What is the name of the horizontal axis of a graph?
B. x-axis
Mega means
Millions
Hecto means
hundreds
Milli means
thousandths
Kilo means
thousands
Nano means
billionths
Giga means
billions
How can the volume of an irregularly shaped object be measured most accurately?
C. BY IMMERSING IT IN WATER
If you measure the amount of water that the object has displaced, you will get an accurate volume.
What term is used to describe the effects of an ultrasound wave on living tissues?
B. biological effects
US wave on LIVING TISSUES = biological effects
Which waves do NOT require a medium to propagate?
A. light
B. heat
C. sound
D. television
A, B, D.
Sound requires a medium to propagate.
Which describes the characteristic of a sound wave?
D. mechanical, longitudinal
Sound is best described as:
A. a series of compressions and rarefactions
Name the 3 acoustic variables:
Pressure, density, particle motion
Pressure can be represented in which units?
A. atmospheres (atm)
B. pascals (Pa)
C. millimeters of mercury (mm Hg)
D. pounds/sq inch (lb/in2)
ALL.
However, pressure of sound waves is most often reported in units of pascals.
Sound can be characterized as:
B. Sounds is a wave.
A wave is the rhythmical variation throughout time.
AIUM means:
American Institute of Ultrasound Medicine
Sound waves are:
D. longitudinal, mechanical
The speed of Us in soft tissue is closest to:
B. 1500 m/s
The frequency closest to the lower limit of US is:
A. 15,000 Hz
Which is NOT an acoustic variable?
C. INTENSITY
density, pressure, distance are acoustic variables
The effects of soft tissue on US are called:
B. acoustic propagation properties
____ is the time to complete one cycle.
C. period
Which of the following sound waves is ultrasonic and least useful in diagnostic imaging?
A. 30 KHz
____ is the distance covered by one cycle.
D. wavelength
Wavelength is the distance covered by one cycle.
Which is determined by the source and the medium?
A. range resolution.
Propagation Speed is equal to:
Frequency x Wavelength
P.S = FW
What is the rationale for the ALARA principle?
B. patient exposure
Propagation speed increases when:
Compressibility and density decrease
Units of PRF (pulse repetition frequency)
per minute
The time from the beginning of a pulse to the end is called:
A. pulse duration
What happens to the speed of sound in a medium when the bulk modulus of the medium increases?
B. faster
More stiffness = Faster
____ resolution is determined be the spatial pulse length.
B. axial
If a wave's amplitude is doubled, what happens to a power?
It is QUADRUPLED.
2A = 4P
Power of sound has units of:
WATTS
If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what has happened to the power?
C. halved
Intensity = Power/Area
I=P/A
Which intensity is the smallest?
A. SATA
The duty factor for continuous wave ultrasound is
B. 1.0
1 = duty factor for continuous wave us
What is the minimum value of the duty factor?
C. 0%
Minimum value of the duty factor = 0%
What are the units of intensity?
B. watts/cm squared
What happens to the speed of sound in a medium when the bulk modulus of the medium decreases?
C. slower
Speed of sound is SLOWER when bulk modulus DECREASES.
The units of attenuation are ____; this is a ____ scale.
C. dB, logarithmic
the units of attenuation are dB, this is a logarithmic scale
Sound intensity is decreased by 75%. How many decibels of attenuation is this?
B. 6dB = 75%
A pulse is emitted by a transducer and is traveling in soft tissue. The go-return time, or time-of-flight, of a sound pulse is 130 microsecs. What is the reflector depth?
E. 10cm
130microsecs / 10 = 10cm
If a 5MHz sound wave is traveling in the tissues listed below, which will have the shortest wavelength?
A. AIR
*****
If a 5MHz sound wave is traveling in the tissues listed below, which will have the longest wavelength?
C. bone
The approximate attenuation coefficient of 1MHz US in soft tissue equals:
0.5 dB/cm
1MHz = 0.5 dB attenuation coefficient
Rayl is the unit of:
IMPEDANCE
What are attenuations 3 components?
SCATTERING, ABSORPTION, REFLECTION
attenuation = SAR
Impedance is the product of:
propagation speed & density
For soft tissue, the approximate attenuation coefficient in dB/cm is equal to 1/2 frequency in MHz
The angle between an US pulse and the boundary between two media is 56degrees. This is called:
D. oblique incidence
Refraction only occurs if:
Oblique incidence & different propagation speeds
With 90degree incidence, reflections are always generated at a boundary if propagation speeds of the media are different. (T/F?)
FALSE
____ is a redirection of US in many directions as a result of a rough boundary between two media.
B. SCATTERING
What tissue most likely would create Rayleigh scattering?
RED BLOOD CELLS
With normal incidence the angle is 180degrees. (T/F?)
FALSE
Axial resolution is improved when spatial pulse length is DECRASED
Snell's law describes the physics of ____.
