ultrasound physics Terminology Flashcards

Terms Definitions
ten
deca
2
log of 100
Amplitude or intensity
Strength
quartzrochelle saltstourmaline
natural piezoelectric materials
Having 2 possible states
Bistable
AS FREQUENCY increases PERIOD_______.
DECREASES
25. B-mode display denotes:
a. basic motionb. beam motionc. brightness modulationd. basic reflection
Transducer frequency is directly proportional to:
a. period
b.wavelength
c. sound intensity
d. spatial pulse length
C
Having to do with sound
Acoustic
PHASED ARRAY MEANS:
"ADJUSTABLE" OR "MULTI-FOCUSING"
Wavelength
Distance to complete 1 cycle
meters per second
units of propagation speed?
15. Attenuation__________ , W/ increased path length
a. increasesb. remains the samec. decreasesd. disappears
The sonographer decreases the depth. Which of the following parameter is decreased: PRP, PRF, Resonance Freq, or non of tthem?
PRP
An artifiact produced by interference patterns and resulting in the granular appearance if images is termed what?
Speckle
Define B mode
Information displayed as brightness
Reflection with oblique incidence?
we don't know!!
12. Attenuation of 3dB corresponds to an intensity ratio of
a. 1.00
b. .50
c. .25
d. .33
e. .13
Transverse
wave which propagates by particle motion perpendicular to the wave propagation direction
With absorption, acoustic energy is converted into what?
Heat
Individual signal paths for reception and transmission of the sound beam are termed:
channels
Are the following pre or post-processing procedures: Increasing the receiver gain
Pre
Which operator control adjusts the dynamic range of the displayed echoes?
Compression
Media boundry that produces a reflection;reflecting surface
Reflector
The piesoelectric component of a transducer assembly
Element
Length of the focal region
Focal Zone
T/F
CONTINUOUS WAVE SOUND CANNOT BE USED TO MAKE ANATOMICAL IMAGES.
TRUE
WITH OBLIQUE INCIDENCE, INCIDENT INTENSITY=?
TRANSMITTED +REFLECTED
Z(rayls) = density(kg/m^3) x propagation speed(m/s)
equation for impedance
Time
Sec,ms,hours,or days
Period is reported in what units?
M-mode
In this display mode, the x-axis represents time and the y-axis represents depth.
28. The term which denotes the encounters of a pulse with scatterers at any point in its travels is
a. specular reflectionsb. backscattersc. speckled. contrast
Define Velocity.
Speed with direction of motion specified
Transducers are typically driven by how many cycles of alternating voltage for sonographic imaging?
1-3 cycles
Velocity
a vector quanity which implies both the rate and direction of movement.
The maximum cyclical change in a quantity is known as what?
Amplitude
At one half intensity depth:
a. the initial intensity equals zero
b. we are in the inatruments focal zone
c. the intial intensity was halved
d. beam divergence is minimum
C
Periodic evaluation of collected test data is termed:
quality assurance
An electronic method of reducing transducer ringing and improving axial resolution is termed what?
Dynamic damping
The difference between the transmit frequency and the received frequency is called what?
Doppler shift
Aliasing is a diagnostic parameter for severe disease.

