Fundamentals of Invisible Sound Waves
Students taking the SPI need to look at what when evaluating graph measurements.
What is the x-axis.
The width of elements in a linear phased array transducer is this size.
What is 1/4 or about one quarter of a wavelength wide.
This is the maximum Doppler Shift obtained?
What is when the direction of sound travel is exactly opposite the flow direction.
These are the three types of artifact categories.
What is Propagation, Attenuation, And Doppler.
More complicated driving voltage-pulse forms are called this. Often patterns that include gaps are used.
What is coded excitation.
Explain the range equation and how it relates to the 13 microsecond rule.
What is to determine the distance from the source to the reflector. 6.5 microseconds are required for each cm of travel. 13 microseconds is the round trip time of the sound-echo travel. d=1/2 (0.77 x t)
Time delay generators can _______________ and ______________ the beam.
What is steering and focusing the beam.
This mathematical technique detected in the signal processor determines the mean and variance of the Doppler-shift signal.
What is autocorrelation.
This causes a Doppler-range ambiguity.
What is a high PRF.
The coding schemes for coded excitation are called this.
What are Barker codes.
Do higher or lower frequency transducers create a broader bandwidth?
What is shorter pulses, or higher frequencies.
A transducer that converts a rectangular image to a sector image is called this.
What is a vector transducer (phasing of a linear sequenced array).
Color-encoding the strength of the Doppler shifts which is free of aliasing and angle dependence is called this.
What is power Doppler.
This is caused whine the Doppler gain is set too high which overloads the amplifier.
What is cross-talk or leakage.
Pairs of transmitted pulses where the second pair is a bipolar sequence of the first.
What is Golay codes.
1/2 of intensity for every 1 cm of travel corresponds to this in attenuation coefficiency.
What is 3dB. Or What is a 3dB loss.
This type of detail resolution is decreased or degraded with long foci?
What is temporal resolution.
Doppler Shift voltages into separate forward and reverse channels is accomplished by this.
What is phase quadrature.
These two artifacts are tell tale signs of pathology.
What is enhancement and shadowing.
This technique presents qualitative or quantitative data of the stiffness, hardness, or softness of tissue.
What is Elatogrpahy.
Explain harmonic imaging (THI).
What is even and odd multiples of fundamental frequency.
Two-Dimensional arrays (3 or more rows of elements) can give rise to what resolution and artifact?
What is elevation resolution and slice (section) artifact. Example 1.5D T
This display can show spectral broadening in a shift spectrum?
What is the fast Fourier transform.
1/2 x PRF (kHz) equals this.
NL (kHz)
Name the sonographic instrucements of the machine.
What is the beam former, signal processor, image processor, and display.