Understanding Ultrasound Physics
Chapter 12 Exam Questions and
Answers
Mechanical Transducer - ANSWER-- Disc shaped
- One active element
- Fan or sector shaped
- Crystal moves with motor
- Steered mechanically
- Fixed focusing
- No image when PZT is damaged
What is the channel a combination of? - ANSWER-Combination of the active element,
wire, and system electronics.
Types of Array Transducers - ANSWER-Linear
Annular
Convex
Linear - ANSWER-Active elements are arranged in a straight line
Annular - ANSWER-Elements are arranged as circular rings with a common center
Convex - ANSWER-Active elements are arranged in a bowed or arched line. The
transducer may also be called a curved, or a curviliner array.
Linear Phased Array - ANSWER-- compact with a small footprint
- 100 to 300 active elements on face
- square shaped
- No moving parts
- Steered and focused with phasing
- Adjustable focus (electronic focusing)
How many elements are excited in a phased array probe during a single sound pulse? -
ANSWER-All elements
What happens when the spike line is straight? - ANSWER-An unfocused sound beam is
created
What determines the direction the sound beam is steered? - ANSWER-The slope of the
electrical spike line
How is a focused beam created? - ANSWER-If the electrical pattern is curved
, What determines the depth of the focus? - ANSWER-Altering the electricity (changing
the curved pattern) coming from the beam former
What happens when the spike line is curved and has a slope? - ANSWER-It creates a
focused beam that is steered
What happens when the spike curve is curved outward or in a "D" shape? - ANSWER-
Defocused sound beam, has no application in diagnostic imaging
In Multifocusing three beams are created, what will the pattern with the greatest
curvature beam create, and the pattern with the least curve produce? - ANSWER-
Shallowest focus, and deepest focus
When the sonographer adjusts the focus what happens? - ANSWER-The curve
changes
With dynamic receive focusing, focusing may also occur during.... - ANSWER-
Reception
When the ultrasound system introduces time delays to some of the electrical signals
during the reception what happens? - ANSWER-A more accurate image can be created
As the transducer listens for reflections, what happens to the delay patterns during
receive-focusing? - ANSWER-They are continuously changing
Can the sonographer control the dynamic receive focusing? - ANSWER-No the system
does it automatically
Annular Phased Array - ANSWER-- Disc shaped elements
- Multiple rings with common centers (bulls eye)
- Image shape, sector or fan shaped
- Motor moving parts
- Mechanical steering
- Electrical focusing, multiple transmit focal zones
Linear Sequential Array - ANSWER-- Rectangular elements
- 120 to 250 rectangular shaped strips of PZT
- Image shape: rectangle
- No moving parts
- Steered electronically
- Fixed electrical focusing
Can linear sequential array transducers steer sound beams electronically? - ANSWER-
Yes. It creates a parallelogram shaped image instead of rectangle shaped
Chapter 12 Exam Questions and
Answers
Mechanical Transducer - ANSWER-- Disc shaped
- One active element
- Fan or sector shaped
- Crystal moves with motor
- Steered mechanically
- Fixed focusing
- No image when PZT is damaged
What is the channel a combination of? - ANSWER-Combination of the active element,
wire, and system electronics.
Types of Array Transducers - ANSWER-Linear
Annular
Convex
Linear - ANSWER-Active elements are arranged in a straight line
Annular - ANSWER-Elements are arranged as circular rings with a common center
Convex - ANSWER-Active elements are arranged in a bowed or arched line. The
transducer may also be called a curved, or a curviliner array.
Linear Phased Array - ANSWER-- compact with a small footprint
- 100 to 300 active elements on face
- square shaped
- No moving parts
- Steered and focused with phasing
- Adjustable focus (electronic focusing)
How many elements are excited in a phased array probe during a single sound pulse? -
ANSWER-All elements
What happens when the spike line is straight? - ANSWER-An unfocused sound beam is
created
What determines the direction the sound beam is steered? - ANSWER-The slope of the
electrical spike line
How is a focused beam created? - ANSWER-If the electrical pattern is curved
, What determines the depth of the focus? - ANSWER-Altering the electricity (changing
the curved pattern) coming from the beam former
What happens when the spike line is curved and has a slope? - ANSWER-It creates a
focused beam that is steered
What happens when the spike curve is curved outward or in a "D" shape? - ANSWER-
Defocused sound beam, has no application in diagnostic imaging
In Multifocusing three beams are created, what will the pattern with the greatest
curvature beam create, and the pattern with the least curve produce? - ANSWER-
Shallowest focus, and deepest focus
When the sonographer adjusts the focus what happens? - ANSWER-The curve
changes
With dynamic receive focusing, focusing may also occur during.... - ANSWER-
Reception
When the ultrasound system introduces time delays to some of the electrical signals
during the reception what happens? - ANSWER-A more accurate image can be created
As the transducer listens for reflections, what happens to the delay patterns during
receive-focusing? - ANSWER-They are continuously changing
Can the sonographer control the dynamic receive focusing? - ANSWER-No the system
does it automatically
Annular Phased Array - ANSWER-- Disc shaped elements
- Multiple rings with common centers (bulls eye)
- Image shape, sector or fan shaped
- Motor moving parts
- Mechanical steering
- Electrical focusing, multiple transmit focal zones
Linear Sequential Array - ANSWER-- Rectangular elements
- 120 to 250 rectangular shaped strips of PZT
- Image shape: rectangle
- No moving parts
- Steered electronically
- Fixed electrical focusing
Can linear sequential array transducers steer sound beams electronically? - ANSWER-
Yes. It creates a parallelogram shaped image instead of rectangle shaped
