Chapter 15
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
