Complete List of Terms and Definitions for Ultrasound Physics Review 4

Terms Definitions
Detection Demodulation
Diffuse to scatter about.
Tissue What is the medium?
Formula for intensity: power (watts)
---------------------
beam area (cm2)
Capability of doing work Energy
Power(W) / Area(cm²) Intensity = ?
To improve resolution, diagnostic tranducers are what? Focused
Lowering the doppler transmit frequency will provide increased penetration and will provide what type of reflected frequency shifts? Smaller
Number of cycles per second Frequency
IN-PHASE WAVES INTERFERE__________, WHILE OUT OF PHASE WAVES INTERFERE________. CONSTRUCTIVELY, DESTRUCTIVELY
medium only Speed is determined by what?
low Do pulsed wave imaging transducers have high or low Q-factor?
The sonographer increases the depth. Which parameter is decreased? PRF
What are the units of impedance? Rayls
What is the minimum doppler shift? .26(Khz)
3. As frequency increases, backscatter a. decreases
b. is not changed
c. increased
d. is refracted
Refraction SOund changes direction when it strikes a boundary:
1. Obliquely
2. When the media has different propagation speeds.

-Duplicate picture of the true reflector
-Duplicate pictures are placed side by side of the true anatomic structure.

Assumption #1 Sound travels in a straight line
What sound tissue interaction is necessary to form an ultrasound image? Reflection
Which testing device reflects amplitude received by the transducer: beam profiler
True or False: Spectral doppler displays flow direction turbulence and peak velocity information? True
Are the following pre or post-processing procedures: Modifying a frozen image? Post
Reduction in differences between small and large amplitudes. Region of high density and pressure in a compressional wave Compression
POWER ________ AS SOUND PROPAGATES THROUGH THE BODY. DECREASES
SHORTER PULSES PROVIDE BETTER _______ RESOLUTION? "LARRD"
Frequency The number of particular events that occurs in a specific duration of time
Inversely related How are frequency and period related?
How does a linear array fire? In succession
What is velocity determined by? Density and stiffness
3 components of attenuation: absorption, scattering and reflection.
Cross Talk Found only in DOPPLER!

Special form of mirror image where the doppler spectrum appears above and below the basline.

True unidirectional flow appears bidirectional, flow that should appear only on one side of the basline, incorrectly appears on both sides

Assumption # 2 Sound travels directly to a reflector and back to the transducer
During an ultrasound examination of the aorta, a 45degree beam to vessel angle would be called what? Oblique incidence
The following adjustment would decrease beam intensity: Increasing acoustic output, Decreasing receiver gain, increasing focusing, Increasing beam area, increasing amplitude Increasing beam area
Which testing device can produce retrograde flow: moving string
Varying the excitation voltage to each crystal in the group used to form the ultrasound pule is called what? Apodization
What parameter describes the axial lenght of the sample volume for a color pixel? Color gate
The half value layer and frequency have an inverse relationship.

True or False 		True
What control should you adjust to optimize the image if you are scanning a structure producing very bright echoes on the display: Rejection, TGC, Edge enhancement, Frame averaging, Freq TGC/DGC
Sound direction that is not perpindicular to media boundries Oblique incidence
Equalization of echo amplitude differences caused by different reflector depths Time gain compensation
Temperature at which an element material loses its piezoelectric properties Curie point
Sound scattered back in the direction from which it origanally came Backscatter
Single image produced by one complete scan of the sound beam Frame
THE _____ _____ DESCRIBES THE RELATIONSHIP OF BEAM INTENSITIES WITH RESPECT TO TIME. IT IS A UNITLESS NUMBER WITH A VALUE BETWEEN 0 AND 1. DUTY FACTOR
______ INTENSITY IS THE MOST RELEVANT INTENSITY WITH RESPECT TO TISSUE HEATING. SPTA
Destructive Interference The interference of a pair of out-of-phase waves results in the formation of a single wave of lesser amplitude than either of its components
piezoelectric effect the ability of certain materials to create an electrical voltage when they are mechanically deformed
10. How many cycles are their in a 2seconds of continuous-wave 5MHz U/S a. 5b. 10c. 5,000d. 5,000,000e. 10,000,000
What is the typical duty factor in pulsed echo? .1-1.0
The level at which signals are not transmitted through an ultrasound receiver is termed what? Rejection
If propagation speed 2 is ____ than propagation speed 1, then the transmission angle is less than the incident angle. less
20. Which of the following is the least obstacle to the transmission of U/S a. muscle
b. fat
c. bone
d. blood
Amplitude the amplitude of a physical quanity is defined as the strength,l volume, or size of that physical quanity. In more formal terms, the amplitude is defined as the max variation of a variable from its mean value. The units for the four acoustic variables represent amplitude, measurements. For the electrical variables, the unit of amplitude is volts.
As frenquency increases what else increasees? Absorption, Scattering, Attenuation
In unfocused transducer the focal length is determined by the:
A. beam diameter
B. penetration depth
C. element thickness
D. operating frequency
E. propagation speed of the medium 		A. beam diameter
Dynamic apodization is a method employed to do what? Reduce side lobes
True or False: Color dopppler has less velocity information than spectral doppler? True
True or False: Color doppler does not display mean frequency, direction of flow and turbulence False
The best quality images are obtained when there is what type of incident?

