Mosby's Chapter 4 Digital Image Acquisition Practice Quiz
Bit depth is equal to: A. 2^n (n equals the number of bits) B. 4096 shades of gray C. Pixel pitch D. Bits times bytes
A. 2^n (n equals the number of bits)
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 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
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
Which of the following statements are accurate pertaining to the role of kVp in radiographic image production? (select 3) A. As kVp is increased, the 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 mA controls receptor exposure
A. As kVp is increased, the 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 decreases, receptor exposure remains constant because mA controls receptor exposure
Quality assurance and maintenance of CR cassettes include erasing plates at least: A. Daily B. Every 48 hours C. Every 3 months D. Weekly
A. Daily
Quantum noise limits ability to see: A. Detail B. Contrast C. Fatty tissue D. Additive pathologies
A. Detail
The thicker part of the anatomy should be placed under which aspect of the x-ray tube? A. Central ray B. Cathode C. Anode D. Collimator
B. Cathode
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
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
The useful image acquisition area of an image receptor is the: A. Detector element B. Detector size C. TFT size D. Dynamic range
B. Detector size
The relationship between kVp and receptor exposure may be described as: A. Directly proportional B. Direct, although not proportional C. Governed by the 15 to 50 rule D. Controlled by the x-ray tube current
B. Direct, although not proportional
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 is increased to compensate C. Grids reduce receptor exposure by only absorbing scatter radiation D. Receptor increases as grid ratio increases
B. Grids reduce receptor exposure unless mAs is increased to compensate
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. The level at which photoelectric interaction predominates
B. High
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
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
The active portion(s) of a CR IP is (are): A. ABC B. PSP C. DQE D. SNR
B. PSP
The smallest area represented in a digital image is the: A. Image matrix B. Pixel C. Voxel D. Bit
B. Pixel
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
As the amount of beam filtration is increases: 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 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
The range of SIDs that may be used with a focused grid is called: A. Grid ratio B. Objective plane C. Anticutoff distance D. Focal distance (grid radius)
D. Focal distance (grid radius)
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
In general, anything interfering with accurate image formation is known as: A. Underexposure B. Overexposure C. Motion D. Noise
D. Noise
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^2 D. Receptor exposure is reduced to one fourth
D. Receptor exposure is reduced to one fourth
Grid frequency is defined as: A. The same thing 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)
mAs directly controls: 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 produces at the anode D. The quantity of x-rays produced at the anode
D. The quantity of x-rays produced at the anode
The primary controlling factors of receptor exposure are: A. kVp and mAs B. mAs and SID C. SID and OID D. Sid, OID, FFS
A. kVp and mAs
Given an original technique of 30 mAs and 80 kVp, what 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
Mathematical codes used to generate the digital image are called: A. Binary codes B. Algorithms C. Binary digits D. Bytes
B. Algortithms
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 function of contrast is to: A. Make the image appear sharper B. Compensation for uneven anatomic structures C. Brighten the image D. Make details visible
D. Make details visible
What converts light into a charge? A. Diode B. Cathode C. AC to DC converter D. Photodiode
D. Photodiode
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 and quality of x-rays produced C. Focal-spot size, which controls the quantity and quality of x-rays produced D. kVp and bit depth
D. kVp and bit depth
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
Receptor exposure was formally called: A. Contrast B. Detail C. Density D. Distortion
C. Density
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
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
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
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
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
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
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
A grid with lead strips and aluminum interspacers that are angles 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
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
Undesirable fluctuations in brightness are called: A. MTF B. Image noise C. Quantization D. Scintillation
B. Image noise
Digital imaging is driven by: A. kVp B. mAs C. Image receptor D. Total exposure
D. Total exposure
Which of the following will result in higher spatial resolution? (select 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
Which of the following are true concerning grids? (select 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
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
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
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
Which of the following describe the outcome of using low kVp? (select 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
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
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
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 mAs^2 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
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 bay 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%
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
An indicator of the dose level needed to acquire an optimal image is: A. Detective quantum imaging B. Dose area product C. Field of view D. Dynamic range
B. Dose area product
Receptor exposure may be defined as: A. The 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 actual patient dose as measured by a meter embedded in the collimator is: A. Absorbed dose B. Dose area product C. Equivalent dose D. Doubling dose
B. Dose area product
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 factors result in poor spatial resolution? (select 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
Improper use of grids may result in an image artifact known as: A. SNR B. Moire pattern C. Elongation D. Foreshortening
B. Moire pattern
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
A radiographic image with few gray tones, primarily exhibiting black and white, would be described as having what time of contrast? (select 2) A. Long scale B. Short scale C. Low D. High
B. Short scale; D. High contrast
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
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
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
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
Which of the following describe the outcome of using high kVp? (select 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
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
Low signal-to-noise ratio results in what effect on the image? A. Higher quality B. No effect on quality C. Lower quality
C. Lower quality
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
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
The space from the center of one pixel to the center of an adjacent pixel is known as: A. Pixel density B. Bit depth C. Pixel pitch D. Matrix depth
C. Pixel pitch
Grid ratio is defined as: A. The ratio of 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
The number of electrons boiled off the cathode and consequently the number of x-rays produced are controlled by: A. kVp B. SID C. mA D. OID
C. mA
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
D. Weekly
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
Magnification is caused by: (select 2) A. Short SID B. Long SID C. Short OID D. Long OID
A. Short SID; D. Long OID
A software function that evens the brightness displayed in the image is called: A. Smoothing B. Equalization C. Postprocessing D. Subtraction
A. Smoothing
Gross overexposure of the IR results in: A. Saturation B. Oversampling C. Extreme latitude D. High spatial resolution
A. Saturation
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
The expression of image quality provided by a detector is called: A. MTF B. Matrix size C. SNR D. Nyquist frequency
A. MTF
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
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
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
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
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
The use of filtration: A. Greatly reduces receptor exposure because of the absorption of short-wavelength x-rays B. Greatly reduces radiographic receptor exposure exposure 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
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
Which of the following is a graphical representation of pixel values: A. Dynamic range B. Luminance C. Look-up table D. Histogram
D. Histogram
In digital radiography, inappropriate collimation causes: A. A fogged image B. Pixel unresponsiveness C. DICOM incompatibility D. Histogram analysis error
D. Histogram analysis error
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
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
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
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
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
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