C. REFRACTION
snell's law refers to refraction
The most likely amount of reflection at a boundary between soft tissues is:
B. 1%
The most typical amount of transission at a boundary in biologic media is:
Nyquist frequency = the doppler frequency at which aliasing occurs
Doppler shift produces information about:
Velocity
The area of interrogation in a pulsed doppler exam is called:
Sample volume
What does velocity have that speed doesn't?
Direction. Speed only has magnitude, velocity has magnitude and direction.
What is the range of periods commonly found in waves produced by ultrasound systems?
C. 0.06 to 0.5 us
A wave with a frequency if 2 MHz has a period of 0.5 usec. A wave with a frewuency of 15 MHz has a period of 0.06 us.
With standard ultrasonic imaging, what happens to the period of a wave as it propagates?
B. remains the same
Period and frequency of a wave remain constant as sound wave propagates.
What determines the period of an ultrasound wave?
B. the transducer
Which of the following are appropriate to describe the period of an acoustic wave? (More than one can be correct)
A. minutes
B. microseconds
C. mm/us
D. cubic centimeters
A & B - minutes & microseconds
What term describes the number of cycles that an acoustic variable completes in a second?
A. Frequency - number of occurring events in a specific time
Which cannot be considered a unit of frequency?
B. cycles
The Doppler effect is presented as a ____ when the source and the receiver are ____.
Frequency shift; in motion relative to each other.
A sound beam is traveling from east to west. Blood is traveling from north to south. Which is true?
A. no Doppler shift
- This is normal incidence, there no Doppler shift with normal incidence.
Doppler shift provides formation about ____.
VELOCITY
At what angle between the sound beam and the direction of motion will the Doppler shift be a minimum?
90degrees. No Doppler frequency exists because the cosine of 90degrees is 0.
What are the current methods of processing spectral and color Doppler signals?
The FFT (FAST FOURIER TRANSFORM) method of spectral analysis for pulsed and CW.
Autocorrelation for color flow Doppler.
What is the typical range of Doppler Shift found in diagnostic imaging exams?
between 20 Hz and 20kHz. In the audible range.
The phenomenon where high velocities appear negative is called ____.
Aliasing.
The area of interrogation in a pulsed Doppler exam is called ____.
SAMPLE VOLUME
The higher the emitted frequency, the more likely a signal is to alias. (T/F?)
TRUE
The shallower the sample volume is, the more likely is a signal to alias. (T/F?)
FALSE
Only Pulsed wave Doppler exams have a sample volume. (T/F?)
TRUE
What feature does pulsed wave Doppler have that continuous wave Doppler does not?
RECIEVE GATE THAT IS ADJUSTED by the sonographer.
What is the recommended maximum angle of abduction?
A. 30 degrees
Using a tissue equivalent phantom, two pins at depths of 2 cm and 10 cm are imaged. On the systems display, you measure the distance between the two reflections created by these pins. What are you evaluating?
D. RANGE CALIBRATION
Using a tissue equivalent phantom, a sonographer adjusts the gain so that reflections on the display change from fully bright to barely visible. What is the sonographer evaluating?
D. SENSITIVITY
Which of the following phantoms can be used to evaluate performance Doppler systems?
C. STRING PHANTOM
Which best describes the interval at which quality assurance evaluations should be performed?
B. ROUTINELY
Which of these phantoms has similar attenuation peroperties as that of soft tissue?
C. tissue equivalent phantom
- the answer is in the question
Which agency collect sonographer injury data?
C. SDMS
Why is a tissue equivalent phantom used to interpret gray scale?
A. because sound attenuates
Which creates safety regulations for the workplace?
A. OSHA
OSHA - safety
Who is responsible for the quality assurance program in an ultrasound lab?
B. sonographer
When image is too bright or too dark use ALARA. What does ALARA stand for?
AS LOW AS REASONABLY ACHIEVABLE
How often should electrical safety checks be performed on a endocavitary transducer:
A. before each exam
Which has the lowest output power?
C. GRAY SCALE
Which creates the weakest reflection?
A. soft tissue - blood
Which creates the strongest reflection?
B. air-soft tissue
Identify one of the advantages of coded excitation:
D. PENETRATION
What is the meaning of a thermal index = 3 ?
B. tissue temperature may rise 3 degrees Celsius
The creation of an image by scanning from different angles best describes ____.
A. spatial compounding
You encounter a pt that does not speak english. Which is best to obtain informed consent?
A. call for a hospital interpreter
You enter a hospital room to perform an US exam. What do you do first?
D. politely check the wristband
Which of the following has the greatest output power?
C. pulsed Doppler has the greatest output power
Where does coded excitation originate?
C. THE PULSER
All of the following are true of normal cavitation EXCEPT:
B. harmful bioeffects are commonly observed
Identify one of the advantages of coded excitation:
A. improved contrast resolution
Which will eliminate range ambiguity artifact?
