs is required to make a change visible
A. Receptor exposure may be halved by decreasing kVp by 15%
Choose all of the following statements that are accurate pertaining to the role of kVp in radiographic image production (choose 3):
a. As kVp is increased, penetrating ability of the x-rays increases
b. As kVp is increased, more x-rays exit the patient to strike the image receptor
c. As kVp is decreased, wavelength decreases
d. As kVp increases, receptor exposure increases
e. As kVp decreases, receptor exposure remains constant because mAs controls receptor exposure
A. As kVp is increased, penetrating ability of the x-rays increases
B. As kVp is increased, more x-rays exit the patient to strike the image receptor
D. As kVp increases, receptor exposure increases
-Think about each answer individually before answering this question.
Given an original technique of 30 mAs and 80 kVp, which of the following would produce an image with double the receptor exposure?
a. 60 mAs, 90 kVp
b. 30 mAs, 92 kVp
c. 15 mAs, 80 kVp
d. 30 mAs, 70 kVp
B. 30 mAs, 92 kVp
-The use of the 15% rule to increase kVp results in double the density. In equal receptor exposure as doubling mAs.
Which of the following governs the relationship between SID and receptor exposure?
a. Reciprocity law
b. 15% rule
c. Inverse square law
d. Ohm’s law
C. Inverse square law
If SID is doubled, what may be said about receptor exposure?
a. Receptor exposure doubles
b. Receptor exposure is reduced by one half
c. Receptor exposure is reduced by new mAs
d. Receptor exposure is reduced to one fourth
D. Receptor exposure is reduced to one fourth
-This is another way of asking about the inverse square law.
If SID is reduced by one half, what must be done to mAs to maintain a constant receptor exposure?
a. Reduce mAs to one fourth its original value
b. Reduce mAs to one half its original value
c. Increase mAs by four times its original value
d. Increase mAs by two times its original value
A. Reduce mAs to one fourth its original value
Choose all factors below that result in poor spatial resolution (choose 4):
a. Long SID
b. Long OID
c. Large focal spot
d. Small focal spot
e. Patient motion
f. Magnification
B. Long OID
C. Large focal spot
E. Patient motion
F. Magnification
-These factors all impact the geometry of the image.
In digital fluoroscopy, what equipment should be used to view the image?
a. Conventional view box
b. High-resolution monitor capable of displaying millions of pixels
c. High-definition television
d. Plasma television required
B. High-resolution monitor capable of displaying millions of pixels
-The monitor must be high resolution.
A primary advantage to digital fluoroscopy is:
a. Postprocessing manipulation of the image
b. Radiation dose to the patient is substantially lower
c. No radiologist is needed
d. Lower cost
A. Postprocessing manipulation of the image
Which of the following describes the relationship between receptor exposure and the use of grids?
a. Grids always reduce receptor exposure
b. Grids reduce receptor exposure unless mAs are increased to compensate
c. Grids reduce receptor exposure by only absorbing scatter radiation
d. Receptor exposure increases as grid ratio increases
B. Grids reduce receptor exposure unless mAs are increased to compensate
The use of filtration:
a. Greatly reduces receptor exposure because of the absorption of short-wavelength x-rays
b. Greatly reduces radiographic receptor exposure because of the absorption of high-energy x-rays
c. Increases radiographic receptor exposure by removing long-wavelength x-rays
d. Has little effect on receptor exposure because x-rays removed from beam are not image-producing rays
D. Has little effect on receptor exposure because x-rays removed from beam are not image-producing rays
-Overall, the beam is harder so contrast may be lower.
As beam restriction increases (becomes tighter):
a. Receptor exposure increases
b. Receptor exposure increases as a result of focusing of x-rays
c. Receptor exposure decreases
d. Receptor exposure is not affected
C. Receptor exposure decreases
Which of the following affects receptor exposure?
a. Atomic mass of the x-ray tube anode
b. X-ray tube angle
c. Atomic number of the cathode filament
B. X-ray tube angle
-Due to a change in SID resulting from the tube angle
The variation of x-ray intensity along the longitudinal axis of the x-ray beam describes:
a. Beam collimation
b. Positive beam limitation
c. Anode heel effect
d. X-ray emission spectrum
C. Anode heel effect
-The intensity of the x-ray beam is actually a little higher toward the cathode side of the tube.
