Describing Sound and Pulsed Waves
Resolution and Image Formation
Transducers and 2D Imaging
Artifacts
System Functions
100
Two sound waves that are in phase result in ________.
What is constructive interference?
100
This type of resolution is improved by using higher frequency transducers.
What is axial resolution?
100
This material reduces the "ringing" of the PZT.
What is backing material?
100
This common artifact appears as multiple equally spaced lines located parallel to the sound beam's main axis.
What is reverberation?
100
This part of the system is responsible for apodization.
What is the beamformer?
200
This is the number of cycles per second in a sound wave.
What is frequency?
200
This type of resolution improves with a smaller beam width.
What is lateral resolution?
200
This transducer type has many small disc-like elements. If a PZT is damaged, it will cause a horizontal band of drop-out on the image.
What is an annular phased array transducer?
200
This artifact is created when a sound pulse changes direction during transmission producing a second copy of the reflector side by side at the same depth of the true reflector.
What is refraction?
200
Part of the system that only function on transmission.
What is the pulser?
300
These two characteristics of a medium determine the speed of sound in that particular medium.
What are stiffness and density?
300
The relationship between crystal diameter and beam divergence in the far field.
What is inversely related?
Handicap won: 10 second delay to one team during Flash Formulas
300
A process that reduces the strength of side and grating lobes by altering the electrical spike voltage in the transducer.
What is apodization?
300
This is an example of this type of artifact.
What is mirror image?
300
Part of the receiver that controls the overall brightness of the image.
What is amplification?
400
This pulse wave parameter is the time from the start of a pulse to the start of the next pulse.
What is pulse repetition period?
400
This type of resolution is found in the 3rd dimension and is responsible for creating echoes within the GB.
What is elevational or slice thickness resolution?
400
This type of transducer works by firing groups of elements at one time to create a scan line.
What is a sequenced array transducer?
400
This artifact occurs when the attenuation rate is less than the surrounding tissue.
What is enhancement?
400
The sonographer controls the contrast of the image by adjusting this control on the machine.
What is dynamic range?
Handicap won: Team of choice cannot participate in one Headband slide.
500
This type of wave requires a medium to travel; it is how ultrasound propagates.
What is a mechanical wave.
500
This is the location of the sound beam where the beam diameter equals the diameter of the transducer in the far field.
What is two near zone lengths?
500
This type of transducer uses technology from both a phased and sequenced array and can create a trapezoid image.
What is a vector array transducer?
Handicap one: Only one person from the team can give clues to a teammate. Good for one Headband slide.
500
This artifact occurs when the insonification angle is close to 90 degrees in spectral Doppler?
What is crosstalk?
500
The sonographer controls the signal-to-noise ratio by increasing or decreasing the signal strength when adjusting this control.
What is power?