a. perpendicular
b. oblique 		a. perpendicular
All of the following decrease temporal resolution except: Lower frame rate, deeper imaging, multi focus imaging, or narrower sector Narrower sector
Ultrasound imaging in which pulses are reflected and used to produce a display pulse-echo technique
A b-mode image that represents an anatomic cross section through the scanning plan B scan
Change in frequency caused by motion of reflectors Doppler effect
Averaging if frames that view anatomy from different angles Spatial compounding
WHAT DOES SPPA STAND FOR? SPATIAL PEAK, PULSE AVERAGE.
WHAT ARE THE FIVE ADDITIONAL PARAMETERS OF PULSED ULTRASOUND? PULSE DURATION
PRP
PRF
DUTY FACTOR
SPL
sin(transmission angle)/sin(incident angle) = speed of medium 2/speed of medium 1If speed of medium 2 is less than medium 1, the angle of transmission will be less than the angle of incidence; if medium 2 is greater, the transmission angle will be greater What is Snell's Law?What does it mean?
focal zone the region where the beam is narrow and the image is relatively good
What are the 2 types of cavitation? Stable-dosent burst, Transient-Bursts
How are the maximum imaging depth and PRP related? Directly related
Speed of sound in soft tissue: 1.54 km/s
1540 m/s
1.54 mm/us
Hypoechoic Portions of an image that are not as bright as surrounding tissues, or tissues that appear less bright than normal.
Which of the followinf interactions of sound and tissue decreases the intensity of the transmitted beam? Absorption, Reflection, Scattering, Conversion to heat, or all of them? All of them
The testing used to collect data on the US system's performance is termed: quality control
Which of the following can not be evaluated with a tissue equvalent phantom: Axial resolution, Lateral resolution, Contrast resolution, Slice thickness, Temporal resolution Temporal resolution
What type of Doppler device uses two transducers, one to reeive and one to transmit? CW doppler
The type of mode which displays time versus motion is called:

a. A-mode
b. M-mode
c. B-mode
d. CDI 		b. M-mode
Which of the following would improve spatial resolution: Increasing transducer frequency, Increasing focusing, Decreasing PD, Increasing number of pixels on the display page, or all of them? All of them
Array that steers and focuses the beam electronically Phased array
WHAT IS THE AVERAGE SPEED OF ALL SOUND (REGAURDLESS OF FREQUENCY) IN BIOLOGIC OR "SOFT TISSUE" 1.54km/s=1,540m/s=1.54mm/us
WHAT ARE THE UNITS OF ATTENUATION? dB (MUST BE NEGATIVE)
Shorter wavelength sound produces higher quality images with greater detail. Why is wavelength important in diagnostic ultrasound?
What is the more complete name for linear array? Linear Sequenced Array
What does Duplex ultrasound mean? Ultrasound that combines gray scale with pulsed wave and continuous wave doppler
Propagation speed errors If the media through which the US travels doesn't propagate at 1.54 km/s then the assumed relationship between time and distance is invalid.

