Chapter 15

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to determine the number of gray shades that can be represented by a cluster of bits, multiply the number of ___ by itself the same number of times as there are bits. The result is the max number of different shades of gray

2

multiple penetrations, or spokes, are needed for each __________ image, however, monitors display video info as ___________ lines

2D, horizontal

what is the number of shades that can be represented by 10 bits?

2^10= 1024

what is the number of shades that can be represented by 3 bits? (pg 261)

2^3= 8

How many gray shades can be represented by a group of 4 bits? 2 bits?

2^4= 16 2^2= 4

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

2^5= 32

what is the number of shades that can be represented by 8 bits?

2^8= 256

what is the number of shades that can be represented by n bits? (pg 262)

2n

how many bits are needed to store 10 shades of gray? 11 shades of gray? 15 shades of gray? (pg 262)

4

What is a set of rules, or protocols, that allows imaging systems to share info on a network?

DICOM

When a particular ultrasound system adheres to _______ standards, the system can successfully connect to a PACS medical info network

DICOM

who has established maximum peak intensity levels for sound beams?

FDA

what are 3 major advantages of PACS? (pg 259)

Instant access, no degradation, electronically transmit images

Not only does DICOM assure that current imaging modalities can communicate, it guarantees that all devices developed in the future will easily attach to the _______ network as well

PACS

what is a computer system that not only allows acquisition, but also the interpretation, storage and recall of each medical image in digital form.

PACS system

PACS stands for what?

Picture archiving and communications system

With frequency compounding, how many pulses are transmitted down each scan line? a. 1 b. 2 c. 4 d. cannot be determined

a

which of the following technologies uses long sound pulses to create an image? a. coded excitation b. harmonics c. pulse inversion d. rendering

a

which of thse statements regarding a bit of computer memory is false? a. its the smallest element of an image b. it is bistable c. eight bits combine to make a byte d. its s component of a digital scan converter

a

prior to display on an analog monitor, the digital information must be converted back to ______ form

analog

which scan converter was the first type that made gray scale imaging possible?

analog

what is a funnel shaped vacuum with an electron gun located within its smaller end that shot out electrons to contain image info?

analog scan converter

translating image info form the real world (analog) to the computer world (digital) and back again is a five step process. what does this process include? (pg 247)

analog to analog converter preprocessing postprocessing digital to analog converter video display

what is the first process to translate analog to digital? Electrical signals created by the transducer during reception from analog to digital form using this process

analog to digital converter

what is the fifth and final process used to translate analog to digital and back again? The signal, now in analog form is presented on this for interpretation

analog video display

the elastogram can be combined with what to add to diagnostic value of the exam?

anatomical image and doppler

traditional US pulses are very short and the energy within the pulse is highest around its main frequency. Typically short pulses provide superior _____ resolution; however, peak intensity is _______

axial, high

what is the primary storage device on a PACS system? a. magneto-optical storage b. hard disc drives c. solid state memory d. compact discs

b

what is the primary disadvantage of video tape and computer disc methods of image archiving? a. these methods are costly b. the info is vulnerable to erasure when exposed to strong magnetic fields c. only low resolution images are stored d. only black and white images are stored

b.

what is a group of bits and is simply a series of 0 and 1

binary number

________ images are composed of only 2 shades, black and white, and are high contrast

bistable

a bit is ______, having a value of either 0 or 1

bistable

What word is derived from the term binary digit, and is the smallest amount of computer memory?

bit

-computer memory -gray shades -contrast resolution these describe what?

bits

each pixel's shade of gray is determined by the cluster of _____ assigned to it

bits

What determines the brilliance of the displayed image?

brightness

what is a group of eith bits of computer memory, such as 10011111

byte

In modern elastography, how are the tissues deformed? A. by pressing the transducer into the skin B. with the use of a second probe C. automatically D. as a result of respiration

c

which of the following scan converters will provide the best spatial resolution? a. 256x256 pixels b. 512 x 512 pixels c. 1000 x 1000 pixels (pg 261)

c

which of the following statements regarding a pixel is false? a. it is the smallest part of a digital image b. a collection of bits, assigned to each pixel, stores the shade of gray c. it displays up to 3 gray shades simultaneously d. image quality is improved when the number of pixels is high

c

which of the following techniques is used to create image data where none really exists? a. edge enhancement b. temporal compounding c. fill- in interpolation d. spatial compounding (pg 264)

c

elastography has potential as a complementary tool for the diagnosis of what?

cancer

what is described as a sophisticated way of improving image quality?

code excitation

higher SNR improved axial resolution improved spatial resolution improved contrast resolution deeper penetration These are all advantages of what?

coded excitation

_________ _________ starts by acquiring multiple frames from different viewing angles. The frames are combined to form a single real time image

compound imaging

modern digital scan converters use __________ technology, whereas early scan converters were constructed from analog technology

computer

How are information and images stored in a PACS?

computer hard drives

converting info from analog to digital form is advantageous because digital info is far less susceptible to _______

contamination

What determines the range of brilliancies within the displayed image

contrast

with increasing number of bits per pixel, more shades of gray appear on the image. images with many gray shades have better ________ resolution

contrast

Two user controls on video monitors can alter characteristics of displayed images. what are they?

