RADI 172 Final

___________________ replaces the visual cues of density and contrast used in analog imaging systems.

exposure indicators

This is defined as the degree of geometric unsharpness or accuracy of structural lines recored in the image.

detail, definition, spatial resolution

How many shades of gray are possible with a 6 bit system?

64

Cassette-based digital radiography systems uses a ____________________ inside an imaging plate.

photostimulable storage phosphor

Digital images are made of discrete picture elements, or _____________________, arranged in a matrix.

pixels

With "direct digital" radiography, a cassette is not needed.

true

Direct acquisition systems utilize this as the detector.

amorphous selenium

With cassette-based digital systems, a thin film transistor (TFT) and individual detector elements collect the image.

false

In digital radiography, this type of system uses a two-part process that involves both a scintillator and a photodetector.

indirect acquisition

These collect the electrons given off by Amorphous Selenium or Amorphous Silicon.

DEL's

The two types of plate scanning mechanics found with cassette-based digital imaging include:

line scan and flying spot scan

What happens to the patient dose if I have a high DQE?

patient dose is decreased

As DQE decreases, the noise in a digital image is reduced.

true

An underexposure greater than 50% results in a loss of image contrast.

false

What is the function of a scintillator?

converts incoming x-ray photons to light

_______________________ is the range of under or overexposure that can occur in producing an acceptable image and does not violate ALARA.

exposure latitude

In digital imaging, exposure level and spatial resolution are closely associated.

false

With Carestream digital imaging systems, doubling the exposure increases the EI by 300.

true

With digital imaging, the latent image loses about ______________ of its energy in approximately 8 hours.

25

Digital imaging systems have an extremely high tolerance for patient overexposure.

true

This refers to the operational exposure level at which a digital imaging system is operated.

speed class

ADC stands for:

analog-to-digital converter

Smaller pixels equals greater detail.

true

With PSP imaging plates, the barcode reader must be read/scanned before an exam is performed.

false

With digital imaging, if the exposure field is not recognized accurately, a histogram analysis error followed by a rescaling error might occur.

true

The light guide assembly works much like fiber optic technology.

true

This device measures the exposure levels at the collimator and calculates as ESE based on this measurement.

DAP meter

___________________ is the reason why digital imaging systems can produce an image even when significant exposure error occur.

automatic rescaling

Direct acquisition radiography converts incoming x-rays directly to an electronic signal.

true

Which of the following vendors/brands utilizes a sensitivity number as their exposure indicator?

fuji, philips, konica

This may result in histogram analysis errors and rescaling errors.

inappropriate collimation and inappropriate beam alignment

Prior to image creation, the exposure values extracted from the PSP plates are subject to a process known as:

quantization

Excessive processing could result in an inaccurate dictation/diagnosis due to inappropriate default processing.

true

Quantization may sometimes be referred to as:

sampling frequency

With Priori Histogram Analysis, the standardized set of data comes from two or more pre-defined histograms.

false

The predetermined values used to create the digital image are known as:

values of interest

PSP's respond to an exposure as low as ____________ micro-roentgens.

60

Scatter radiation is not part of the useful beam.

true

Ways at reducing scatter radiation include which of the following:

beam limiting, optimal exposure, grid use, utilizing compression bands

Examples of beam limiting devices include all of the following except:

grids

With Neutral Histogram Analysis, a digital image is created after extracted data is matched to exams derived from experience of like subjects under ideal conditions.

false

Spatial resolution is one of the principal factors affecting the amount of scatter radiation produced.

false

Changes in kVp will not greatly affect radiographic contrast as it did with film-screen combinations.

true

To help avoid the Moire Effect a technologists should:

make sure that the grid line is not running in the same direction as the laser beam that is scanning the PSP, use high-frequency grid, use a grid with 103-178 lpi

Automatic rescaling can also be referred to as auto-ranging, rescaling, scaling, and normalization.

true

If you see gray areas outside the exposure field borders, a PSP exposure field recognition error might have occurred.

true

______________________ described the concept of density as it is displayed on a soft-copy monitor for digital image viewing.

brightness

Image contrast describes the difference between adjacent densities.

true

Excessive edge enhancement may cause this type of artifact:

halo

Digital filtering transforms images into their corresponding ____________________.

