Chapter 19-Digital Imaging
matrix size
1,024 X 1,024 is a measure of this quantity.
c
A digital image containing a discrete number of rows and columns of picture elements is called: a) detection array b) display table c) matrix d) pixel
b
A digital image is made up of a: a) pixel of matrices b) matrix of pixels c) vortex of pixels d) matrix of vortices
b
A digital image is made up of: a) a pixel of matrices b) a matrix of pixels c) a vortex of pixels d) a matrix of vortices
b
A discrete number of rows and columns in a square are knows as: a) pixel b) matrix c) LUT d) algorithm
matrix
A group of numbers arranged in rows and columns.
a
A line pair is a line in the image and the space next to it(its corresponding interspace) a) true b) false
b
A matrix size with a smaller number of pixels will result in an image that is: a) higher contrast b) lower in image detail resulting in an unclear image c) resolved with more sharpness d) darker
spatial frequency
A measure of resolution; usually expressed in line pairs per millimeter(lp/mm).
pixel
A picture element of a matrix that contains information on its location and intensity.
c
A pixel with a bit depth of 11 can display _ shades of gray a) 512 b) 1024 c) 2048 d) 4095
a
A principle advantage of digital imaging over film/screen is the ability to post-press the image appearance: a) true b) false
window level
Adjusting _ up or down changes the density(brightness) of a digital image.
brightness
Amount of luminance an image displays on a monitor
a
Any unwanted information on an image is the definition for: a) artifacts b) penumbra c) image fog d) pixel loss
artifact
Any unwanted optical density on a radiography or other film-type image receptor.
matrix
Array of cells arranged in columns and rows
c
As the amount of noise decreases in the image, the contrast resolution _ and the spatial resolution _ a) increases, decreases b) decreases, is not affected c) increases, is not affected d) decreases, increases
c
As the number of XR photons reaching the detectors increases, the signal produced _ and the subsequent image noise _ a) increases. increases b) decreases, decreases c) increases, decreases d) decreases, increases
c
As the window width (WW) increases, the number of different intensities(shades of gray) in the image _ and therefore the image contrast _ a) increases, increases b) decreases, decreases c) increases, decreases d) decreases, increases
c
Calculate the spatial frequency of an imagine system is the pixel size is 0.15 mm a) 0.30 lp/mm b) 1.51 lp/mm c) 3.33 lp/mm d) 6.67 lp/mm
bitdepth
Calculated using the formula 2^n, reports the number of gray shades available
quantum noise
Caused by too few photons reaching the image receptor to form the image; resulting in muted or grainy appearance.
a
Changes in FOV and matrix size will not affect each other, but a change in either one will affect pixel size: a) true b) false
b
Contrast Resolution describes: a) the maximum separation of two objects that can be distinguished as separate objects b) the minimum density difference b/t two tissues that can distinguish separate tissues c) the maximum density difference b/t two tissues that can be distinguished as separate d) the minimum separation of two objects that can be distinguished as separate objects
b
Contrast resolution can be described as the: a) MAXIMUM density or intensity difference of two objects that can be distinguished as separate in the image b) MINIMUM density or intensity difference of two objects that can be distinguished as separate in the image
b
Contrast resolution describes: a) the maximum separation of two objects that can be distinguished as separate objects on the image b) the minimum density difference between two tissues that can distinguish separate tissues c) the maximum density difference between two tissues that can be distinguished as separate tissues d) the minimum separation of two objects that can be distinguished as separate objects on the image
a
Contrast resolution increases as pixel size _ a) increases b) decreases c) stays the same
FOV
Describes how much of the patient is imaged in a digital image matrix.
