Chapter 15

The increased number of pixels in the region of interest improves

.spatial resolution.

A bit is bistable, having a value of either

0 or 1.

Binary numbers are based on only two choices,

0 or 1.

Analog scan converters are now obsolete because of the following limitations/disadvantages

Image fade, Image flicker, Instability, Deterioration

One of the advantages of digital scan converters, Durability, explained

Is not affected by age or heavy Use

LCD stands for

Liquid crystal display

___ are digital display devices.

Modern flat-panels

How many possible shades of gray are displayed with 5 bits of memory?

Multiplying 2 by itself 5 times yields: 2 x 2 x 2 x 2 x 2 =32

each pixel can only have ___ color

One

is the number of picture elements per inch.

Pixel density

Does the sonographer control pre-processing?

Yes

With magnification (or ___) the anatomic detail by enlarging a portion of sonographer can improve visualization of an image to fill the entire screen.

Zoom

Write magnification is characterized by: The image used to identify the ROI is discarded and all new image information is ___ The number of pixels or scan lines in the ROI image is greater than that in___

acquired. the ROI's portion of the original image.

Converting information from analog to digital form is ___ because digital information is far less susceptible to contamination.

advantageous

Postprocessing is the manipulation of image data ___ storage in the scan converter.

after

Read magnification occurs ___ the image data is stored in the scan converter.

after

A computer mouse is an ___ converter.

analog-to- digital

Electrical signals created by the transducer during reception are converted from analog to digital form by the___ converter

analog-to-digital (A-to-D)

One of the advantages of digital scan converters, Acccuracy, explained

error-free.

Translating image information from the real world (analog) to the computer world (digital) and back again is a ___ step process

five-

Write magnification cannot be used on a ___ and thus, is preprocessing.

frozen image

Preprocessing alters the image data forever and cannot

he reversed or undone.

Newer Modern flat panel computer display technologies are desirable since they provide ___ with more lines per image when compared to traditional televisions.

higher frame rates

Coded excitation is a sophisticated method of improving

image quality

Read magnification of the ROI creates

larger pixels from the information that is already in the scan converter.

Write magnification rescans the region of interest and Creates a new image with increased

spatial resolution.

The scan converter translates the information from the ___ into the___

spoke format, video format

One of the limitation/disadvantages of analog scan converters... How does Image fade occur

stored charges on the silicon wafer dissipate over time.

One of the limitation/disadvantages of analog scan converters... Image flicker occures by

switching between read and write modes

Decimal numbers, which are used in everyday life, are based on

ten choices, 0 through 9.

With write magnification, temporal resolution may be improved if

the bottom of the region of interest is shallower than the original image's depth of view

Each pixel's shade of gray is determined by

the cluster of bits assigned to it.

Read magnification occurs after the image data is stored in

the scan converter.

A word of computer memory consists of

two bytes, or 16 bits.

When using a digital display device, step 4, digital-to-analog conversion, is

unnecessary.

A ___ of computer memory consists of two bytes, or 16 bits.

word

The data stored in the scan converter can be altered between the ___and the___

writing process, reading process.

Digital scan converters use computer technology to convert images into numbers, a process called digitizing. The image is stored in computer memory as a series of

zeroes and ones.

The word bit, derived from the term

"binary digit"

Later, image data is ___ from the scan converter for display on the monitor.

"read"

Storage of the image information in the scan converter is called

"writing."

Spatial resolution is also known as

. "image detail."

Advantages of digital scan converters include

Uniformity, Stability, Durability, Speed, Accuracy

At any instant in time, the entire pixel is a

single shade of gray

Write Magnification consists of four steps

1. The ultrasound system scans the anatomy and creates an image. 2. The image is converted from analog to digital form and is stored in the scan converter. 3. The sonographer identifies the region of interest. At that moment, the system discards all the existing data in the scan converter. 4. The ultrasound system then rescans only the region of interest and writes new data into the scan converter.

Two different forms of magnification exist:

1. read magnification 2. write magnification

With a digital scale, a person who actually weighs 163.12 pounds will be reported as weighing ___ pounds.

163

The prefix "bi-" means

2.

picture element is

A Pixel

What are the 5steps of image translation

A to D conversion, pre-processing, digital storing and post processing, D to A conversion, and display on analog monitor

___ are "real world" numbers that are found in our everyday lives.

Analog numbers

the first scale imaging type of scan converter and made gray possible.