contrast and brightness

What is DICOM? A. Standards for transducer design B. Standards for patient exposure C. Protocols for two-dimensional imaging D. Protocols for medical image data

d

all of the following are advantages of PACS systems except a. data will not deteriorate over time b. images can be delivered to distant locations on the imaging network c. older, archived studies and reports can be reviewed easily d. images have higher resolution than what appears on the system's display

d

which electronic component is required for grayscale imaging? a. VCR b. non interlaced display c. computer memory d. scan converter

d

which of the following is not true about spatial compounding? a. data is collected from different viewing angles b. frame rates are reduced c. shadowing artifact can be eliminated d. can be performed with a mechanical transducer

d

The scan converter changes the format of what?

data

what numbers, which are used in everyday life, are based on ten choices, 0 through 9?

decimal numbers

The larger end of the analog scan converter's tube contains a __________ ________ or silicon wafer. The electrons strike the matrix where they are stored, then read to retrieve image info

dielectric matrix

are analog numbers or digital numbers binary?

digital

when using a _____ display device, step 4, digital to analog conversion, is unnecessary

digital

DICOM stands for what?

digital imaging and computers in medicine

what is the fourth process used to translate analog to digital and back again? Digital signals can't be directly displayed on analog display devices. The digital signals must be translated back to analog form using this fourth process

digital to analog converter

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

digitizing

Digital numbers are associated with computer devices and only have _______ _________

discrete values

The _______ is the essential link between the ultrasound system and the medical staff

display

The computer identifies and emphasizes sharp edge boundaries in the image, such as the reflecting surface between two media with different gray scale level. This describes what image processing method?

edge enhancement

what creates subtle bright and dark highlights on either sides of the edge boundaries to make them appear more defined?

edge enhancement

what is an image processing method that makes pictures look sharper?

edge enhancement

The stiffness data and Ultrasound reflections are combined into images called _________

elastograms

The theory of ______ is that tissues will deform differently following application of a force. Estimates of tissue stiffness are obtained

elastography

What is a dynamic technique that produces images form sound reflections in an entirely new way. Images are related to mechanical properties of tissue.

elastography

during reception, a transducer produces very low voltage electrical signals that ultimately create and image. These signals are so weak that they are susceptible to contamination by __________ ________

electrical noise

True or false. since postprocessing occurs after a-d conversion and storage, all the postprocessing changes can't be reversed

false

true or false. preprocessing doesn't alter the image and can be undone (pg 249)

false

fewer bits per pixel has what?

fewer shades of gray degrades contrast resolution

The goal of ______ ___________ is to fill in the gaps of the missing data in sector shaped images in a way that cannot be detected by the observer

fill-in interpolation

These newer display technologies are desirable since they provider higher ________ _______ with more ______ per image when compared to traditional televisions

frame rate, lines

the number of _______ and ______ angles varies, depending on the transducer characteristics and the clinical application with regards to spatial compounding

frames, steering

_______ compounding is an advanced technique that reduces speckle artifact and noise in ultrasound images

frequency

with ________ __________, the reflected signal is divided into sub-bands of limited frequencies, and an image is created from each sub-bands. The images from the sub-bands are then compounded into a single image

frequency compounding

with coded excitation, special mathematical techniques alter the long reflected pulses into a form suitable for a ______ quality image

high

What limitations make analog scan converters now obsolete? (pg 243)

image fade, image flicker, instability, deterioration

How do persistence and spatial compounding differ?

images used in persistence are from the same view spatial compounding are from different views

the coding of excitation shortens the pulse within the mathematical computation and _______ resolution

improves

Where does coded excitation occur?

in the pulser

edge enhancement works by ________ the image contrast in the area immediately around the edge

increasing

what is a method of constructing new simulated data point to fill in the gaps of sector shaped images

interpolation

coded excitation creates very ______ sound pulses containing a wide range of frequencies and distributes energy over a broad frequency range

long

With _________ , the sonographer can improve visualization of anatomic detail by enlarging a portion of the image.

magnification

elastogrpahy has been applied to differentiate what kind of lesions?

malignant from benign

with sector shaped images, gaps, or _______ data exist between the scan lines, especially as lines spread apart

missing

the _______ frames in the compound acquisition sequence, the better the compound image quality.

more

more bits per pixel has what

more shades of gray improved contrast resolution

PACS is the physical computer ______ DICOM is the set of rules that allows the components of the network to __________

network communicate

Modern flat panel computer monitors used advanced materials that create lightweight, thin displays. Flat panel displays have rendered traditional televisions virtually ___________

obsolete

With _______ a number of previous frames are superimposed on the most current frame. The display image contains "history" from earlier frames

persistence

what are synonyms for temporal compounding?

persistence, temporal averaging

what is the smallest building block of a digital picture?

pixel

what is the number of picture elements per inch?

pixel density

what are two important elements of digital scan converters?

pixel, bit

-image element -image detail -spatial resolution these describe what?