True or False
False
What component of the US system converts the electric energy provided by the pulsar into acoustic pulses transmitted into the patient?
Transducer
How many gray shades can be represented by a group of 8bits, 4bits, or 2bits
8=256
4=128
2=64
What numbers represent binary numbers?
1's and 0's
Pressure difference divided by volume flow rate for steady flow
Resistance flow
Ability to distinghish echoes in terms of space,time or strength
Resolution
Reflection from a large,flat smooth boundry
Specular reflection
Array made of rectangular elements arranged in a line
Linear Array
CONCENTRATION OF FORCE WITH IN AN AREA?
PRESSURE
SOUND WITH FREQUENCIES LESS THAN 20Hz. SO LOW THAT IS NOT AUDIBLE.
INFRASOUND
THE ABILITY TO DISTINGUISH TWO STRUCTURES THAT ARE CLOSE TO EACH OTHER FRONT TO BACK, PARALLEL TO, OR ALONG THE BEAM'S AXIS.
AXIAL RESOLUTION
incident intensity(W/cm^2) = reflected + transmitted intensities
equation for incident intensity
When you have additional beams of significant intensity that travels out in some direction not included in the main beam, they are a source of artifacts?
Side lobes
What is Q factor?
The recriprical of fractional power
Define: Doppler frequency.
The difference between the transmitted and received frequencies
17. Which of the following has the slowest propagation speed
a. lung
b. soft tissue
c. fat
d. bone
Vacuum
the absence of a medium such as space
If the intensity of a signal is doubled, what is the affect on amplitude:
a. halved
b. quadrupled
c. doubled
d. squared
B
Formation of gas bubbles in soft tissue is a result of:
pressure changes
Which of the following imaging techniques utilizes pulse inversion:
A. real time imaging
B. harmonic imaging
C. panoramic imaging
D. multi-focal imaging
E. three-dimensional imaging
B. harmonic imaging
For nonfocused transducer, the region between the transducer element and the point at which the sound beam is narrowest is called what?
Near zone distance
Reflections from the blood are known as what?
Rayleigh scattering
What affect will increase the wavelength have on the spatial pulse length, it will?

a. increase SPL
b. decrease SPL
c. remain unchanged
d. depend on other parameters
a. increase SPL
Color aliasing is seen when red and blue colors are seperated by black.

True or False
False
Which of the following control should you adjust to improve the signal to noise ratio on the image: Dynamic range, Frame averaging, Gray scale map, Edge enhancement, receiver gain
Frame Averaging
Ultrasound produced in pulsed form by applying electric pulses or voltages of one or a few cycles to the transducer
Pulsed Ultrasound
A wave in which cycles repeat indefinitely;not pulsed
Continuous Wave
Device that allows only echos from a selected depth to pass
Gate
THE RATE THAT WORK IS PERFORMED, OR THE RATE OF ENERGY TRANSFER IS KNOWN AS:
POWER
THESE DESCRIBE THE FEATURES OF A PARTICULAR SOUND WAVE.
ACOUSTIC PARAMETERS
It affects penetration and image quality
Why is frequency important?
What is the typical range for pulse duration?
.5-3 microseconds
Define wavelength.
The length of space over which one cycle occurs
If a red blood cell is traveling ttoward a transducer, the frequency emitted by the transducer is what compared to the frequency reflected from the RBC?
Less than
Arrays are operated in which two ways?
1. Sequencing
2. Phasing
Wavelength depends on what two factors?
Frequency and propagation speed
In vivo, focal lesions will occur with intensities greater than:
10mW/cm2 SPTP
What type of transducer has the same measurement for elevational and lateral resolution?
Annular array
Which adjustment will not increase the frame rate? (choose the best answer)

a. dercreasing line density
b. decreasing depth
c. increasing line density
d. decreasing sector
c. increasing linedensity
intensity is determined by :

a. sound suource
b. medium
a. sound dource
You are performing a real time exam of the gall bladder. What mode of US display are you using?
B-Mode
Ability to image fine detail and to distinguish closely spaced reflectors
Detail resolution
THESE ARE KNOWN AS "THE EEFECTS OF THE MEDIUM UPON THE SOUND WAVE"
ACOUSTIC PROPAGATION PROPERTIES.
temporal average equals temporal peakSPTP=SPTA;SATP=SATA
In continuous waves _______ average equals temporal ________.So _______=_______, and ________=________.
far zone or Fraunhoffer zone
the region beyond the near field
Describe two types of pulse anatomy?
On time and listening time
Focusing can only be accomplished in what zone of a transducer?
Near-zone of a transducer
When you switch from a 2.5MHz to a 5MHz transducer, what happens to the wavelength?
It halves
Gain compensation is necessary due to:
attenuation of the sound beam
You are scanning the abdomen of an average sized 8yr old with a 3.5MHz Convex array probe. What comprimise are you making by selecting this probe?
Decreased spatial resolution
Refraction often causes a type of artifact known as

