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