Chapter 15

Question 1

bistable images are composed of only 2 shades ______ and ______ (high contrast)

Answer 1

black and white

Question 2

______ displays present multiple levels of brightness, the numerous levels allow the system to assign different gray shades to different echo amplitudes and to differentiate biologic tissues of different reflectivity

Answer 2

gray scale

Question 3

______ determines the range of brilliancies within the displayed image

Answer 3

contrast

Question 4

______ determines the brilliance of the displayed image

Answer 4

brightness

Question 5

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

Answer 5

scan converters (changes the format of data)

Question 6

the scan converter translates the information from the ______ format to the ______ format

Answer 6

spoke, video

Question 7

______ are “real world” numbers that are found in our everyday lives, they have an unlimited and continuous range of values

Answer 7

analog numbers (first type of can converter)

Question 8

______ are associated with computer devices, have only discrete values (limited choices)

Answer 8

digital numbers

Question 9

the analog scan converter is a ______ vacuum tube with an electron gun located within its smaller end, electrons contain information and shot out of the electron gun

Answer 9

funnel-shaped

Question 10

the ______ may be thought of as a picture divided into millions of tiny dots, each containing an electronic storage element, the storage element charges in each bucket are read to retrieve the image information

Answer 10

dielectric matrix (also known as silicon wafer)

Question 11

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

Answer 11

spatial resolution

Question 12

what are the limitations of analog converters?

Answer 12

image fade, image flicker, instability, and deterioration

Question 13

digital scan converters use computer technology to convert images into numbers, a process called ______, the images is stored as a series of zeros and ones, then processed and re-translated into an image

Answer 13

digitizing

Question 14

what are the advantages of digital scan converters?

Answer 14

uniformity, stability, durability, speed, and accuracy

Question 15

what are the 2 important elements of digital scan converters?

Answer 15

pixel and bit

Question 16

_____ (from the term picture element) is the smallest block of a digital picture

Answer 16

pixel- the entire pixel is a single shade of gray

Question 17

______ is the number of picture elements per inch

Answer 17

pixel density

high pixel density=smaller pixels, and more of them

Question 18

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

Answer 18

spatial resolution

Question 19

______ (from the term binary digit) is the smallest amount of computer memory

Answer 19

bit- has a value of either 1 or 0

Question 20

a ______ is a group of bits and is simply a series of 0’s ands 1’s

Answer 20

binary number

Question 21

______, which are used in everyday life, are based on ten choices, 0 though 9

Answer 21

decimal numbers

Question 22

a ______ is a group of 8 bits of computer memory, such as 10011111

Answer 22

byte

Question 23

a ______ of computer memory consists of 2 bytes, or 16 bits

Answer 23

word

Question 24

fewer shades of gray, degrades contrast resolution is?

Answer 24

fewer bits per pixel

Question 25

more shades of gray, improved contrast resolution

Answer 25

more bits per pixel

Question 26

How do you determine the number of gray shades that can be represented by a cluster of bits?

Answer 26

Multiply the number 2 by itself the same number of times there are bits

Question 27

What are the 5 steps in translating image information from real world (analog) to the computer world (digital) and back again?

Answer 27

1) analog-to-digital converter 2) the digital information is stored in the scan converter's memory 3) post processing 4) digital-to-analog converter 5) presented on analog video display

Question 28

______ is the manipulation of image data before storage in the scan converter, cannot be reversed or undone

Answer 28

Preprocessing

Question 29

______ is the manipulation of image data after storage in the scan converter (can be reversed)

Answer 29

Post processing

Question 30

TGC, log compression, white magnification, persistence, spatial compounding, edge enhancement, fill-in interpolation is?

Answer 30

Preprocessing

Question 31

Any change after freeze frame, black/white inversion, read magnification, contrast variation, and 3D rendering is?

Answer 31

Postprocessing

Question 32

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

Answer 32

Magnification

Question 33

What are the 2 forms of magnification?

Answer 33

Read and write

Question 34

_______ modification occurs after the image data is stored in the scan converter

Answer 34

read: 3 steps 1) US system scans anatomy 2) image is converted from analog to digital form and stored in the scan converter 3) the system reads and displays only the original data that pertains to the ROI

Question 35

what is read magnification characterized by?

