# Shared Flashcard Set

## Details

DMS 235A Physics Midterm Review
N/A
88
Physics
Not Applicable
10/31/2009

Term
 Format using multiple pulses sent from one starting point that travel in the same direction, creating vertical parallel scan lines.
Definition
 Linear
Term
 Format using multiple pulses sent from the same starting point that travel in slightly different directions.
Definition
 Sector
Term
 Format using multiple pulses sent from different starting points along a curved line.
Definition
 Curved Linear
Term
 Measures the change in frequency of moving objects.
Definition
 Doppler Effect
Term
 Color doppler measures the _______ velocity of blood flow.
Definition
 mean or average
Term
 Spectral doppler measures the _______ velocity of blood flow.
Definition
 peak
Term
 Time for one cycle to occur.
Definition
 Period
Term
 Relationship between period and frequency.
Definition
 Reciprocals (inversely related)
Term
 Number of cycles that occur in one second.
Definition
 Frequency
Term
 Measurement of signal strength.
Definition
 Amplitude
Term
 Concentration of energy in a sound beam.
Definition
 Intensity
Term
 Part of the sound beam with the highest intensity.
Definition
 Focus (narrowest part)
Term
 Length of one complete cycle.
Definition
 Wavelength
Term
 The only parameter of waves determined by the medium and the source.
Definition
 Wavelength
Term
 Wavelength determines ______ resolution.
Definition
 Axial
Term
 The ________ the wavelength, the better the resolution.
Definition
 shorter
Term
 Wavelength is ___________ related to frequency.
Definition
 inversely
Term
 How to calculate wavelength.
Definition
 c/f or 1.54 mm per us/frequency
Term
 The distance sound waves travel through a medium in one second.
Definition
 Propagation speed
Term
 Propagation speed is fastest in _______, slowest in _____.
Definition
 solids; gas
Term
 The inability to be compressed.
Definition
 Stiffness
Term
 The relative weight of the volume of a material.
Definition
 Density
Term
 Stiffness is ________ related to the speed of sound.
Definition
 directly
Term
 Density is ________ related to the speed of sound.
Definition
 indirectly
Term
 Weakening of sound as it travels through a medium.
Definition
 Attenuation
Term
 Common measurement for electrical signal strength and brightness of images.
Definition
 decibel
Term
 3 Decibel Rule
Definition
 3 2.00 -3 0.506 4.00 -6 0.259 8.00 -9 0.12510 10.0 -10 0.10
Term
 Two things that determine attenuation.
Definition
 path length and frequency
Term
 Distance and frequency are ________ related to attenuation.
Definition
 directly
Term
 Three types of attenuation
Definition
 absorption, reflection, and scattering
Term
 Type of reflection in which sound is reflected off a smooth boundary in one direction.
Definition
 Specular
Term
 Three parts of a sound beam when it encounters an interface.
Definition
 Incident, reflected, and transmitted
Term
 Angle of incidence = ???
Definition
 Angle of reflection
Term
 When a wave reflects off an irregular surface and radiates in more than one direction.
Definition
 Diffuse (Backscatter) Reflection
Term
Definition
 Suboptimal angles can produce reflections back to the transducer
Term
Definition
 Lower strength than a specular reflector.
Term
 Images are best when the angle of incidence is __________ to the structure's surface.
Definition
 perpendicular
Term
 Type of scattering that occurs when the size of red blood cells are less than the wavelength.
Definition
 Rayleigh
Term
 Redirection of sound in many directions.
Definition
 Scattering
Term
 The number of decibels of attenuation that occurs when sound wave travels onecentimeter
Definition
 Attenuation Coefficient
Term
 Main form of attenuation in soft tissue.
Definition
 Absorption
Term
 How to calculate attenuation coefficient in soft tissue.
Definition
 dB = per MHZ x per cm x .5
Term
 The depth of tissue that results in 3dBof attenuation.
Definition
 Halve-Value Layer Thickness
Term
 The acoustic resistance to sound traveling in a medium.
Definition
 Impedance
Term
 Reflected intensity + Transmitted intensity = ???
Definition
 Incident intensity
Term
 What is the impedance formula?
Definition