b
Digital imaging exhibits _ compared to film screen imagine a) greater luminance b) wider exposure latitude c) lower contrast resolution d) superior detail
a
Digital imaging has _ compared with film/screen: a) wider exposure latitude b) more narrow exposure latitude c) more dose d) more error
pixel
Each cell in a matrix; short for "picture element"
c
For a given FOV, spatial resolution will be _ for a _ matrix size: a) lower, larger b) higher, smaller c) lower, smaller
spatial frequency
Formula to calculate this is 1/2(PS); determines the number of line pairs that can be resolved if the pixel size is known
b
How many pixels are necessary to image one line? a) 1 b) 2 c) 3 d) 4
c
How many pixels are needed to image a line pair(lp): a) 0 b) 1 c) 2 d) 3 e) undeterminable
c
If a high degree of quantum mottle is noted on an image, the most appropriate solution to correct this exposure error would be to: a) raise the window level higher b) choose a larger pixel size c) repeat the exposure using a higher mAs d) have the patient remove their jewelry for the next exposure
b
If a pixel has a bit depth of 8, this means that the pixel: a) is able to resolve 8 lp/mm b) can produce 256 shades of gray c) the pixel size is 0.8 mm d) contains 8 bytes of information
b
If an anatomical structure is smaller than one pixel: a) only two shades of gray are possible b) the structure will not be visualized c) postexposure image manipulation is not possible d) greater line paris per mm measurements are obtained
a
If pixel density is increased, the image will have/display: a) increased spatial resolution b) decreased spatial resolution c) increased contrast resolution d) decreased contrast resolution
b
If pixel pitch is increased, the image will have/display: a) increased spatial resolution b) decreased spatial resolution c) increased contrast resolution d) decreased contrast resolution
a
If the ,matrix size is constant, then as the FOV increases, the pixel size _ a) increases b) decreases c) stays the same
c
If the FOV increases and the matrix size in unchanged, pixel size will: a) increase b) decrease c) remain unchanged also
a
If the FOV increases and the matrix size reminds unchanged, the contrast resolution will be: a) improved b) degraded
a
If the FOV increases but the matrix is unchanged, then contrast resolution will: a) improve b) decrease
b
If the FOV is constant, then as the matrix size increases, the pixel size _ a) increases b) decreases c) stays the same
a
If the FOV remains unchanged and the matrix size increases, the spatial resolution will be: a) improved b) degraded c) constant
d
If the window width control is opened wider: a) the image will appear denser b) overall brightness will increase c) the image's edges will appear sharper d) more gray shades will be available
noise
Image quality constituted of unwanted or useless background information
b
In general, as image noise increases: a) brightness increases b) contrast decreases c) sharpness increases d) gray scale decreases
a
Increasing the _ would result in a brighter digital image: a) window level b) window width c) bit depth
b
It takes a minimum of _ pixels to image one line pair. a) one b) two c) three d) four
window
Language used by computers
window level
Location on a digital image number scale at which the levels of grays are assigned. It regulates the optical density of the displayed image and identifies the type of tissue to be imaged.
done
Look over Workbook page 119 #3
bit depth
Number of bits that determines the precision with which the exit radiation is recorded and thus controls the exact pixel brightness (gray level) that can be specified.
b
Pixel size = matrix size/FOV a) true b) false
FOV
Portion of the collimated field that contains the anatomy and displayed on the monitor
window level
Post processing function that alters image brightness
window width
Post processing function that alters image contrast or gray scale
c
Refers to the change in appearance of an image as you change the WL or WW(using the mouse): a) resurfacing b) dispersion c) windowing d) mirroring
a
Some advantages of digital imaging over conventional screen/film radiography include: 1. Immediate visualization of the image 2. Ability to adjust the image post exposure 3. Highest spatial resolution possible a) 1, 2 b) 1, 3 c) 2, 3 d) 1, 2, 3
c
Spatial detail in a digital imaging system would be improved MOST by: a) increasing the window width b) decreasing the window level c) increasing the number of pixel s d) decreasing the flux gain of photomultiplier tube
b
Spatial resolution describes the MAXIMUM separation of two objects that can be distinguished as separate objects in the image: a) true b) false
d
Spatial resolution describes: a) the maximum separation of two objects that can be distinguished as separate objects on the image b) the minimum density difference between two tissues that can be distinguished as separate tissues c) the maximum density difference between two tissues that can be distinguished as separate tissues d) the minimum separation of two objects that can be distinguished as separate objects on the image
b
Spatial resolution increases as pixel size _ a) increases b) decreases c) stays the same
a
Term used to describe the "range" or number of different intensities displayed in the image: a) window width b) window level c) window shutter d) window crack
b
Term used to describe the degree of brightness in the image. It is equal to the "midpoint" of the range of intensities displayed: a) window width b) window level c) window pane d) window pain
c
The FOV best describes: a) the number of pixels in a matrix b) the imaging plane that is best demonstrated c) how much of the patient is imaged in a matrix d) the use of multiformat cameras to display images
c
The FOV best describes: a) the number of pixels in a matrix b) the imaging plane that is best demonstrated c) how much of the patient is imaged in a matrix d) the use of multiformity cameras to display multiple images
d
The H & D curve for digital imaging is linear rather than S shaped because: a) more line pairs per millimeter can be imaged b) larger FOV are possible c) radiographic images are displayed in matrices, rather than analog d) of a wider dynamic range
dynamic range
The ability to detect and display a large range of radiographic densities: a wide __
a
The amount of luminance of an image or light displayed by a monitor is termed: a) brightness b) density c) contrast d) spatial frequency
c
The anatomical structures that would cause the greatest degree of x-ray photon attenuation and image brightness would be those that are: a) radiolucent b) radioactive c) radiopaque d) radiodense
a
The average midpoint brightness or intensity level in the image is called the: a) window level b) window width c) bit depth
a
The bit depth if the image pixel determines how many shades of gray it can display a) true b) false
b
The bit depth of a pixel determines the: a) sharpness or recorded detail it can display b) number of intensities or shades of gray it can display c) amount of time it takes to display data
d
The contrast is a digital image is best described as: a) the maximum separation of two objects that can be distinguished as separate objects on an image b) the minimum separation of two objects that can be distinguished as separate objects on the image c) the maximum density difference between two tissues that can be distinguished as separate tissues d) the minimum density difference between two tissues that can be distinguished as separate tissues
contrast
The digital image quality which is controlled by window width.
