15 Image Processing + Dynamic Range Flashcards Preview

Ultrasound Physics > 15 Image Processing + Dynamic Range > Flashcards

Flashcards in 15 Image Processing + Dynamic Range Deck (19)
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1
Q

What is read magnification?

A

Does not rescan, only reads image in memory
Reads old data
Postprocessing
Same line density
LARGER pixels
Unchanged spatial and temporal resolution

2
Q

What is write magnification?

A
Rescans & acquires new data, discards old data
Writes new data
Preprocessing
Increased line density
MORE pixels
Improved spatial resolution
Temporal resolution can change
3
Q

What is fill-in interpolation?

A

Filling in gaps between lines

Preprocessing

4
Q

How does interpolation improve image detail (spatial resolution)?

A

Filling in missing data, especially for deeper parts of a sector-shaped image

5
Q

What is speckle?

A

Artifact that is grainy or granular appearance in tissues that are really homgenous

6
Q

How is speckle created?

A

Interference effects of scattered sound, both constructive & destructive, from many tiny tissue reflectors

7
Q

What is spatial compounding?

A

Scan lines are steered by the transducer in different directions or views and frames are averaged, improving signal-to-noise ratio

8
Q

What transducers have spatial compounding?

A

Phased array

9
Q

What is temporal compounding or persistence?

A

History of past frames that are overlaid or added on top of the current frame and averages previous frames producing a consolidation of past frames in the resulting image

10
Q

What is frequency compounding?

A

Creating an image by averaging frames obtained from different frequency sub-bands

11
Q

What type of compounding does not change temporal resolution?

A

Frequency compounding

12
Q

What is dynamic aperture?

A

Form of electronic receive focusing by varying the number of elements used to receive the reflected signal

13
Q

What is edge enhancement?

A

Increases the contrast at a boundary to make an image appear sharper

14
Q

What is coded excitation?

A

Long sound pulses that contain a complex pattern of frequencies and cycles - code
Occurs in the pulser

15
Q

What does coded excitation improve?

A

Penetration, axial resolution, spatial resolution and contrast resolution

16
Q

What is elastography?

A

Dynamic technique that produces images - elastograms, based on deformation when a force (sound pulse from transducer) is applied to tissue

17
Q

What is rendering?

A

Images with shadows, color, texture, and optical effects to create an element of realism

18
Q

What is dynamic range?

A
The ratio of the largest to the smallest signal strength that each component processes, the # of choices
# of gray shades in an image
19
Q

What are the different recording and archiving devices?

A

PACS - Picture Archiving and Communication System
DICOM - Digital Imaging and COmmunications in Medicine
NAS - network storage devices (high storage capacity disc drives, economical, used in PACS systems