Ultrasound Beams Flashcards
Describe the shape of the sound being as it travels away from the transducer.
It starts exactly the same width as the transducer diameter. The beam narrows progressively like a funnel until it reaches its smallest diameter. The beam then diverges and expands as it moves away from the source.
Define the near zone NZL.
The near zone is the area from the transducer to where the beam is exactly 1/2 the diameter of the transducer.
Defined the focal length
The distance from the transducer to the focus/focal point NZL
Define the focus or focal point.
The point at which the beam is one half the original diameter
To find the far zone.
The far zone is 2NZL where the beam expands to the original diameter of the transducer. NZL = FZL
Define the focal zone
The focal zone is the point slightly in front of and slightly behind the point where the beam is one half the original diameter.
What is the equation to determine the near zone length?
NZL = D2/4⋋
What factors determine the focal length?
Crystal diameter and transducer frequency.
What happens to the focal length when the Crystal diameter is larger?
There is a longer focal length.
What happens to the focal length when the Crystal diameter is smaller?
There is a shorter focal length.
How is the focal length affected by transducer frequency?
When the transducer frequency is higher there is a longer focal length.
Than the transducer frequency is lower, The focal length is shorter.
What are the factors of beam divergence?
Beam divergence is determined by diameter and frequency
How does Crystal diameter affect beam divergence
Beam divergence and Crystal diameter have an inverse relationship.
A larger Crystal produces less beam divergence.
A smaller Crystal produces greater beam divergence.
How does operating frequency affect beam divergence?
A higher frequency creates less beam divergence, in lower frequency creates more beam divergence. Again, Inverse relationship.