Answer 35

- number of pixels or scan lines in the magnified image is the same as in the original image - spatial resolution does not change because the number of pixels in the pixel are larger in the zoomed image

Question 36

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

Answer 36

write; 4 steps 1) US 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) when the sonographer identifies ROI, the system discards all the existing data in the scan converter 4) the US system then rescans only the ROI and writes new data into the scan converter

Question 37

what is write magnification characterized by?

Answer 37

- the image used to identify the ROI is discarded and all new image information is acquired - the number os pixels or scan lines in the ROI image is greater than that in the ROI's portion of the original image - the increased number of pixels in the ROI improves spatial resolution

Question 38

uses old data, post processing, larger pixel size, same # of pixels as in the original ROI, unchanged spatial resolution, unchanged temporal resolution is?

Answer 38

read magnification

Question 39

acquired new data, preprocessing, identical pixel size, more pixels then in the original ROI, improves spatial resolution, and may improve temporal resolution is?

Answer 39

write magnification

Question 40

what does coded excitation provide?

Answer 40

higher signal-to-noise ratio, improves axial resolution, improves spatial resolution, improves contrast resolution, and deeper penetration

Question 41

______ is an sophisticated method of improving image quality, creates long sound pulses containing a wide range of frequencies and improves penetration results

Answer 41

code excitation; occurs in the pulser

Question 42

______ is a method of using sonographic information from several different imaging angles to produce a single image, starts by acquiring multiple frames from different viewing angles

Answer 42

spatial compounding; the more frames in the compound acquisition sequence, the better the compound image quality

Question 43

what does compound imaging do?

Answer 43

reduces speckle and minimized shadowing artifacts, reduced frame rates and temporal resolution is the limitation of this technique

Question 44

______ is an advanced technique that reduces speckle artifact and noise in US images, the reflected signal from the transducer is divided into sub-bands of limited frequencies, and an image is created from each sub-band (then combined into a single image)

Answer 44

frequency compounding

Question 45

______ is an image processing method that makes pictures look sharper, the computer identifies and emphasizes sharp edge boundaries in the image

Answer 45

edge enhancement

Question 46

edge enhancement creates subtle ______ and ______ highlights on either side of these boundaries to make them appear more defined, works by increasing the image contrast in the area immediately around the edge

Answer 46

bright and dark

Question 47

______, ______, or ______ is an image processing technique that continues to display information from older images

Answer 47

temporal compounding, persistence, or temporal averaging

Question 48

with ______, a number of pervious frames are superimposed on the most current frame (the display image contains history from earlier frames)

Answer 48

persistence; produces a smoother image with reduced noise, higher signal-to-noise ratio, and improved image quality

Question 49

what is the limitations of persistence?

Answer 49

a reduction in the displayed frame rate, which reduces temporal resolution; it is most effective with slowly moving structures and less with rapid moving structures

Question 50

all the images used in persistence are from the _____ view, the images used in spatial compounding are from ______ views or angles

Answer 50

same, different

Question 51

______ is a method of construction new simulated data points to fill in the gaps

Answer 51

interpolation- the goal of fill-in interpolation is to fill in the gaps of missing data in a way that cannot be detected by the observer

Question 52

fill-in interpolation is a form of prepocessing, the line density increased, improving ______

Answer 52

spatial resolution

Question 53

______ is a dynamic technique that produces images from sound reflections in an entirely new way, images are related to mechanical properties of tissue

Answer 53

elastography

Question 54

what is the theory of elastography?

Answer 54

tissue will deform differently following the application of a force, the tissue stiffness data and US reflections are combined into images called elastograms

Question 55

the tissues in elastography deformation results from the force of the sound beam itself, the elastogram can be combined with ______ images and _____ to add to the diagnostic value of the US exam

Answer 55

anatomical, doppler

Question 56

what is PACS (pictue archiving and communications system)?

Answer 56

describes the digital ultrasound laboratory in which images and additional medical information are digitized and stored on a large computer network

Question 57

what is DICOM (digital imaging and computer in medicine)?

Answer 57

it is a set of rules, or protocols, that allows imaging systems to share information on a network, when a particular US adheres to DICOM standards the system can successfully connect to a PACS medical information network