Dynamic Range

Question 1

What is Dynamic Range?

Answer 1

A method of reporting the extent to which signals vary and can still produce accurate images

Units: dB

Question 2

What does the term Threshold refer to in dynamic range?

Answer 2

Smallest signals that are accurately measured; minimum intensity which should be exceeded to get a certain change

Question 3

What happens to signals below the threshold?

Answer 3

They are too weak and will not be recognized by the system and are tossed out

Question 4

What is the Saturation Point?

Answer 4

Largest signals (max. intensity) that are accurately measured

Question 5

What occurs to signals above the saturation point?

Answer 5

They are too strong and are read as the max. intensity value

Question 6

How is Dynamic Range calculated?

Answer 6

(threshold) to (saturation point)

Question 7

Define Contrast Resolution.

Answer 7

Ability to distinguish the different/adjacent reflectors and still produce similar echoes

Question 8

What characterizes a Narrow Dynamic Range?

Answer 8

Limited choices; bistable (black and white)

High contrast

Question 9

What characterizes a Wide Dynamic Range?

Answer 9

Many choices; gray scale imaging (possible due to digital scan converter)

Low contrast

Question 10

What is Compression in the context of dynamic range?

Answer 10

Performed by the ultrasound machine to display the image; signal ranking remains the same, but the range is changed

Question 11

How can a sonographer adjust the dynamic range?

Answer 11

Via Gray Scale Mapping

Question 12

What are the components of an Ultrasound System?

Answer 12

Transducer, Receiver, Amplifier, Scan Converter, Display, Archive

Each component plays a vital role in the functioning of an ultrasound system.

Question 13

What does a narrow dynamic range refer to in ultrasound imaging?

Answer 13

Fewer Shades, Few choices, Black and white (bistable)

A narrow dynamic range limits the variety of grayscale in the images.

Question 14

What is the typical dynamic range of high contrast in ultrasound imaging?

Answer 14

100-120 dB

High contrast allows for better differentiation between various tissues.

Question 15

What is the formula for calculating the dynamic range of a compressed signal?

Answer 15

Uncompressed signal - amount of compression = dynamic range of compressed signal

This formula helps assess the impact of compression on signal quality.

Question 16

What does the term ‘low contrast resolution’ refer to?

Answer 16

60-100 dB

Low contrast resolution indicates a lower ability to distinguish between similar tissues.

Question 17

What is the mathematical relationship involving decibels in ultrasound?

Answer 17

Decibels add or subtract

This relationship is crucial for understanding how dynamic ranges are affected by compression.

Question 18

Fill in the blank: A dynamic range of _____ is considered low contrast.

Answer 18

40-50 dB

Low contrast ranges indicate limited differentiation in image quality.

Question 19

What is the dynamic range of images that is always less than the display?

Answer 19

10-20 dB

This indicates that the quality of the captured image may not fully utilize the display capabilities.

Question 20

What are the characteristics of a wide dynamic range in ultrasound?

Answer 20

More Shades, Many choices, Gray scale

A wide dynamic range enhances the ability to visualize subtle differences in tissue density.

Question 21

What does high contrast resolution indicate?

Answer 21

High contrast, Wide dynamic range

High contrast resolution is essential for accurate diagnosis based on imaging.

Question 22

What is the dynamic range for images that are low contrast?

Answer 22

20-30 dB

Low contrast images can make it difficult to differentiate between various tissues.

Question 23

What is the typical dynamic range for compressed signals?

Answer 23

10-30 dB

Compressed signals often result in a loss of detail and contrast.