CHAPTER 4 Image Acquisition and Evaluation (Review)/K
Materials that make flat panel detectors possible are: a. Silicon dioxide b. Amorphous silicon c. Diodes d. Pixels
amorphous silicon
Quantum noise limits ability to see: a. Detail b. Contrast c. Fatty tissue d. Additive pathologies
detail
Quality assurance and maintenance of CR cassettes includes cleaning and inspecting the plates at least: a. Daily b. Every 48 hours c. Every 3 months d. Weekly
every 3 months
Quality assurance and maintenance of CR cassettes includes erasing plates at least: a. Daily b. Every 48 hours c. Every 3 months d. Weekly
every 48 hours
The radiographic image is formed by: a. Exit rays striking the image receptor b. Laser light c. Cosmic rays d. Electrons and heat
exit rays striking the image receptor
Digital imaging is driven by: a. kVp b. mAs c. JR speed class d. Exposure
exposure
The range of receptor exposures that provides a quality image is called: a. Detector latitude b. Exposure latitude c. Histogram d. Dynamic range
exposure latitude
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
focused grid
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
foreshortening
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
high-resolution monitor capable of displaying millions of pixels
The number of pixels/mm in an image is called: a. Pixel density b. Bit depth c. Pixel pitch d. Matrix depth
pixel density
Undesirable fluctuations in brightness are called: a. MTF b. Image noise c. Quantization d. Scintillation
scintillation
A software function that evens the brightness displayed in the image is called: a. Smoothing b. Equalization c. Postprocessing d. Subtraction
smoothing
Digital systems operate at what speed class? a. 200 b. 400 c. 100 d. The speed class chosen by the radiographer
speed class chosen by the radiographer
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)
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 produced at the anode d. The quantity of x-rays produced
the quantity of x-rays
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
the ratio of the height of the lead strips over the distance between the lead strips (h/d)
The 15% rule states that: a. Density maybe halved by decreasing kVp by 15% b. kVp should be 15% of the mAs selected c. Density may be halved by increasing kVp by 15% d. At least a 15% change in mAs is required to make a change visible
density maybe halved by decreasing kVp 15%
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
post-processing manipulation of the image
Elongation and foreshortening are examples of: a. Size distortion b. Shape distortion c. Motion d. Distortion caused by short SID and long OlD
shape distortion
Magnification is caused by: 1. Short SID 2. Long SID 3. Short OlD 4. Long OlD a. 2, 3 b. 1,4 c. 1, 3 d. l only
1,4
Exposure technique in digital imaging may be adjusted by: a. Lowering kVp b. Increasing mAs c. Shortening SID d. Increasing kVp
Increasing kVp
The expression of image quality provided by a detector is called: a. MTF b. Matrix size c. SNR d. Nyquist frequency
MTF (Modulation transfer function)
What converts light into a charge? a. Diode b. Cathode c. AC to DC converter d. Photodiode
Photodiode
The smallest resolvable area in a digital imaging device is: a. Detector size b. Detector element c. Matrix size d. Focal spot size
detector element
The relationship between kVp and density 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
direct although not proportional
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
increase contrast
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
increase mAs to compensate for number of rays removed from the primary rays
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
inside the exposure field, narrowing the histogram
Which of the following governs the relationship between SID and density? a. Reciprocity law b. 15% rule c. Inverse square law d. Ohm's law
inverse square law
Low kVp produces which of the following? 1. High contrast 2. Few gray tones 3. Long-scale contrast 4. Short-scale contrast S. Low contrast 6. Many gray tones a. 1, 2, 4 b. 3, 5, 6 c. 5 d. 1
1, 2, 4
Which of the following statements are true concerning the role of kVp in radiograph production? 1. As kVp is increased, penetrating ability of the x-rays increases 2. As kVp is increased, more x-rays exit the patient to strike the IR 3. As kVp is decreased, wavelength and density decrease 4. As kVp increases, radiographic density increases 5. As kVp decreases, radiographic density remains constant because mAs controls density a. 1, 2, 4 b. 1, 2, 3 c. 1, 3, 4 d. 5
1,2,4
Mathematical codes used to generate the digital image are called: a. Binary codes b. Algorithms c. Binary digits d. Bytes
algorithms
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
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
automatic rescaling
The smallest exposure change able to be captured by a detector is called: a. Spatial resolution b. Exposure latitude c. Pixel d. Contrast resolution
contrast resolution
Recorded detail 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
geometric representation of the part being radiographed