pixel pitch
The distance or spacing from the middle of one pixel to the middle of an adjacent pixel
two
The minimum number of pixels needed to image one line pair
spatial resolution
The minimum separation at which two objects can be recognized as two separate objects.
gray scale
The number of different shades of gray that can be stored and displayed by a computer system in digital imaging.
b
The number of lp/mm(line pairs per millimeter) is measure of the _ in an image. a) contrast resolution b) spatial resolution c) brightness d) FOV
b
The number of shaded of gray that can be demonstrated in a digital image is affected by: a) matrix size b) bit depth c) FOV d) data compensation
b
The range of the image gray scale is called the: a) window level b) window width c) bit depth
b
The range of the image gray scale is called: a) window b) window width c) center d) window level
d
The statistical fluctuation in image date due to a weak signal is called: a) fog b) resolution c) garbage d) noise
a
The statistical fluctuation of date or intensities in the image is called: a) image noise b) window width c) spatial resolution d) dispersion
a
The use of high-resolution monitors: a) promotes the visibility of anatomical structures b) minimizes the appearance of quantum mottle c) permits the use of increased mAs values d) limits the post processing of a digital image
a
The window control sets the: a) number of density differences in the display b) number of pixels in the matrix c) number of matrices in the pixel d) density value in the middl of the display
b
The window level control is used to alter image: a) contrast b) brightness c) resolution d) signal-to-noise ratio
a
The window width control is used to alter image: a) contrast b) brightness c) signal-to-noise ratio d) resolution
b
To improve contrast resolution, you want a _ Signal to Noise Ratio(SNR): a) low b) high c) weak
contrast resolution
Used to describe the ability of the imaging system to distinguish between small objects that attenuate the x-ray beam similarly in digital imaging
b
What is the pixel size in millimeters of a 256 matrix with a 25 cm FOV? a) 0.1 b) 1.0 c) 10 d) 100
b
What is the pixel size in millimeters of a 512 matrix with a 15-cm FOV? a) 0.03 b) 0.3 c) 3.0 d) 30
b
What is the pixel size in millimeters of a 512 matrix with a 30 cm FOV? a) 0.06 b) 0.6 c) 6.0 d) 60
c
What is the pixel size in mm of a 500 matrix with a 10 cm FOV? a) 50 mm b) 5 mm c) 0.2 mm d) 5000 mm
d
What is the pixel size in mm of a 512 matrix with a 20 cm FOV? a) 25.6 b) 2.56 c) 6.0 d) 0.39 e) 0.039
d
Which matrix size below has the smallest pixel size for a given FOV? a) 128 X 128 b) 256 X 256 c) 512 X 512 d) 1,024 X 1,024
d
Which matrix size has the smallest pixels? a) 128 X 128 b) 256 X 256 c) 512 X 512 d) 1,024 X 1,024
c
Which of the following imaging quality changes is undesirable? a) increased spatial resolution b) decreased contrast resolution c) increased image noise d) increased image matrix size
d
Which of the following is a contributor to image noise? 1. Scatter radiation 2. Plus densities 3. Minus densities a) 1, 2 b) 1, 3 c) 2, 3 d) 1, 2, 3
b
Which of the following will allow more line pairs/mm to be imaged? a) using a smaller matrix b) increasing the number of pixels c) increasing the bit depth d) using a higher frequency signal
b
Which of the following will allow more line pairs/mm to be imaged? a) using a smaller matrix b) increasing the number of pixels c) increasing the bit depth d) using a higher-frequency signal
a
Window width controls: a) the number of density or intensity differences in the image b) the density or intensity value in the middle of the intensity range
d
_ is the average brightness level of the image. a) window width b) window c) density d) window level
contrast
_ resolution; the ability of a system to distinguish between and/or display objects that attenuate x-ray photons differently
a
_ would result in a displayed digital image that is brighter a) increases window level b) decreased window width c) decreased window level d) increased window width
pixel density
number of pixels per unit area.
window width
specific number of gray levels or digital image numbers assigned to an image. It determines the grayscale rendition of the imaged tissue and therefore the image contrast.
brightness
the amount of luminance (light emission) of a display monitor
pixel pitch
the pixel spacing or distance measured from the center of a pixel to an adjacent pixel
dynamic range
the range of exposure intensities that an image receptor can respond to and acquire image data.
