Two Dimensional Imaging

Question 1

What is Elevational Resolution also known as?

Answer 1

Slice Thickness, Volume Averaging

Elevational Resolution refers to the reflections on the image created from structures directly in the imaging plane or from structures that lie above or beneath the imaging plane.

Question 2

What type of transducer is best for Elevational Resolution?

Answer 2

Single, disc-shaped crystals found in Mechanical transducers

This configuration provides equal performance to Lateral resolution.

Question 3

Which type of transducer has the poorest Elevational Resolution?

Answer 3

Linear arrays

The rectangular shape of PZT in Linear arrays contributes to this disadvantage.

Question 4

How can poor Elevational Resolution from rectangular shaped PZTs be overcome?

Answer 4

By arranging multiple crystals in the up-and-down direction to focus the beam in the thickness plane

This arrangement may comprise of 700 total elements, 100 wide by 7 high.

Question 5

What is Rendering in ultrasound imaging?

Answer 5

Performed on a frozen image, creating an image from 3D data acquired during the ultrasound exam

Rendering adds elements of realism such as color and texture.

Question 6

What are Side Lobes in ultrasound imaging?

Answer 6

Some of the sound beam energy that spills from the main axis in the Far field, creating undesirable reflections

Side Lobes degrade Lateral resolution and are created by single element transducers.

Question 7

What are Grating Lobes?

Answer 7

Similar to side lobes, but created by Phased array transducers

Grating lobes occur all along the sound beam, reducing lateral resolution and degrading image quality.

Question 8

What is Apodization?

Answer 8

The most popular technique used to reduce side and grating lobes

Stronger electrical signals are used to excite the inner crystals, and progressively weaker electrical spikes excite the outer crystals.

Question 9

What is Subdicing in ultrasound technology?

Answer 9

A crystal is divided into a group of smaller crystals called sub-elements

These sub-elements are electrically joined and act as if they are a single crystal, which reduces grating lobes.

Question 10

What does Dynamic Aperture optimize?

Answer 10

Lateral resolution

It narrows a sound beam over a greater range of depths by changing the number of crystals used to transmit and receive sound beams.

Question 11

What is another name for Dynamic Aperture?

Answer 11

Variable aperture

This technique is used in ultrasound systems to optimize imaging.

Question 12

What does a Duplex Scanner display?

Answer 12

Doppler and 2D images

Duplex scanners are used for simultaneous imaging and Doppler analysis.

Question 13

What is a transducer?

Answer 13

A device that converts one form of energy into another.

Question 14

Define mechanical transducer.

Answer 14

A transducer that uses mechanical movement to generate images.

Question 15

What does ‘linear’ refer to in transducer types?

Answer 15

A transducer design where elements are arranged in a straight line.

Question 16

What is a linear phased array?

Answer 16

A type of transducer that uses multiple elements to steer beams electronically.

Question 17

What is an annular phased array?

Answer 17

A transducer made up of concentric rings for focusing sound beams.

Question 18

What are vector/virtual sector transducers?

Answer 18

Transducers that create images by combining elements from different shapes and steering them.

Question 19

Fill in the blank: A _______ array is characterized by a curved shape.

Answer 19

Convex/Curvilinear/Curved blunted sector

Question 20

List types of linear arrays.

Answer 20

• Linear Phased Array
• Convex Arrays
• Curvilinear Arrays

Question 21

What is the significance of slope in transducer design?

Answer 21

It affects the shape and direction of the ultrasound beam.

Question 22

What does ‘focusing technique’ refer to?

Answer 22

Methods used to concentrate the ultrasound beam for better resolution.

Question 23

Describe electronic focusing.

Answer 23

Focusing achieved by adjusting the timing of element firing electronically.

Question 24

True or False: Mechanical focusing can create a parallelogram-shaped image.

Answer 24

True.

Question 25

What is the effect of a malfunctioning active element?

Answer 25

Loss of entire image or dropout of image information.

Question 26

What is the typical shape of a sound beam?

Answer 26

Disc-shaped.

Question 27

Fill in the blank: A rectangular sound beam can be _______ wide.

Answer 27

1 wavelength wide

Question 28

What is the impact of erratic steering and focusing?

Answer 28

Variable effects on image quality, leading to dropout.

Question 29

What depth-related issue can occur with a malfunctioning crystal?

Answer 29

A horizontal band of dropout at a particular depth.

Question 30

Define transmit focusing.

Answer 30

Focusing achieved during the transmission of the ultrasound beam.

Question 31

What happens when a beam is steered to the right?

Answer 31

The ultrasound beam is directed towards the right side.

Question 32

What are the firing pattern time delays in phased arrays?

Answer 32

Separated by 10 nanoseconds.

Question 33

What is a common width for a compact footprint beam?

Answer 33

1 x 1 cm.

Question 34

What does the term ‘deeper focus’ refer to?

Answer 34

Achieving greater depth resolution in imaging.

Question 35

What does ‘shallow focus’ indicate?

Answer 35

Limited depth penetration and resolution.