Imaging Final 3

If the field of view is 500 mm and the matrix is 1024, what are the pixel dimensions?

0.49mm x 0.49mm

A method of describing the strength of the radiation exposure compared with the amount of noise apparent in the digital image is the:

signal-to-noise ratio

A 10-bit depth can display how many shades of gray?

1024

Which of the following is the sequence of events, from beginning to end, of what happens in the CR reader unit: 1) Analog electrical signal is sampled and digitized 2) Stored energy is released as visible light 3) PMT converts light energy to electrical signal

2,3,1

Which of the following is the sequence of events, from beginning to end, for production of a DR imaging using direct conversion detectors? 1) Image matrix is formed in computer 2) Charge is briefly stored in TFT array 3) Exit radiation is converted to electrical charge 4) Electronic signal goes to ADC

3,2,4,1

Diagnostic interpretation should be done at a high-resolution ___ display monitor.

5 megapixel

Digital imaging processing refers to:

A computer manipulations applied to digital images

Pixel bit depth is determined by the:

ADC

Soft copy viewing means that the image is being viewed:

At a computer

The monitor matrix size should be ___ the image matrix size.

At least as large as

Based on the histogram analysis, consistent image brightness is accomplished through:

Automatic rescaling

The communication standard for information sharing between PACS and imaging modalities is the:

DICOM

Increasing the number of line pairs per millimeter resolved in the imaging system results in:

Higher spatial frequency and increased spatial resolution

The number of bits that determines the amount of precision in digitizing the analog signal and the number of gray shades that can be displayed in the image is the:

Bit depth

The ___ provides a method of altering the image to change the display of the digital image.

Lookup table

An example of a scintillator used in an indirect conversion detector is:

Cesium iodide and gadolinium oxysulfide

A method of describing the contrast resolution compared with the amount of noise apparent in a digital image is the:

Contrast-to-noise ratio

The higher the DQE of a system, the radiation exposure required to produce a quality image is:

Decreased

Decreasing the window level will result in an image with:

Decreased brightness

With CR, a higher sampling frequency results in ____ pixel size and _____ spatial resolution.

Decreased; increased

The measurement of the efficiency of an image receptor in converting the x-ray exposure it receives to a quality radiographic image is the:

Detective quantum efficiency

Which of the following is not part of a CR reader unit? A) Optical system B) ADC C) Photodetector D) Developer tank

Developer tank

A value that reflects the difference between the desired or target exposure to the IR and the actual exposure to the IR is the:

Deviation index (DI)

The DICOM GSDF is used to evaluate the:

Display monitor

The ability of the detector to accurately capture the variety of photon intensities in the remnant radiation is:

Dynamic range

The post processing technique improve the visibility of small, high contrast structures.

Edge enhancement

Which of the following is not a component of the CR IP? A) emulsion layer B) support layer C) phosphor layer D) protective layer

Emulsion layer

In CR imaging, the ___ of the imaging plate is scanned.

Entire area

With CR, when the x-ray photons are absorbed by the phosphor, the ___ atoms become ionized.

Europium

The numerical value indicating the level of radiation exposure to the digital IR is the:

Exposure indicator

An image with high SNR will have decreased detail visibility: T/F

False

Because digital imaging has a large dynamic range, significantly lower than necessary x-ray exposure will still result in a quality image. T/F

False

Bit depth is determined by the matrix size. T/F

False

Both CR and DR are electronic detectors that combine image capture and image readout: T/F

False

Exit radiation is converted to visible light with the direct conversion detector. T/F

False

There is no light produced with CR when radiation interacts with the IP. T/F

False

The percentage of x-rays that have reached the detector and have been captured is the:

Fill factor

___ can be removed from the Bucky and is used on the tabletop or stretcher.

Flat-panel detector

The communications standard for medical information is:

HL7

A CRT type monitor:

Has a fluorescent screen, uses an electron gun, and scans in lines

The size of a pixel is measured in:

Inches

The histogram analysis represents the ___ for different exposure controls.

Incidence of pixels

A system that can digitize and display a greater number of shades of gray will have ___ contrast resolution.

Increased

Which of the following results in improved spatial resolution?

Increased pixel density and decreased pixel pitch

With CR, a higher sampling pitch results in _____ pixel size and _____ spatial resolution.

Increased; decreased

With CR, a higher sampling frequency results in ____ pixel density and _____ spatial resolution.