 impedance = density x prop. speed
Term
 When transmission occurs at an obliques incidence and the wave becomes bent.
Definition
 Refraction
Term
 When the speed of medium 2 is GREATERthan the speed of medium 1 thetransmission angle will be _____ thanthe incident angle.
Definition
 greater
Term
 Time it takes for one pulse to occur.
Definition
 Pulse Duration
Term
 The distance or length a pulseoccupies in space from the start ofthe pulse to the end of the samepulse
Definition
 Spatial Pulse Length
Term
 How to calculate SPL.
Definition
 # cycles x wavelength
Term
 A ______ SPL improves image resolution.
Definition
 shorter
Term
 Pulse duration + one listening time
Definition
 Pulse Repetition Period
Term
 Number of pulses transmitted per second.
Definition
 Pulse Repetition Frequency
Term
 Percentage of time that pulsed ultrasound is transmitting (not listening).
Definition
 Duty Factor
Term
 Time it takes from the pulse creation to the pulse reception.
Definition
 Time of Flight or Go-Return Time
Term
 Time of flight is ______ related to depth.
Definition
 directly
Term
 What is the 13 microsecond rule?
Definition
 For every 13 microseconds of go-round time, the object is 1 cm deeper.
Term
 The property of a certain material to create a voltage when mechanically deformed.
Definition
 Piezoelectric effect
Term
 The property of certain material to change shape when voltage is applied to them.
Definition
 Reverse piezoelectric effect
Term
 Happens when the PZT material is heated above Curie temperature.
Definition
 Depolarization
Term
 Temperature at which PZT is polarized, or 365 degrees Celsius.
Definition
 Curie temperature
Term
 Located in front of crystal to insuretransmission of sound between crystal and skin.
Definition
 Matching Layer
Term
 Impedance of the matching layer must be between the impedance of the ___ and ____.
Definition
 PZT; skin
Term
 The matching layer is equal to _____ of the wavelength.
Definition
 1/4
Term
 Limits the ringing of the element.
Definition
 Damping or backing material
Term
 A characteristic of frequency: homogenity or pureness of the sound beam.
Definition
 Q-Factor (quality factor)
Term
 The _____ the q-factor, the better the image.
Definition
 lower
Term
 The range or difference between the highest and the lowest frequencies in the pulse.
Definition
 Bandwidth
Term
 The lower the Q-Factor, the _____ the bandwidth.
Definition
 wider
Term
 How to calculate Q-Factor.
Definition
 main frequency / bandwidth
Term
 CW transducer frequency is determined by?
Definition
 The frequency of the electrical signal.
Term
 PW transducer frequency is determined by?
Definition
 Thickness and speed of sound of PZT
Term
 Speed of sound of PZT and frequency of sound are _______ related.
Definition
 directly
Term
 Thickness and frequency are _________ related.
Definition
 inversely
Term
 Relationship between PZT diameter and focal depth.
Definition
 directly
Term
 Relationship between frequency and focal depth.
Definition
 directly
Term
 Relationship between wavelength and focal depth.
Definition
 indirectly
Term
 Crystal diameter and beam divergence are _________ related in unfocused discshaped element
Definition
 indirectly
Term
 Frequency and beam divergence are__________ related in unfocused discshaped element
Definition
 indirectly
Term
 A large active element may be thought of as millions of tiny, distinct, V-shaped sound sources (What principle is this?)
Definition
 Huygens'
Term
 Shape of a sound beam when wavelets interfere constructively?
Definition
 Hourglass
Term
 What happens to a sound beam when wavelets interfere destructively?
Definition
 Sound beam is absent.
Term
 Ability to distinctly identify 2 structures side by side or perpendicular to the beam
Definition
 Lateral Resolution
Term
 What improves axial and lateral resolution?
Definition
 high frequency
Term
 How does high frequency improve lateral resolution?
Definition
 narrow beam and less divergence
Term
 Correct number of reflectors but atimproper depth
Definition
 Range Ambiguity Artifact
Term
 Duplicate of true reflector (both real) and duplicate will be side by side at same depth
Definition
 lobe artifact
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