B. coded excitation
Which will eliminate range ambiguity artifact?
D. imaging deeper
Which will eliminate range ambiguity artifact?
A. lowering the PRF
What artifact is created by an object that is located deeper than the image?
C. range ambiguity
The consolidation of many images into a single frame best describes which of the following?
C. PERSISTENCE
With the presence of ____ we see more boundaries than there are reflecting surfaces.
B. REVERBERATIONS
What is another name for longitudinal resolution?
AXIAL RESOLUTION
What are the units of longitudinal resolution?
FEET
ft = long
Which is the best lateral resolution?
B. 0.06cm
If the spatial pulse length is 10mm, what is the axial resolution?
A. 0.5 cm
If the frequency is decreased, the numerical value of the radial resolution is _____.
INCREASED
A transducer CONVERTS one form of ENERGY into another.
The production of a voltage from the application of a pressure is called ____.
D. piezoelectricity
What is the production of deformation from voltage called?
D. piezoelectricity
Which is not a part of a transducer?
D. A/D converter
What is the Fraunhofer?
B. far zone
If we increase the frequency, the near zone length is:
C. increased
If the transducer aperature increases, the lateral resolution at its smallest dimension is:
C. INCREASED
If we increased the transducer diameter, the beam diameter in the far zone is:
C. DECREASED
At the focus, the beam diameter is ____ the transducer diameter.
D. half
The digital scan converter has a number of pixels assigned to each bit. (T/F?)
FALSE
Lateral resolution can be improved by:
FOCUSING
The more bits per pixel:
B. the more shades of gray
The more pixels per inch:
A. the better the spatial resolution
Which is the first adjustment made when an entire image is too dark?
A. GAIN
What is the elimination of voltages that do not exceed a certain level?
B. reject
What is the name of the receiver function that corrects for attenuation?
COMPENSATION
The process of changing gray scale is called:
DYNAMIC RANGE
Enhancement, multipath, and side lobes result in:
C. ARTIFACT
The propagation speed of the US in the AIUM test object is:
D. 1.54 mm/us
American Institute of US in Medicene
How many data bits are needed to represent 46 gray shades?
B. 6
The Fresnel is the:
A. NEAR ZONE
Which is associated with cavitation?
B. MECHANICAL INDEX
Which best describes the mechanistic approach to the study of bioeffects?
A. cause-effect
Which best describes the empirical approach to the study of bioeffects?
C. exposure-response
=empirical approach
Where are harmonics created?
A. in the tissues
How is range ambiguity artifact eliminated?
D. lower the PRF
For doppler, which incident angle results in no shift?
B. 90 degrees
90 degrees = no Doppler shift
Which transducer would be best to image superficial structures?
D. small diameter, high frequency
A transducer with more than one active element is called:
D. array
How many bits are needed to represent 16 shades of grey?
C. 4
What information does Doppler shift provide?
D. velocity
A sound wave is a pressure wave made of compressions and rarefactions. (T/F?)
TRUE
A hydrophone is used to measure:
INTENSITY & FREQUENCY
Images on a videotape are stored using:
D. COMPUTER MEMORY
Circumferences may be measured in unit of:
C. cm
Decimal uses a base of 10, binary uses a base of:
A. 2
If the frame rate increases and the lines per frame is unchanged, what else must happen?
B. depth decreases
Which cannot be performed by a sonographer?
A. clean pixels
Which is not a beam steering technique for a mechanical scanhead?
B. phased beam
Which has the greatest amount of attenuation?
B. bone
What is not the responsibility of the sonographer?
A. adjust the converter matrix
While scanning in a water tank, what location in a sound beam has the highest intensity?
D. focal point
Which of the following will result in the highest mechanical index?
D. low frequency and high signal amplitude
Which of these biologic tissues will sound waves propagate most quickly?
A. tendon
What is the standard for communication between medical imaging computers?
C. DICOM
The Curie Temp has what effect?
the ferroelectric material is depolarized
What happens to venous return to the heart during expiration?
C. decreased
PERCENT is NOT a unit
Pressure = Force/Area
Period (sec) x Frequency (Hz) = 1
inverse relationship, one goes up the other goes down
3 bigness parameters
API - amplitude, power, intensity
amplitude = dB, power = WATTS, Intensity = amplitude squared
I = P/A
INTENSITY (watts/cm2) = power (watts)/beam area (cm2)
Wavelength (mm) = 1.54 mm/us / frequency (MHz)
Speed and wavelength are DIRECTLY related
stiffness and speed = same direction
density and speed = opposite directions
compressibility and elasticity are opposites of stiffness
BULK MODULUS is the SAME as STIFFNESS.
bulk modulus increases, speed increases
If frequency of sound is doubled, what happens to wavelength?
