RAD 274 Quiz 3

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

1,2,& 3

Which of the following is a contributor to image noise? 1. Scatter radiation 2. plus density artifacts 3. minus densities artifacts

1,2,&3

What is the pixel size in millimeters of a 256 matrix with a 25 cm field of view?

1.0 mm Pixel size= FOV / matrix

Of the following: Which matrix size has the smallest pixels? 128 x 128 256 x 256 512 x 512 1024 x 1024

1024 x 1024

The device that is needed to allow computer processing of an analog signal is a/an:

ADC (analog to digital converter)

Contrast resolution in a digital image: A. Is the ability of a imaging system to display a short scale of contrast B. Is the ability of a system to display a large number of shades of gray C. Is the ability of an imaging system to display very bright pixels D. Is controlled by the number of pixels and pixel bit depth

BOTH B&C

Contrast resolution in a digital image: A. Is the ability of a imaging system to always display a short scale of contrast B. Is the ability of a system to display a large number of shades of gray C. Is the ability of an imaging system to display very bright pixels D. Is controlled by the number of pixels and pixel bit depth

BOTH B&D

if FOV decreases and the Matrix size remains the same: Pixel size will _____ and spatial resolution will _____

Decrease, Increase

if FOV remains constant and the matrix size increases: Pixel size will _____ and spatial resolution will _____

Decrease, increase

if FOV increases and Matrix remains the same: Pixel size will _____ and spatial resolution will _____

Increase, Decrease

If FOV remains constant and the matrix size Decreases: Pixel size will _____ and spatial resolution will _____

Increase, decrease

The latent image in a CR imaging plate is stored by the:

The latent image in a CR imaging plate is stored by the:

In order to view a digital image that has been exposed on a phosphor plate cassette, what "processing" equipment is needed?

a laser reader

A digital matrix is made up of:

a matrix of pixels

The IR Exposure response curve for digital imaging is linear rather than S-shaped because:

a wider dynamic range

Any unwanted information on an image is the definition for:

artifacts

The active layer in the photostimulable phosphor of a CR imaging plate is typically made of:

barium fluorohalide

language used by computers

binary

calculated using the formula 2n; reports the number of gray shades available

bit debth

The number of shades of gray that can be demonstrated in a digital image is affected by:

bit depth

The amount of luminance of an image or light displayed by a monitor is termed:

brightness

The amount of luminance of an image or link displayed by a monitor is termed:

brightness

The window level control is used to alter image:

brightness

amount of luminance an image displays on a monitor

brightness

If a pixel has a bit depth of 8, this means that the pixel: ( hint--- 2n)

can produce 256 shades of gray

The window width control is used to alter image:

contrast

resolution; the ability of a system to distinguish between and/or display objects that attenuate x-ray photons differently

contrast

In general, as image noise increases:

contrast decreases

If pixel pitch is increased, the image will have/display:

decreased spatial resolution

the ability to detect and display a large range of radiographic densities: a wide ______

dynamic range

Before a computed radiography imaging plate can be reused, it must be:

erased with a high intensity light

portion of the collimated field that contains the anatomy and displayed on the monitor

field of view

On a PA projection of the wrist, you notice what appears to be a soft tissue mass superimposed over the bony anatomy in the digital DR image. When you inspect the patient, you notice the presence of a large linear scar from a previous injury. The visualization of this scar in the image is primarily due to what characteristic of digital detectors?

high contrast resolution

The field of view (FOV) best describes:

how much of the patient is imaged in a matrix

One of the advantages of digital imaging is: -several visual cues are present that indicate over or under exposure of the image - images can be easily sent to remote locations - the image is permanently fixed, preventing post-exposure adjustments - it represents a continuous and analog range of signal

images can be easily send to remote locations

If the field of view remains unchanged AND the matrix size increases, then the resulting spatial resolution will be _____ because the pixel size will decrease.

improved

IF the field of view (FOV) increases AND the matrix size is unchanged, then the resulting pixel size MUST ________ and as a result the spatial resolution will decrease.

increase

Which of the following image quality changes is undesirable? - increased spatial resolution - increased contrast resolution - increased image noise - increased image matrix size

increased image noise

If pixel density is increased, the image will have/display: - increased spatial resolution - decreased spatial resolution - increased contrast resolution - decreased contrast resolution

increased spatial resolution

Spatial detail (resolution) in a digital imaging system would be improved MOST by: - increasing window width - decreasing window level - increasing the number of pixels - decreasing the flux gain of the photomultiplier tube

increasing the number of pixels

Which of the following will allow more line pairs per millimeter to be imaged? - using a smaller matrix - increasing the number of pixels in the matrix - increasing the bit depth - using a higher frequency signal

increasing the number of pixels in the matrix

The purpose of europium "doped" in the photostimulable phosphor is to:

it acts to trap(store) the electrons (metastable e-)

array of cells arranged in columns and rows

matrix

If the window width control is opened wider (a larger range):

more gray shades will be available

If the window width control is opened wider:

more gray shades will be available

image quality constituted of unwanted or useless background information

noise

The device that converts the light emitted by an exposed PSP inside the computed radiography (CR) reader into an electric signal is the:

photodiode (photodetector)

each cell in a matrix is called

pixel

the distance of spacing from the middle of one pixel to the middle of an adjacent pixel

pixel pitch

The use of high-resolution monitors: (High resolution means a monitor with a large matrix size)

promotes or improves the visibility of anatomical structures

The process of assigning number values to each pixel in proportion to the energy received best describes:

quantization

assigns a value to each pixel relative to the energy it received

quantization

The anatomical structures that would cause the greatest degree of x-ray photon attenuation and image brightness would be those that are:

radiopaque

If a high degree of quantum mottle is noted on an image, the most appropriate solution to correct this exposure error would be to:

repeat the exposure using a higher mAs

process of detecting and measuring exposure received by the detector

sampling

process of dividing image up into a matrix, each cell becomes a pixel

scanning

The laser in a CR reader...

scans the exposed phosphor in a raster pattern

formula to calculate this is 1/2 (PS); determines the number of line pairs that can be resolved if the pixel size is known

spatial frequency

After exposure, the remaining steps for acquiring a computed radiography image, in order, are:

stimulation, reading, and erasing

the minimum number of pixels needed to image one line pair

two

postprocessing function that alters image brightness

window level

postprocessing function that alters image contrast or grayscale

window width