RAD 280 Chapter 20

The relationship btwn DQE and MTF:

How does the computer correct over/underexposure?

Is the effect of the bit depth:

What is spatial resolution or image sharpness determined by?

Improved low-contrast resolution means the IR has a _____ dynamic range.

The overall dimension of the image matrix:

Processing operation used to change position/orientation of the pixels in the image to allow for rotation &magnification

When random background information is detected, it contributes to image quality

The number of shades of gray is determined by

Audio noise, such as static:

Who sets the target acceptable ranges of exposure indicator values to give the best image quality?

Point processing is the most common processing operation in digital radiography systems

A measure of the sensitivity & accuracy by which the IR converts the incoming data to the output viewing device:

What is the DQE of most digital radiography systems?

The electronic devices that produce radiographic images, by design produce ______ signals

The analog signals need to be converted to a binary langue through which process?

Uses an algorithm to convert the image into spatial frequency domain. Produces a sharper output image/enhanced edges

Result of insufficient qty of photons from improperly set exposure factors.

Performed btwn the receipt of the input image from the IR and the output image that is viewed on the monitor

Uses a photostimulable storage phosphor imaging plate (PSP). The cassette is taken to a reader.

The relationship btwn DQE and SNR:

Local processing operations are those in which a math calculation is applied to a ____ group of pixels.

Image subtraction & temporal averaging are considered point processing operations but used mostly in angiography

Each binary number is called:

An 8 word bit

A narrow width has ____ shades of gray and the image will have _____ contrast.

If the FOV remains the same, then as the matrix size _______, the pixels must get ________, to create a sharper image

A series of boxes laid out in rows and columns that give from to the image

Processing code that is mandatory and common to the computer system

Has a detector and reader as permanent parts and doesn’t always need a cassette

Background radiation:

The exposure indicator ranges the department sets is based on manufacturer specifications.

What detective quantum efficiency would a perfect device have?

Windowing is a point processing operation that affects what?

The resolution (object size) and the contrast

Controlled by the matrix size and how many pixels can be displayed on the monitor:

Used to measure the capacity of the detector to pass its spatial resolution characteristics for the final image.

High image contrast tends to obscure or decrease noise.

The ability of the detector to resolve different energies striking it and transfer the energies into signal values

Small structures produce ____ frequency and ____ contrast

What does a narrow histogram demonstrate?

Subtracts a low-pass filtered image from the original image to produce a sharper image. Also called blurring

Reflect the amount of x-ray exposure to the IR, which looks at the qty of photons striking the receptor.

An individual matrix box that represents a 2D data point

Each box of the image matrix displays a numerical value that is transformed into visual brightness/density levels

The grayscale bit depth ranges from 8 bits to 32 bits (2n^2).

The pixel location

The 3D data point that is called a volume element

A high DQE indicates that MORE radiation is necessary to achieve identical image quality than a lower DQE would produce

The comparison btwn the actual exposure and the proper exposure received by the image detector

In this step of ADC, each sampled piece of the analog data is computed and assigned a discrete analog value

What is spacial frequency filtering NOT used for?

With DR systems, the image is sent directly to the display monitor

Improved low-contrast resolution does NOT improve the visualization of pathologies on digital images.

What does a wide histogram demonstrate?

In DR systems, what is the FOV determined by?

If there is little noise in the image, the SNR is ______.

Which is expressed as varying grayscale levels?

Resolves differences in structures. The ability to see subtle energy differences, especially in soft tissues.

Results in greatly increased contrast

Point processing operation that changes the contrast and brightness of an image on the monitor:

The proper LUT will provide the proper grayscale, regardless of changes in kVp, mAs

When does spatial resolution increase?

Decreases image detail, which is not wanted:

A large width has ____ shades of gray and the image will have _____ contrast.

DR systems are either direct or indirect conversion

Spacial frequency filtering is what type of what type of processing operation?

What are the 2 steps of CR?

Goes directly to an electronic signal

If the comparative values for the histogram are low, how does the image appear?

If the comparative values for the histogram are high, how does the image appear?

The mathematical algorithm applied to change an image from spatial location domain to spatial frequency domain

The _____ of a histogram will correspond to the specific anatomy and technique used for an exam

Selecting the proper projection is not relevant to ensuring that the proper LUT will be applied to the processed image

In this step of ADC, the analog voltage values are measured at a chosen frequency on the analog waveform.

A _____ is applied to the data that has the standard contrast for that exam to give it the desired image contrast

Noise that results from undesirable signals from the digital system itself:

The ______ the matrix size for the same FOV, the ______ the spatial resolution

Quantum noise produces a grainy image that can be corrected by increasing mAs or kVp, depending on the situation

The range of shades of gray that will be displayed:

What is noise measured as?

What MTF would a perfect detector have?

The larger matrix provides _______ pixels.

Intentionally blurs the image to reduce noise and the brightness level of the pixels. Also called smoothing

The scanned area of the histogram is divided into pixels and the signal intensity for each pixel is determined

If there is more noise, image contrast is ______.

2-part system using a scintillator and photodetector

A ______ is generated during initial processing from the image data