Analog scan converter

Types of display are

Analog, LCD, plasma display, Amoled

Preprocessing is the manipulation of image data ___ storage in the scan converter.

Before

___ is the smallest amount of computer memory.

Bit

___ determines the brilliance of the displayed image

Brightness

___ determines the range of brilliancies within the displayed image. Bistable images, in which only white and black appear, are high contrast

Contrast

___ which are used in everyday life, are based on ten choices, 0 through 9.

Decimal numbers,

___ numbers are associated with computer devices.

Digital

is the manipulation of image data after storage in the scan converter.

Postprocessing

is the manipulation of image data fore storage in the scan converter.

Preprocessing

___ improves with high pixel density and creates an image with greater detail

Spatial resolution

___ may be thought of as a picture divided into millions of tiny dots, each containing an electrical storage element (or electron bucket).

The dielectric matrix

Read magnification is characterized by:

The number of pixels or scan lines in the magnified image is the same as in the original image.

___ of an analog scan converter is excellent because of the large number of storage elements within the matrix.

The spatial resolution, or image detail,

Read magnification consists of three steps including

The ultrasound system scans the anatomy. The image is converted from analog to digital form and is stored in the scan converter. sonographer identifies the region of interest, and the system reads and displays only the original data that pertains to the region of interest. The ROI is not rescanned.

Write magnification is applied during data acquisition, ___ storage in the Scan converter.

before

is a group of bits and is simply a series of zeroes and ones, such as 0101010011.

binary number

___ images are composed of only 2 shades: black and white

bistable

A ___ is a group of cight bits of computer memory, such as 10011111.

byte

The Two user controls on video monitors, contrast and brightness, can alter what

characteristics of displayed images

One of the advantages of digital scan converters, uniformity, explained

consistent gray scale quality throughout the image.

Analog numbers can have an unlimited and ___ range of values.

continuous

Images with many gray shades have better

contrast resolution.

The scan converter changes the format of

data.

One of the limitation/disadvantages of analog scan converters... Deterioration occurs by

degrades as the device ages.

Modern ___ scan converters use computer technology.

digital

Converting information from analog to digital form is advantageous because

digital information is far less susceptible to contamination.

From the term picture element, the pixel is the smallest building block of a

digital picture.

Digital signals cannot be directly displayed on analog display devices. The digital signals must be translated back into analog form by a

digital- to-analog (D-to-A) converter.

An iPod is a ___ converter.

digital-to-analog

Digital scan converters use computer technology to convert images into numbers, a process called

digitizing.

digital numbers have only ___ values.

discrete

One of the advantages of digital scan converters, Stability, explained

does not fade or drift.

A byte is a group of

eight bits of computer memory,

The dielectric matrix may be thought of as a picture divided into ___ each containing an electrical storage element

millions of tiny dots,

To determine or calculate the number of gray shades that can be represented by a cluster of bits, what do you do

multiply the number by itself the same number of times as there are bits: 2number of bits or 2n

One of the advantages of digital scan converters, Speed, explained

nearly-instant processing.

The increased number of pixels in the region of interest improves.spatjal resolution. The pixels are the same size in both the

old and the zoomed image.

Ultrasound data is acquired from ___ into the body. Video is presented as ___ lines. The scan converter converts the ___into a ___

penetrations, horizontal, penetration pattern into a horizontal line pattern.

One of the limitation/disadvantages of analog scan converters... Instability occurs by

picture quality depends on many factors including length of use, room temperature, and humidity.

More detail and improved spatial resolution are associated with higher ___ density

pixel

Two important elements of digital scan converters are:

pixel, bit

Any processing after storage in the digital scan converter is called

postprocessing.

Read magnification can be used on a frozen image and is

postprocessing.

Any processing of the reflected signals before storage is called

preprocessing.

ROI stands for

region of interest,

The selected part of the image during magnification is known as the

region of interest, or ROI

Since postprocessing occurs after A-to-D conversion (digitization) and storage, all postprocessing changes can be___ Which will restore the initial values of the image data

reversed,

Gray scale imaging was initially made possible with the use of___, which first store information and later display it.

scan converters,