The thicker part of anatomy should be placed under which aspect of the x-ray tube?
a. Central ray
b. Cathode
c. Anode
d. Collimator
B. Cathode
-Anode heel effect
The function of contrast is to:
a. Make the image appear sharper
b. Compensate for uneven anatomic structures
c. Brighten the image
d. Make detail visible
D. Make detail visible
-Without contrast, produced by differential absorption of the x-ray beam, detail cannot be visible.
A radiographic image with few gray tones, primarily exhibiting black and white, would be described as having what type of contrast?
1. Long scale
2. Short scale
3. Low
4. High
a. 2 and 4
b. 1 and 3
c. 1 and 4
d. 2
A. 2 and 4
Lower spatial resolution may be caused by which of the following factors?
a. Short OID
b. Long SID
c. Small focal spot
d. Wide pixel pitch
D. Wide pixel pitch
-This is the space from center to center of adjacent pixels.
Choose all that describe the outcome of using high kVp (choose 3):
a. High contrast
b. Few gray tones
c. Long-scale contrast
d. Short-scale contrast
e. Low contrast
f. Many gray tones
C. Long-scale contrast
E. Low contrast
F. Many gray tones
Choose all that describe the outcome of using low kVp (choose 3):
a. High contrast
b. Few gray tones
c. Long-scale contrast
d. Short-scale contrast
e. Low contrast
f. Many gray tones
A. High contrast
B. Few gray tones
D. Short-scale contrast
More uniform penetration of anatomic structures occurs when what level of kVp is used?
a. Low
b. High
c. kVp does not affect penetration
d. Level at which photoelectric interaction predominates
B. High
Differential absorption of the x-ray beam is a function of:
a. Compton interaction
b. Atomic mass of anatomic structures
c. mAs
d. Photoelectric interaction
D. Photoelectric interaction
-Photoelectric interaction results in absorption of incoming photons. It is also very influenced by the atomic number, not atomic mass, of anatomic structures
What effect does beam restriction have on contrast?
a. Decreases contrast by focusing the x-ray beam
b. Decreases contrast because of higher kVp level used
c. Increases contrast by focusing the x-ray beam
d. Increases contrast because of reduction in the number of Compton interactions that occur
D. Increases contrast because of reduction in the number of Compton interactions that occur
-Compton interactions produce scatter, which causes contrast to decrease.
The adjustment in technical factors required when using beam restriction is:
a. Increase kVp
b. Decrease kVp to reduce the number of Compton interactions taking place
c. Decrease mAs to reduce the number of Compton interactions taking place
d. Increase mAs to compensate for the number of rays removed from the primary beam
D. Increase mAs to compensate for the number of rays removed from the primary beam
-Rays that have been removed from the beam must be restored by increasing mAs. The area being irradiated still remains smaller.
What effect does the use of radiographic grids have on contrast?
a. Decreases contrast
b. Increases contrast
c. No effect on contrast
d. Increases contrast by absorbing scatter radiation
D. Increases contrast by absorbing scatter radiation
-Many of the scatter photons are being absorbed by the grid, resulting in higher contrast.
As the amount of beam filtration is increased:
a. Contrast increases
b. There is no effect on contrast
c. Contrast decreases
d. Contrast increases because the beam is harder
C. Contrast decreases
-The overall wavelength of the beam is shorter, resulting in lower contrast.
The portion of contrast that is caused by variations in the anatomy or that is secondary to pathologic changes is called:
a. Radiographic contrast
b. Anatomic contrast
c. Pathologic contrast
d. Subject contrast
D. Subject contrast
Spatial resolution is:
a. Photographic representation of the part being radiographed
b. Controlled by kVp
c. Controlled by mAs
d. Geometric representation of the part being radiographed
D. Geometric representation of the part being radiographed
-Controlled by SID, OID, focal-spot size, pixel pitch 40
Choose all that will result in higher spatial resolution (choose 3):
a. Long SID
b. Long OID
c. Short SID
d. Short OID
e. Large focal spot
f. Small focal spot
A. Long SID
D. Short OID
F. Small focal spot
Optimal spatial resolution may be created using which of the following factors?
a. Large focal spot
b. Narrow pixel pitch
c. Long OID
d. Short SID
B. Narrow pixel pitch
-Pixel pitch is very important to detail in digital imaging.
Improper use of grids may result in an image artifact known as:
a. SNR
b. Moiré pattern
c. Elongation
d. Foreshortening
B. Moiré pattern
Distortion may be described as:
a. Misrepresentation of an anatomic structure on the image
b. Foreshortening
c. Elongation
d. Magnification
A. Misrepresentation of an anatomic structure on the image
-Choices B, C, and D are all examples of distortion.
