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Physics 2 > Chapter 15 > Flashcards

Chapter 15 Flashcards

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1
Q

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

A

black and white

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2
Q

______ 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

A

gray scale

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3
Q

______ determines the range of brilliancies within the displayed image

A

contrast

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4
Q

______ determines the brilliance of the displayed image

A

brightness

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5
Q

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

A

scan converters (changes the format of data)

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6
Q

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

A

spoke, video

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7
Q

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

A

analog numbers (first type of can converter)

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8
Q

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

A

digital numbers

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9
Q

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

A

funnel-shaped

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10
Q

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

A

dielectric matrix (also known as silicon wafer)

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11
Q

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

A

spatial resolution

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12
Q

what are the limitations of analog converters?

A

image fade, image flicker, instability, and deterioration

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13
Q

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

A

digitizing

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14
Q

what are the advantages of digital scan converters?

A

uniformity, stability, durability, speed, and accuracy

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15
Q

what are the 2 important elements of digital scan converters?

A

pixel and bit

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16
Q

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

A

pixel- the entire pixel is a single shade of gray

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17
Q

______ is the number of picture elements per inch

A

pixel density

high pixel density=smaller pixels, and more of them

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18
Q

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

A

spatial resolution

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19
Q

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

A

bit- has a value of either 1 or 0

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20
Q

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

A

binary number

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21
Q

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

A

decimal numbers

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22
Q

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

A

byte

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23
Q

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

A

word

24
Q

fewer shades of gray, degrades contrast resolution is?

A

fewer bits per pixel

25
Q

more shades of gray, improved contrast resolution

A

more bits per pixel

26
Q

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

A

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

27
Q

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

A

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

28
Q

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

A

Preprocessing

29
Q

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

A

Post processing

30
Q

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

A

Preprocessing

31
Q

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

A

Postprocessing

32
Q

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

A

Magnification

33
Q

What are the 2 forms of magnification?

A

Read and write

34
Q

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

A

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

35
Q

what is read magnification characterized by?

A
  • 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
36
Q

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

A

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

37
Q

what is write magnification characterized by?

A
  • 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
38
Q

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

A

read magnification

39
Q

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

A

write magnification

40
Q

what does coded excitation provide?

A

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

41
Q

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

A

code excitation; occurs in the pulser

42
Q

______ 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

A

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

43
Q

what does compound imaging do?

A

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

44
Q

______ 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)

A

frequency compounding

45
Q

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

A

edge enhancement

46
Q

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

A

bright and dark

47
Q

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

A

temporal compounding, persistence, or temporal averaging

48
Q

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

A

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

49
Q

what is the limitations of persistence?

A

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

50
Q

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

A

same, different

51
Q

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

A

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

52
Q

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

A

spatial resolution

53
Q

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

A

elastography

54
Q

what is the theory of elastography?

A

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

55
Q

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

A

anatomical, doppler

56
Q

what is PACS (pictue archiving and communications system)?

A

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

57
Q

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

A

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

Physics 2 (11 decks)

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