a. mirror imaging
b. edge enhancement
c. lateral position error
d. side lobes
c. lateral position error
If the pulse repitition frequency is increased, but no other paramenters are changes, what will occur?
Frame rate will increase
REFRACTION OCCURES WHEN TWO CONDITIONS ARE MET:
1. OBLIQUE INCIDENCE
2. DIFFERENT PROPAGATION SPEEDS
-10dB = 1/10 initial strength-20dB = 1/100 initial strength (initial x 1/10 x 1/10)
-10dB rule for negative numbers
What is the preferred or natural frequency for an element? Two names?
1. Operating Frequency2. Resonance Frequency
Medium 1 has a density of 9 and a stiffness of 6, Medium 2 has a density of 8 and a stiffness of 6. WHich medium has a lower prop speed?
Medium 1
For refraction we need to look for?
oblique incidence and different speeds
Frequency of the ultrasound wave is defined as what?
Number of cycles per second
Oblique incidence refers to:
an incident sound beam traveling at an oblique angle to the media
Electronic focusing in the transmit mode is accomplished how?
Time delays to excite crystal elements
What does the power spectrum depict?
Relative importance of each frequency in the doppler signal
Which of the following is the most reaspnable action to take when the image on your US system displays reflectors only in regions deeper than 5cm, but displays nothing from shallower depths: Adjust the systems compensation, Use higher frequency transducer
Adjust the systems compensation
WHAT IS THE EQUATION FOR SPL?
SPL= #OF CYCLES * WAVE LENGTH
What is constructed as a curved line of elements rather than a straight one? Two names?
1. Convex array2. Curved array
When creating an ultrasound image, all of the following assumptions are made Except which: Sound travels in a straight line, Sound travels at 1.54mm/microsec, Reflections only arise from structures in the pulses main beam, The sound beam is extremely thin
All structures create reflections of equal magnitude is false
What is the assumption # for Enhancement
Assumption #5 Intensity of the reflections is related to the scattering charateristics of the tissue (relates to shadowing and enhancement)
The digital memory of a scan converter:
A. accepts signals from the receiver
B. stores data as binary numbers
C. sends stored data to the display
D. changes received signals into numeric numbers
E. determines the brightness of the displayed echoes
B. stores data as binary numbers
What is the doppler frequency shift defined as?
The difference between the transmitted and recieved frequencies
You are scanning a patient with liver metastases and wish to improve contrast resolution to enhance the visibility of the lesion. You can accomplish this by: Increasing the acoustic output power, Decreasing the scan line density, Performing a read-zoom ov
Changing the gray-scale map assignment
MECHANNINCAL SCANNING, WHAT SHAPE IS THE PZT?
CIRCULAR AND DISC SHAPPED (LIKE A COIN)
Which of the following statements is true regarding axial resolution artifiacts: Higher quality images are associated with higher numbers, Axial resolution is reported in units of cm3, Numerically axial resolution equals 1/4 the pulse length, or Too few r
Too few reflectors appear on the image
What two conditions must be present to cause refraction of a sound wave?
Oblique incidence and different media propagation speeds
A waveform in the ICA obtained at a doppler angle of 45degrees shows aliasing, which of the following choices will NOT help you to unwrap this waveform: Increase the angle of incidence, Decrease the high pass filter, Lower the zero baseline, Increase the
Decrease the high pass filter
A transmitted wave is necesary for real time imaging, why?
Because the depth of the interface from which the echo originated can be determined
High frequency causes the beam in the far zone to diverge less, producing a narrower beam in the far zone.
Why does high frequency improve LATA resolution?
What is the region extending from the element out to a distance of one near-zone length? Name all three names?
1. Near zone
2. Near field
3. Fresnel zone
According to Snell's law, the angle of transmission is related to the incident beam angle and what?
The relative velocities of sound in the two media
What does the term signal to noise ratio denote?
The relative amplitude of the signal compared to the amplitude of the noise
THE CENTER FREQUENCY IN PULSED TXRS IS DETERMINED BY 2 CHARECTERISTICS OF THE CRYSTAL:
-THE THICKNESS
-THE PROP. SPEED OF THE PIEZOELECTRIC MATERIAL
You have increased the output power by 10dB. How much have you increased the signal intensity?
It is increased by a factor of 10
/ 120
Term:
Definition:
Definition:

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