frequencies

Low-pass filtering may also be classified as smoothing and/or noise suppression.

true

smoothing greatly improves edge visibility.

false

Too much equalization can result in a poor image.

true

High-pass filtering either amplifies or deletes all but the low frequencies.

false

Scatter radiation is produced during _______________________ interaction.

compton

High-pass filtering may also be referred to as edge enhancement.

true

Equalization is a software function designed to even out the noise displayed in a digital image.

false

___________________ graphically represent a collection of exposure values extracted from the digital image receptor.

histograms

This term describes excessive equalization caused by a metal prosthesis.

metal mottle

An important step in the analysis of image data is recognizing exposure field borders.

true

The probability that an x-ray will interact with an image receptor depends on which of the following:

thickness of capture layer, atomic composition

Digital systems can be operated at a wide range of exposures, therefore making the term "speed" an inappropriate descriptor.

true

This is a measure of x-ray absorption efficiency.

DQE

Characteristics of PSP's include the following:

phosphor types, conversion efficiency, system speed class, detective quantum efficiency

With digital imaging systems, contrast is now unrelated to dose unlike analog film-screen systems.

true

You can not and should not collimate with digital imaging systems because it could result in a histogram error.

false

A partial loss of row of DEL's can be fixed easily because all you have to do is replace the individual DEL or row of DEL's.

false

Digital imaging systems are more sensitive to scatter and background radiation than analog film-screen systems.

true

With digital imaging systems, your kVp may be ___________________ higher than with analog film-screen systems.

5-15

________________________ is the rate at which x-ray energy is transformed into light in an intensifying screen.

conversion efficiency

With digital imaging systems, an additional 0.1-0.2 mm of copper filtration is recommended to reduce patient dose.

true

rescaling forces radiographers to look elsewhere for signs that a proper exposure was used to produce an image.

true

DQE is highest for __________________ systems and lowest for __________________ systems.

DR, analog film-screen

_____________________ refers to the tendency, with digital radiography, to gradually increase patient dose over time.

dose creep

You do not need to use a grid with digital imaging systems.

false

Digital imaging blur is caused by motion and changes in geometric factors.

true

needle crystals result in more light divergence when stimulated compared to turbid phosphor material.

false

Digital imaging is mAs driven.

false

Suggested ways aimed at controlling patient exposure with digital imaging systems include which of the following:

additional filtration, higher kVp levels, interfacing with AEC, maintain ALARA principles

Common image capture elements utilized with digital image receptor include all of the following except:

CaS

With the advent of digital imaging systems, it has become a lot harder for patient dose to be monitored.

false

Three main types of acceptance testing include all of the following except:

dark noise evaluation

Daily test regarding quality assurance includes what?

visual inspection, plate reader inspection, laser printer QC, monitor QC

Monthly QA test include all of the following:

PSP plate erasure, phantom image test, monitor calibration

Excessive dark noise improves the digital image.

false

Failure to demonstrate a uniformly bright image means that there may be a problem with the PSP plate or the reader (processor).

true

With image brightness uniformity, a ______% variation in pixel value is allowed.

10

Regarding digital imaging QA, this test assesses pixel values.

linearity and slope

With this test, a radiograph is processed through the PSP reader to determine if its edges, of the displayed image, are straight and continuous.

laser beam function

The high contrast resolution test uses a grid that measures line pairs per millimeter to assess the high contrast resolution capability of PSP systems.

true

If PSP imaging plate is not throughly erased, noise will be added to the next image.

true

The wire mesh test is utilized to access ___________________.

distortion

The daily monitor test is performed using which of the following test tool devices?

SMPTE test pattern, TG18QC test pattern

Part of the daily plate maintenance and cassette inspection involves checking the PSP imaging plate for cracked or broken hinges.

true

PSP imaging plates should be erased at least every 48 hours if they have not been in use.

true

If you come across a cracked or broken PSP imaging plate, just throw it in the garbage. It doesn't matter how you dispose it.

false

This refers to the number of pixels in a matrix and the size of the display screen.

spatial resolution

when viewed in a landscape format, lcd monitors typically have an aspect ratio of 4:3.

false

The gaps between pixels where no image information is displayed is called:

dead space

A bit depth of 1 equals a monochrome color display.

true