Elongation and foreshortening are examples of:
a. Size distortion
b. Shape distortion
c. Motion
d. Distortion caused by short SID and long OID
B. Shape distortion
Magnification is caused by:
1. Short SID
2. Long SID
3. Short OID
4. Long OID
a. 2, 3
b. 1, 4
c. 1, 3
d. 1 only
B. 1, 4
-The optimum conditions are longer SID and shorter OID.
Distortion that occurs when the x-ray beam is angled against the long axis of a part is:
a. Elongation
b. Magnification
c. Minification
d. Foreshortening
D. Foreshortening
-This results in the part appearing shorter than it really is.
Distortion that occurs when the x-ray beam is angled along the long axis of a part is:
a. Elongation
b. Magnification
c. Minification
d. Misrepresentation
A. Elongation
-This results in the part appearing longer than it really is.
The actual patient dose as measured by a meter embedded in the collimator is:
a. RAD—radiation absorbed dose
b. DAP—dose area product
c. REM—radiation equivalent man
d. Doubling dose
B. DAP—dose area product
-Digital imaging takes into account the total dose to the patient.
Quality assurance and maintenance of CR cassettes include cleaning and inspecting the plates at least:
a. Daily
b. Every 48 hours
c. Every 3 months
d. Weekly
C. Every 3 months
Quality assurance and maintenance of CR cassettes include erasing plates at least:
a. Daily
b. Every 48 hours
c. Every 3 months
d. Weekly
B. Every 48 hours
-But erasing daily is better and preferred.
Quality assurance of digital imaging requires the uniformity of processing codes to ensure:
a. Image appearance consistency
b. Faster throughput
c. Less heat loading on the anode
d. Smoother integration into PACS
A. Image appearance consistency
A software function that evens the brightness displayed in the image is called:
a. Smoothing
b. Equalization
c. Postprocessing
d. Subtraction
A. Smoothing
-However, smoothing may negatively impact resolution.
Beam-part-receptor alignment latitude describes:
a. The latitude of collimation that still allows the software to detect collimated edges
b. The alignment that maintains ALARA requirements
c. Exposure latitude
d. Acceptable distortion of the image
A. The latitude of collimation that still allows the software to detect collimated edges
-Detection of collimated edges is crucial to obtaining an accurate histogram.
To reduce patient dose, exposure technique in digital imaging should be adjusted by:
a. Lowering kVp
b. Increasing mAs
c. Shortening SID
d. Increasing kVp
D. Increasing kVp
-This is in congruence with ALARA.
Digital image receptors are more sensitive to:
a. Scatter and background radiation
b. Fluorescent lights
c. Free electrons
d. Free radicals
A. Scatter and background radiation
In digital radiography inappropriate collimation causes:
a. A fogged image
b. Pixel unresponsiveness
c. DICOM incompatibility
d. Histogram analysis error 57.
D. Histogram analysis error 57.
The appearance of digital images on technologists’ monitors is:
a. The same as on radiologists’ monitors
b. Substantially better than on radiologists’ monitors
c. Not as good as on radiologists’ monitors
C. Not as good as on radiologists’ monitors
-Technologists’ monitors are not usually high definition (HD).
Digital imaging is driven by:
a. kVp
b. mAs
c. IR speed class
d. Exposure
D. Exposure
-Total exposure reaching the IR
Digital systems operate at what speed class?
a. 200
b. 400
c. 100
d. The speed class chosen by the radiographer
D. The speed class chosen by the radiographer
An artificial increase in display contrast at an edge of the image is:
a. Smoothing
b. Edge enhancement
c. Contrast resolution
d. Spatial resolution
B. Edge enhancement
-This enhances visibility of detail.
As speed class increases:
a. The likelihood of noise increases
b. The likelihood of noise decreases
c. Patient exposure increases
d. Sharpness increases
A. The likelihood of noise increases
-This may allow for higher kVp and lower mAs, which causes an increase in quantum mottle or noise.
As speed class decreases:
a. The likelihood of noise increases
b. Noise is unaffected
c. Patient exposure increases
d. Sharpness decreases
C. Patient exposure increases
-More total exposure is required to produce a useable image.
Smoothing software may result in:
a. Enhanced fine detail
b. Less distortion
c. Loss of fine detail
d. Increased distortion
C. Loss of fine detail
Excessive processing of the digital image may:
a. Degrade visibility of anatomy
b. Provide additional anatomic information
c. Enhance visibility of desired anatomy
d. Increase patient dose
A. Degrade visibility of anatomy
-The more the image is processed the greater the opportunity for image degradation.