Increased; increased

A large bit depth:

Increases contrast resolution

A large bit depth:

Increases the number of shades of gray

___ the CNR increases the visibility of anatomic details.

Increasing

___ the SNR increases the visibility of anatomic details.

Increasing

Immediately before leaving the CR reader unit, the IP is exposed to:

Intense white light

With a fixed matrix CR reader system, changing to a larger IP, for the same FOV, will result in:

Larger pixels

LCD stands for:

Liquid Crystal Display

Which of the following passes light through liquid crystals to display the image on the glass faceplate?

Liquid crystal display monito

Increasing the window width will result in an image with:

Lower contrast

What is the term generally used to describe the emission of light from a substance as the result of stimulation by radiation?

Luminescence

Which of the following is not accomplished through the histogram analysis?

Manipulation of image contrast

The distracting area of increased brightness surrounding a collimated image can be removed from the displayed digital image by:

Masking, shuttering, electronic collimation

A combination of rows and columns (array) of pixels is called a:

Matrix

The greater the pixel bit depth, the ___ the digitization of the analog signal, and the ___ the number of shades of gray available for image display.

More precise; greater

All of the data from the entire IP (including scatter outside the exposed field) may be included in the histogram analysis if:

Only one edge of the collimated field is identified

The computer system designed to distribute, store, and display digital images is:

PACS

The ___ collects, amplifies, and converts visible light to an electronic signal.

PMT

Which of the following is not a component of a flat-panel detector?

Phosphor layer

The emission of light when stimulated by a high-intensity laser beam is:

Photostimulable luminescence

This material is composed of barium fluorohalide and makes up the primary component of the CR IP.

Photostimulable phosphor

The pixel spacing or distance measured from the center of a pixel to an adjacent pixel is called the:

Pixel pitch

With CR, trapped electrons are:

Proportional in number to the tissue's x-ray absorption and released during the readout stage

A high SNR means that the:

signal strength is high

Which of the following exposure indicators has an inverse relationship with exposure to the IP? A) EI (Carestream) B) IgM (Agfa) C) S number (Fuji) D) All have an inverse relationship

S number (Fuji)

Which of the following changes in the exposure indicator values does not represent a doubling of radiation exposure to the IR? A) S number (Fuji) changing from 200 to 400 B) S number (Fuji) changing from 400 to 200 C) EI (Carestream) changing from 1200 to 1500 D) EI (Carestream) changing from 1500 to 1800

S number (Fuji) changing from 200 to 400

The distance between the analog points being sampled is the:

Sampling pitch

The indirect conversion detector uses:

Scintillator and photodetector

This post processing technique reduces the visibility of image noise

Smoothing

DR imaging systems briefly store the electrical charge in the:

TFT

The ___ array is divided into square detector elements (DEL).

TFT

Overexposing a digital image receptor may result in a quality image, but:

The ALARA principle has not been followed

Which of the following is true concerning computed radiography imaging plates? A) The CR cassette houses the imaging plate B) The radiation exiting the patient interacts with the imaging plate C) The photon intensities are absorbed by the phosphor D) All of the above

The CR cassette houses the imaging plate, the radiation exiting the patient interacts with the imaging plate, and the photon intensities are absorbed by the phosphor

If the field of view is increased for a fixed matrix:

The pixel size is increased

Once the data is in digital format, there is not difference between image processing and display between CR and DR: T/F

True

The DQE is higher for DR when compared to CR. T/F

True

The DR system does not require a separate reader unit. T/F

True

The dynamic range of a digital imaging system is significantly larger than a film-screen system. T/F

True

The spatial resolution of flat-panel receptors is generally superior to that of CR. T/F

True

With an FPD, electrical charges from each DEL are read out separately: T/F

True

The range of the histogram data set that should be included in the displayed image is determined by the:

VOIs

The DR detector array is typically located:

Where you would normally find the Bucky tray

Because digital IRs have a linear exposure response and wide dynamic range, raw data images appear:

With low contrast

Which of the following is true about the indirect conversion DR systems?

X-rays are converted to light then converted to electrical charges

If the matrix is increased for a given FOV:

a. spatial resolution is increased

The CR phosphor layer is composed of:

barium fluorohalide with europium

The pixel bit depth determines the image's:

contrast resolution

Compared with film-screen detectors:

digital IRs have a much wider dynamic range.

The CR latent image consists of:

electrons trapped in the phosphor layer

In the CR reader unit, the IP is scanned with a(n):

helium-neon laser beam

Digital image quality is improved with:

larger size matrix and smaller size pixels

An MTF of 1.0 means:

maximum difference in brightness levels

The measure of the imaging system's ability to display the contrast of anatomic objects varying in size is the:

modulation transfer function

The number of pixels per unit area is called the:

pixel density

How often the analog signal is digitized is the:

sampling frequency