This results in:
1. Correct number of reflections on scan
2. Improper depths

Speed errors appear as a step off, split or cut

Assumption #3 Sound travels exactly 1,540 meters/second
Describe Diffuse reflection? A reflected beam that is scattered in all directions
The impedance formula and the unit is Z= velocity x density
Rayls
Power mode differes from color dopppler by evaluating what? The amplitude of the signal
The rate at which work is done is referred to as:

a. pressure
b. intensity
c. power
d. amplitude 		c. power
A sonographer adjusts an US machine to change the sector size from 90 to 45 degrees. Nothing else changes. What happens to the frame rate? It is unchanged
IN M-MODE:
X-AXIS - ??
Y-AXIS - ?? 		X- TIME

Y- REFLECTOR DEPTH
MEASURED BY PULSE'S TOF
WHAT IS THE EQUATION OF INTENSITY? POWER (watts) /
BEAM AREA (cm^2)
internal and external focusing What types of focusing are used with single-crystal transducers?
-10dB means the intensity was reduced how much? 10 times its original value
The rank of intensities from the largest to the smallest is: SPTP, IM, SPPA, SPTA, SATA
Focal Enhancement or
Banding 		Another form of enhancement within the forcal zone. This results from the increase in beam intensity found within the focal zone of a sound beam
1. Hyperechoic when compared to tissues above the beneath the enhanced region.

2. A bright stripe within the focal zone (side to side band)

Caused by Hyper focusing

Assumption # 5 Intensity of the reflections is related to the scattering charateristics of the tissues,
The imaging transducer exceeding the Curie point will result in: a loss of the piezoelectric properties
Which statement is not true regarding lateral resolution: It is equal to beam width, It is improved by focusing, It is defined as the minimum separation required to resolve two structures perpendicular to the beam axis, It is also known as the azimuthal r It remains constant throughout scanning depth
When ultrasound waves travel through a medium which contains many small scatterers, the amount of sound that is scattered would do what? Increase sharply with increasing frequency
The number of lines in the image is reffered to as:

a. frame rate
b. line density
c. dynamic range
d. PRF 		b. line density
If the PRF is increased to a level too great for the depth of field, what will the result be? Range ambiguity
CAN AXIAL RESOLUTIN BE CHANGED BY THE SONOGRAPHER? NO, TX IS NEEDED
frequency(MHz) = sound speed in PZT (mm/µs) / 2 x PZT thickness(mm) equation to determine frequency in pulsed wave transducers
What 2 variables determine the mediums properties? Stiffness-resistance of a material to compression, and Density-concentration of mass per unit of volume
Two Part QuestionWhat type of image does convex array produce? What is the complete name of convex array? 1. Sector Type
2. Convex sequenced array
Which of the following is an advantage of sub-dicing:
A. reduction of side lobes
B. increases the frame rate
C. reduction of grating lobes
D. increase in penetration depth
E. increase in temporal resolution 		C. reduction of grating lobes
What does dynamic receive focusing use? Delay lines after the echoes are detected in the array elements
Dynamic frequency tuning refers to which of the following?

a. the seperation of the fundemental and harmonic signals
b. a receiver function which adjusts automatically for attenuation due to depth
c. a process that changes the aperture of an array trance 		b. a receiver function which adjusts automatically for attenuation due to depth
Thin crystals; the thicker the crystal, the lower the frequency, and in diagnostic imaging one should use the highest frequency available while still being able to image at the depth of the area of interest. In diagnostic imaging, do we want to use transducers with thick or thin crystals?Why?
What is the assumption # for propagation speed errors? Assumption # 3 Sound travels exactly 1, 540 meters/ second
Reducing a 20dB amplifier by one-half will give a new gain setting of: 17dB

(3 dB reduction in a 20dB amplifier will give a new gain setting of 17 dB)
Which of the following is not an advantage of using SVHS video recorder on your US system: It demonstrates higher resolution in comparison to VHS, It can record in both SVHS and VHS formats, It has a separate color signal resulting in superior color defin It demonstrates higher resolution in comparison to VHS
THIS MAKES A SHORT PULSE WHICH MAKES A BETTER IMAGE. DAMPING ELEMENT OR BACKING MATERIAL
The Doppler shift does not always provide a valid estimate of the speed of the RBCs that produce it because the shit is related to what? The Cosine of the angle between the direction of the beam and the direction of blood flow
What is the assumption # for forcal enhancement or Banding? Assumption # 5 Intensity of the reflections is related to the scattering charateristics of the tissue (shadowing and enhancement)
You are using a linear array transducer to image a thyroid mass and would like to use a transducer in which the thinnest slice is close to the depth of the mass. Where is the thinnest width of the sound beam in the out-of-plane dimension? It is at the point of mechanical focusing
Which of the following can be considered an advantage of magneto-optical disk storage? The data can be erased and rewritten, A large volume of data can be stored on a single disk, Cine loops can be stored on the disk, MO disks are not susceptible to magnetic fields as regular disketts or digital tape
There are two causes of cross talk they are.... 1. Doppler reciever gain is set too high.

2.Incident angle near 90 degrees when flow is at focus