A high SNR provides an image with:
a. Poor spatial resolution
b. Higher spatial resolution
c. Poor contrast
d. Higher distortion
B. Higher spatial resolution
-There is a greater difference between the signal and any noise that may be present.
Quantum noise limits ability to see:
a. Detail
b. Contrast
c. Fatty tissue
d. Additive pathologies
A. Detail
If the exposure field is not accurately recognized, the histogram will contain data:
a. Outside the exposure field, narrowing the histogram
b. Inside the exposure field, widening the histogram
c. Outside the exposure field, widening the histogram
d. Inside the exposure field, narrowing the histogram
C. Outside the exposure field, widening the histogram
Grid ratio is defined as:
a. The ratio of the lead strips to the space between them
b. The thickness of the lead strips divided by the thickness of the aluminum interspacers
c. The ratio of the height of the lead strips over the distance between the lead strips
d. The ratio of the distance between the lead strips over the height of the lead strips
C. The ratio of the height of the lead strips over the distance between the lead strips
-Expressed as H/D. Did you notice how choice B tried to get your attention? Be sure to read the entire answer.
Grid frequency is defined as:
a. The same as grid ratio
b. The amount of lead in the grid (expressed in terms of focusing distance)
c. How often a grid is used
d. The amount of lead in the grid (expressed as the number of lead strips per inch)
D. The amount of lead in the grid (expressed as the number of lead strips per inch)
Choose all that are true concerning grids (choose 3):
a. Contrast improvement factor is the measure of the ability of a grid to enhance contrast
b. Grid selectivity is the ratio of primary radiation transmitted through the grid to secondary radiation transmitted through the grid
c. Grids are used when part thickness is less than 10 cm
d. GCF is the amount of increase in kVp necessary when converting from nongrid to grid technique
e. The primary purpose of grids is radiation protection
f. The main function of grids is to prevent Compton scatter from reaching the IR
g. Grids prevent the production of scatter
A. Contrast improvement factor is the measure of the ability of a grid to enhance contrast
B. Grid selectivity is the ratio of primary radiation transmitted through the grid to secondary radiation transmitted through the grid
F. The main function of grids is to prevent Compton scatter from reaching the IR
-Keep in mind that grids are used over part thickness of 10 cm; the grid conversion factors are used to change mAs, not kVp; and grids do not prevent the production of scatter, they just try to absorb it after it has been produced.
A grid with lead strips and aluminum interspacers that are angled to coincide with the divergence of the x-ray beam is called a:
a. Parallel grid
b. Focused grid
c. Crosshatch grid
d. Rhombic grid
B. Focused grid
-These grids can be used only within a certain range of SIDs, as stated on the label on the grid.
The range of SIDs that may be used with a focused grid is called:
a. Grid ratio
b. Objective plane
c. Anti cut off distances
d. Grid radius
D. Grid radius
-Using a focused grid outside of its grid radius will result in grid cutoff.
The best scatter cleanup is achieved with the use of:
a. Air gap technique
b. Focused grids
c. Crosshatch grids
d. Parallel grids
C. Crosshatch grids
-But crosshatch grids prevent angling of the tube and are extremely susceptible to grid cutoff.
Grid cutoff may be described as:
a. Decreased density in the middle of the radiograph caused by the use of a parallel grid inserted upside down
b. Decreased density on a radiograph as a result of absorption of image-forming rays
c. Increased density in the center of a radiograph caused by the use of a focused grid inserted upside down
d. Decreased density on the edges of a radiograph only
B. Decreased density on a radiograph as a result of absorption of image-forming rays
-Choice A is incorrect because decreased density in the middle would not be caused by use of an inverted parallel grid. Choice C is incorrect because density would decrease in the middle of this radiograph. Choice D is incorrect because density could decrease across the entire radiograph, depending on how the grid has been positioned.
When a nongrid technique using 10 mAs and 75 kVp is changed to a 12:1 grid using 75 kVp, what new mAs must be used to create the same image?
a. 50 mAs
b. 2 mAs
c. 40 mAs
d. 120 mAs
A. 50 mAs
-The grid conversion factor or Bucky factor for a 12:1 grid is 5 times the original mAs.
Use of the air gap technique:
a. Works because x-rays are absorbed in the air between the patient and the film
b. Should occur when possible
c. May cause some magnification because of decreased OID
d. Works because scatter radiation travels in divergent paths and misses the IR as a result of increased OID
D. Works because scatter radiation travels in divergent paths and misses the IR as a result of increased OID
-Even though not used much anymore, it is particularly effective on lateral cervical spine radiographs.