Wavelength is halved
the effects of ultrasound upon tssue are called
BIOEFFECTS
Spatial Pulse Length (mm) = # of cycles x wavelength (mm)
Shorter pulses create higher quality images
PRF - pulse repetition frequency
PRF only determined by IMAGING DEPTH
PRF is NOT related to frequency
Duty factor is the percentage or fraction of the time the system transmits sound.
Max: 1.0 or 100%, continuous wave
Min: 0.0 or 0%, system is off
Shallow image = high duty factor
Deep image = low duty factor
SPTP = spatial peak, temporal peak - HIGHEST VALUE
SATP = spatial average, temporal peak
SPTA = spatial peak, temporal average *most relevant for thermal bioeffects*
SATA = sptial average, temporal average - lowest value
SPPA = spatial peak, pulse average
SAPA = spatial average, pulsed average
all have units of W/cm2 - they are all intensities
3dB = two times bigger
10dB = ten times bigger
-3dB = one half
-10dB = one tenth
IMPEDANCE = DENSITY x SPEED
Rayls represented by "Z" = density (kg/m3) x propagation speed (m/s)
Attenuation coefficient = amount of attenuation per centimeter
Units: dB/cm
frequency doubles, atten coef doubles
frequency doubles, Rayleigh scattering increases by factor of 16, (2x2x2x2=16)
Normal Incidence
"PORNN" = perpendicular, orthogonal, right angle, ninety degrees ALL MEAN THE SAME
if not at 90 degrees, it is oblique
Snell's law describes the physics of REFRACTION
Speed = distance/time
PZT is depolarized.
NEVER heat sterilize or autoclave transducers
Endocavitary probes require high level disinfection
never use a transducer with a cracked case, it can shock the patient
Quality factor is a unitless number related to the extent of damping
Low-Q = imaging pulsed transducers
High-Q = CW & therapeutic transducers
PZT crystal is half as thick, the sound frequency is twice as high
Low frequency = thick crystal, slow PZT
HIGH FREQUENCY = thin crystal, fast PZT
When a transducer is covered with a sterile cover with gel on the inside, what must the transducer avoid touching in order to create an image?
A. talcum powder
A sound beam is created by a round PZT crystal with a diameter of 10mm. The focal depth of the sound beam is 8cm. What is the diameter of the sound beam at a depth of 8cm?
D. 5mm
A sound beam is created by a round PZT crystal with a diameter of 10mm. The focal depth of the sound beam is 8cm. What is the diameter of the sound beam at a depth of 16cm?
A sonographer ajusts an ultrasound machine to double the depth of view from 5cm to 10cm. If the frane rate remains the same, which one of the following also changed?
B. narrower sector
A sonographer adjusts an image to change the sector size from 90 degrees to 45 degrees. Nothing else changes. The frame rate is:
A. doubled
A sonographer changes an images sector size from 90 degrees to 45 degrees. The frame rate remained unchanged. What else must have happened?
C. the line density was doubled
A sonographer using a phased array US system turns off the multifocus feature. What is the most likely consequence of this action?
D. the temporal resolution improves
A sonographer increases the line density from 1 line per degree of sector to 3 lines per degree of sector. What is the consequence of this action?
B. the temporal resolution decreases
Which will increase frame rate by a factor of three?
A. changing imaging depth from 21 to 7cm
Which of the following will have no effect upon temporal resolution?
B. increasing transducer frequency
What is the frame rate if each image of ultrasound system is created in 0.02 seconds (1/50th sec)?
D. 50 Hz
What is the time needed to make a single image if the frame rate of ultrasound system is 20 Hz?
A. 0.05s
What is the rationale for the ALARA principle?
D. patient exposure
Which of the following is associated with uniform amplification of signals?
D. gain
Which is associated with uniform brightness of an image?
A. compensation
All of the following are characteristics of contrast agents EXCEPT:
D. cost effective
An entire US image is too dark, but of uniform brightness. Which is the first adjustment that should be made to make the image brighter?
C. increase output power
An entire US image is too bright, but of uniform brightness. Which is the first adjustment that should be made to make the image darker?
C. decrease output power
Preamplification processes extremely weak signals that are susceptible to noise and often takes place in the transducer. (T/F?)
TRUE
With regard to ALARA, what is the best way to image deeper?
B. decrease transducer frequency
Which would have the shallowest delay on a TGC curve?
C. 5 MHz linear phased array transducer
How many Hertz is 3MHz?
A. 3,000,000
B. 3,000
C. 333
D. 0.003
Mega = MILLIONS
A. 3,000,000
Which would have the deepest delay on a TGC curve?
D. 2 MHz annular phased array transducer
How much bigger is a billion than a million?
B. 1,000
1 mil X 1,000 = 1 Billion
How many milliliters are contained in a jar filled with 5 liters of fluid?