The use of filtration: a. Greatly reduces radiographic density because the absorption of short-wavelength x-rays b. Greatly reduces radiographic density because the absorption of high-energy x-rays c. Increases radiographic density by removing long-wavelength x-rays d. Has little effect on density because x-rays removed from beam are not image-producing rays
has little effect on density because x-rays removed from beam are not image producing x-rays
When AEC is used, increasing the kVp: a. Increases density proportionately b. Increases radiographic contrast c. Increases exposure time d. Has no effect on density
has no effect on density
More uniform penetration of anatomical 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
high
Use of technique charts: a. Is unnecessary for any examination 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
is helpful when manual techniques are used
The primary controlling factor(s) of contrast is(are): a. mAs, which controls 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 window width
kVp and window width
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
latitude of collimation that still allows the software to detect collimated edges
As speed class increases: a. The likelihood of noise increases b. The likelihood of noise decreases c. Patient exposure increases d. Sharpness increases
likelihood of noise increases
Smoothing software may result in: a. Enhanced fine detail b. Less distortion c. Loss of fine detail d. Increased distortion
loss of fine detail
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. OlD
mAs
The primary controlling factors of density are: a. kVp and SID b. mAs and window level c. SID and OlD d. OlD and FSS
mAs and window level
The number of pixels making up the digital image is the: a. Pixel depth b. Matrix size c. Pixel pitch d. Field of view
matrix size
Which of the following statements concerning grids are true? 1. Contrast improvement factor is the measure of the ability of a grid to enhance contrast 2. Grid selectivity is the ratio of primary radiation transmitted through the grid to secondary radiation transmitted through the grid 3. Grids are used when part thickness is less than 10 cm 4. GCF is the amount of increase in kVp necessary when converting from nongrid to grid technique S. The primary purpose of grids is radiation protection 6. The main function of grids is to prevent Compton scatter from reaching the film 7. Grids prevent the production of scatter a. 1, 2, 6 b. 1, 2, 4, 6 c. 1, 2, 3, 5, 7 d. 1, 2, 6, 7
1,2,6
Better recorded detail may be caused by which of the following factors? 1. Long SID 2. Long OlD 3. Short SID 4. Short OlD 5. Large focal spot 6. Small focal spot a. 2, 3, 5 b. 1, 4, 6 c. 1, 4, 5, 6 d. 2, 3, 6
1,4,6
A radiograph 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.l and 4 d. 2
2 & 4
Poorer recorded detail may be caused by which of the following factors? 1. Long SID 2. Long OlD 3. Large focal spot 4. Small focal spot 5. Patient motion 6. Magnification a. 2, 3, 5, 6 b. 2, 3 c. 1, 4, 6 d. 5, 6
2, 3, 5, 6
The available gray scale of an imaging system is determined by: a. Pixel pitch b. Bit depth c. Exposure latitude d. Image latitude
bit depth
The best scatter cleanup is achieved with the use of: a. Air gap technique b. Focused grids c. Crosshatch grids d. Parallel grids
crosshatch grids
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
2n (n equals number of bits)
High kVp produces which of the following? 1. High contrast 2. Few gray tones 3. Long-scale contrast 4. Short-scale contrast S. Low contrast 6. Many gray tones a. 1,2,4 b. 3, 5, 6 c. 5 d. 1
3, 5, 6
Given an original technique of 30 mAs and 80 kVp, which of the following would produce a radiograph with double the density? a. 60 mAs, 90 kVp b. 30 mAs, 92 kVp c. 15 mAs, 80 kVp d. 30 mAs, 70 kVp
30 mAs, 92 kVp
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 maintain the same density as the original film? a. 50 mAs b. 2mAs c. 40 mAs d. 120 mAs
50 mAs
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
DAP - dose area product
Inappropriate collimation causes: a. A fogged image b. Pixel unresponsiveness c. DICOM incompatibility d. Histogram analysis error
Histogram analysis error
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
Nyquist frequency
The active portion of a CR IP is(are): a. Calcium tungstate b. PSP c. Silver bromide crystals d. Rare earth phosphor
PSP - Photostimulable phosphor
Differential absorption of the x-ray beam is a function of: a. Compton interaction b. Atomic mass of anatomical structures c. mAs d. Photoelectric interaction
Photoelectic interaction
The smallest area represented in a digital image is the: a. Image matrix b. Pixel c. Voxel d. Bit
Pixel
The law stating that any combinations of mA and time that produce the same mAs value will produce the same radiographic density is the: a. Inverse square law b. mAs-density law c. Reciprocity law d. 15% law
Reciprocity law
Digital imaging is more sensitive to: a. Scatter and background radiation b. Fluorescent lights c. Free electrons d. Free radicals
Scatter and background radiation
Which of the following affects radiographic density? a. Atomic mass of the x-ray tube anode b. X-ray tube angle c. Atomic number of the cathode filament
X-ray tube angle
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
cathode