Use of technique charts:
a. Is unnecessary for any exam because of AECs
b. Does not require that the part thickness be measured with calipers
c. Is usually based on fixed mAs and variable kVp
d. Is helpful when manual techniques are used
D. Is helpful when manual techniques are used
-Technique charts are generally not needed for exams when AECs are used
When AEC is used, increasing the kVp:
a. increases the exposure time
b. increases the image contrast
c. decreases the exposure time
d. has no effect on image quality
D. has no effect on image quality
-Automatic exposure controls are set to terminate the exposure after a certain amount of radiation has passed through the ionization chamber. Consequently, changes in kVp will have no effect on receptor exposure. Some effect on contrast may occur if the change in kVp is substantial. The following answers relate to terminology used in digital imaging. Be certain to review these basic concepts. Keep in mind the ARRT exam will not ask questions related to specific brands of equipment made by various manufacturers. Therefore, the concepts tested should be broad in nature, similar to these questions.
The CR reader unit scans the IP with a(n):
a. Infrared light
b. Laser
c. Sonar
d. Visible white light
B. Laser
Which of the following maintains image brightness over a wide range of exposures?
a. AEC
b. Bit depth
c. Automatic rescaling
d. Detector size
C. Automatic rescaling
The available gray scale of an imaging system is determined by:
a. Pixel pitch
b. Bit depth
c. Exposure latitude
d. Image latitude
B. Bit depth
The smallest exposure change able to be captured by a detector is called:
a. Spatial resolution
b. Exposure latitude
c. Pixel
d. Contrast resolution
D. Contrast resolution
An indicator of the dose level needed to acquire an optimal image is:
a. Detective quantum efficiency
b. Dose area product
c. Field of view
d. Dynamic range
B. Dose area product
The useful image acquisition area of an image receptor is:
a. Detector element
b. Detector size
c. TFT size
d. Dynamic range
B. Detector size
The smallest resolvable area in a digital imaging device is:
a. Detector size
b. Detector element
c. Matrix size
d. Focal-spot size
B. Detector element
What allows more anatomic structures to be captured during an exposure?
a. Contrast resolution
b. Spatial resolution
c. Dynamic range
d. MTF
C. Dynamic range
The range of receptor exposures that provides a quality image is called:
a. Detector latitude
b. Exposure latitude
c. Histogram
d. Dynamic range
B. Exposure latitude
Which of the following is a graphical representation of pixel values?
a. Dynamic range
b. Luminance
c. Look-up table
d. Histogram
D. Histogram
Undesirable fluctuations in brightness are called:
a. MTF
b. Image noise
c. Quantization
d. Scintillation
B. Image noise
The number of pixels making up the digital image is the:
a. Pixel depth
b. Matrix size
c. Pixel pitch
d. Field of view
B. Matrix size
The expression of image quality provided by a detector is called:
a. MTF
b. Matrix size
c. SNR
d. Nyquist frequency
A. MTF
-Modulation transfer function
Which of the following terms describes the highest spatial frequency that can be recorded by a digital detector?
a. Spatial resolution
b. Contrast resolution
c. MTF
d. Nyquist frequency
D. Nyquist frequency
What converts light into a charge?
a. Diode
b. Cathode
c. AC to DC converter
d. Photodiode
D. Photodiode
The smallest area represented in a digital image is the:
a. Image matrix
b. Pixel
c. Voxel
d. Bit
B. Pixel
-Picture element
The number of pixels/mm in an image is called:
a. Pixel density
b. Bit depth
c. Pixel pitch
d. Matrix depth
A. Pixel density
The space from the center of a pixel to the center of the adjacent pixel is called:
a. Pixel density
b. Bit depth
c. Pixel pitch
d. Matrix depth
C. Pixel pitch
Mathematical codes used to generate the digital image are called:
a. Binary codes
b. Algorithms
c. Binary digits
d. Bytes
A. Algorithms
The process of assigning a value to each pixel to represent a gray tone is called:
a. Quantization
b. Scintillating
c. Nyquist frequency
d. Sampling
A. Quantization
A material that absorbs x-ray energy and emits part of that energy as visible light is called:
a. Diode
b. Scintillator
c. TFT
d. Cathode
B. Scintillator
Bit depth is equal to:
a. 2n (n equals the number of bits)
b. 4096 shades of gray
c. Pixel pitch
d. Bits times bytes
A. 2n (n equals the number of bits)