pixels

any alterations to a frozen image must be _______

postprocessing

any change after freeze time black/white inversion read magnificaiton contrast variation 3D rendering these all describe?

postprocessing

what is the manipulation of image data after storage in the scan converter?

postprocessing

what is the third process to translate analog to digital? The image information, still in digital form, continues to be process by the US system's computer. Any processing after storage in the digital scan converter is this third process

postprocessing

are the following procedures usually pre or post processing? a. modifying a frozen image b. read zoom c. write zoom d. adjusting the brightness on the monitor e. increasing the receiver gain

postprocessing postprocessing preprocessing postprocessing preprocessing

fill in interpolation is a form of _______

preprocessing

time gain compensation log compression write magnification persistence spatial compounding edge enhancement fill in interpolation these all describe

preprocessing

what is the manipulation of image data before storage in the scan converter?

preprocessing

what is the second process to translate analog to digital? The digital info is stored in the scan converter's computer memory and any processing of the reflected signals before storage is this second process.

preprocessing

persistence is less useful when imaging what kind of structures that can't be observed accurately?

rapidly moving

1. the ultrasound system scan the anatomy 2. The image is converted from analog to digital form and is stored in the scan converter 3. the sonographer identifies the ROI, and the system reads and displays only the original data that pertains to the region of interest. the ROI is not rescanned these 3 steps describe which kind of magnification?

read

Spatial resolution doesn't change because the number of pixels in the ROI is unchanged. however, the pixels are larger in the zoomed image. this characterizes what kind of magnification?

read

______ magnification occurs after the image data is stored in the scan converter.

read

_______ magnification can be used on a frozen image and is postprocessing

read

later, image data is ________ from the scan converter for display on the monitor

read

number of pixels or scan lines in the magnified image is the same as the original image characterizes what kind of magnification?

read

uses old data postprocessing larger pixel size same # of pixels as in original ROI unchanged spatial resolution unchanged temporal resolution these all describe which magnification?

read

what are two different forms of magnification?

read and write

The noise components of the reflections are different for each sub-band, and when combined, the noise level is _______

reduced

what are two limitations of compound imaging?

reduced frame rates and temporal resolution

Compound imaging _______ speckle and ________ shadowing artifacts

reduces, minimizes

what is a primar limitation of persitence

reduction in displayed frame, reduces temporal resolution

the selected part of the image when using magnification is known as the _______ ____ _________

region of interest ROI

The ________ __________ translates the information from the spoke format into the video format

scan converter

Gray scale imaging was initially made possible with the use of ______ __________, which first store information and later display it?

scan converters

with ________ shaped images, the scan lines separate at increasing depths

sector

persistence is most effective with what?

slowly moving structures

Higher pixel density is achieved with ____ pixels.

smaller

A _____ image with ______ noise, higher SNR, ______ image quality is produced when using persistence

smoother, reduced, improved

In elastography's early stages, the sonographer would press the transducer on the tissues to distort them. recent techniques no longer require this. Instead, the tissue deformation results from the force of what?

sound beam

what is a method of using sonographic info from several different imaging angles to produce a single image?

spatial compounding

The ________ ______, or image detail, of an analogy scan converter is excellent because of large number of storage elements within the matrix

spatial resolution

_________ ________ improves with high pixel density and creates and image with greater detail

spatial resolution

with fill-in interpolation, the line density increases, improving what?

spatial resolution

With write magnification _____ resolution may be improved if the bottom of the region of interest is shallower than the original image's depth of view

temporal

what is an image processing technique that continues to display info form older images?

temporal compounding

where does coded excitation take place?

the pulse

true or false. electronic steering of the sound beam is used in compound imaging. a technique only available with phased array transducers

true

List the advantages of digital scan converters (pg 243)

uniformity, stability, durability, speed, accuracy

Analog numbers numbers can have an unlimited and continuous range of ______ used in everyday life

values

a _____ of computer memory consists of two bytes, or 16 bits

word

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 US system then rescans only the region of interest and write s new data into the scan converter these four steps describe which type of magnification?

write

The increased number of pixels in the region of interest improves spatial resolution. the pixels are the same size in both the old and the zoomed image. This characterizes which kind of magnification?

write

______ magnification can't be used on a frozen image and is preprocessing

write

_______ magnification is applied during data acquisition, before storage in the scan converter.

write

acquires new data preprocessing identical pixel size more pixels than in the original ROI improved spatial resolution may improve temporal resolution these all describe which magnification?

write

the image used to identify the ROI is discarded and all new image info is acquired characterizes which kind of magnification?

write

the number of pixels or scan lines in ROI image is greater than that in the ROI's portion of the original image characterizes which kind of magnification?

write

Storage of the image info in the scan converted is called ?

writing

the data stored in the scan converter can be altered between the ______ and the ________ process

writing, reading

can the sonographer control postprocessing?

yes

can the sonographer control preprocessing.

yes

The image is stored in computer memory as a series of _____ and ______. The numerical representation of the image is processed then re-translated into an image displayed on a monitor

zeroes, ones


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