Differences in densities on a radiograph describe: a. Density b. Recorded detail c. Log relative exposure d. Contrast
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
contrast decreases
Density may be defined as: a. Darkness on a radiographic image b. A combination of contrast and recorded detail c. The light areas of a radiographic image d. Differences in dark areas on a radiographic image
darkness on a radiographic image
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
decreased density on a radiograph as a result of absorption of image-forming rays
Excessive processing of the digital image may: a. Degrade visibility of anatomy b. Provide additional anatomical information c. Enhance visibility of desired anatomy d. Increase patient dose
degrade visibility of anatomy
As beam restriction increases (becomes tighter): a. Density increases b. Density increases as a result of focusing of x-rays c. Density decreases d. Density is not affected
density decreases
Which of the following describes the relationship between mAs and density? a. Density is directly proportional to mAs b. Density is inversely proportional to mAs c. Density is directly proportional to mAs2 d. mAs controls the number of electrons boiled off the anode and the number of x-rays produced
density is proportional to mAs
If SID is doubled, what may be said about radio graphic density? a. Density doubles b. Density is reduced by one-half c. Density is reduced by new mAs2 d. Density is reduced to one-fourth
density is reduced to 1/4
The useful image acquisition area of an image receptor is: a. Detector element b. Detector size c. TFT size d. Dynamic range
detector size
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
dose area product
What allows more anatomical structures to be captured during an exposure? a. Contrast resolution b. Spatial resolution c. Dynamic range d. MTF
dynamic range
An artificial increase in display contrast at an edge of the image is: a. Smoothing b. Edge enhancement c. Contrast resolution d. Spatial resolution
edge enhancement
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
elongation
Which of the following describes the relationship between radiographic density and the use of grids? a. Grids always reduce density b. Grids reduce density unless mAs is increased to compensate c. Grids reduce density by absorbing scatter radiation d. Density increases as grid ratio increases
grids reduce density unless mAs is increased to compensate
A high SNR provides an image with: a. Poor spatial resolution b. Higher spatial resolution c. Poor contrast d. Higher distortion
higher spatial resolution
Which of the following is a graphical representation of pixel values? a. Dynamic range b. Luminance c. Look-up table d. Histogram
histogram
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
image appearance consistency
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
increased contrast because of reduction in the number of Compton interactions that occur
The function of contrast is to: a. Make the image appear sharper b. Compensate for uneven anatomical structures c. Brighten the image d. Make detail visible
make detail visible
Distortion may be described as: a. Misrepresentation of an anatomical structure on film b. Foreshortening c. Elongation d. Magnification
misrepresentation of an anatomical structure on film
Optimal recorded detail may be created using which of the following factors? a. Large focal spot b. Narrow pixel pitch c. Long OlD d. Short SID
narrow pixel pitch
The appearance of 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
not as good as on radiologists monitors
As speed class decreases: a. The likelihood of noise increases b. Noise is unaffected c. Patient exposure increases d. Sharpness decreases
patient exposure decreases
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
pixel pitch
Poorer recorded detail may be caused by which of the following factors? a. Short OlD b. Long SID c. Small focal spot d. Pixel pitch wide
pixel pitch wide
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
quantization
The range of SIDs that may be used with a focused grid is called: a. Grid ratio b. Objective plane c. Anticutoff distances d. Grid radius
radius
If SID is reduced by one-half, what must be done to mAs to maintain a constant density? 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
reduce mAs to 1/4 its original value
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
scintillator
The portion of contrast that is caused by variations in the anatomy or is secondary to pathological changes is called: a. Radiographic contrast b. Anatomical contrast c. Pathological contrast d. Subject contrast
subject contrast
TFT is a: a. Thin film transistor—a diode used in rectifiers b. Thin film transistor—an electronic device used in CR cassettes c. Thin film transistor—an electronic switch used on flat panel detectors d. Thin film transistor—the electronics used with AECs
thin film transistor - an electronic switch used on flat panel detectors
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 OlD d. Works because scatter radiation travels in divergent paths and misses the IR as a result of increased OlD
works because scatter radiation travels in divergent paths and misses the IR as a result of increased OID