Prepare for the ARDMS Sonography Principles and Instrumentation (SPI) exam with these practice questions and answers. This guide covers ultrasound physics, transducer technology, image artifacts, and Doppler principles.
Q: In soft tissue, if the frequency of a wave is increased the Propagation Speed (PS) will…
Answer: Remain the Same because stiffness and density affect Propagation Speed.
Q: What is the audible range?
Answer: 20-20,000Hz>20,000Hz=Ultrasound
Q: Frequency is measured in
Answer: Hertz (Hz)isCycles per SecondNot affected by sonographerIncrease Frequency; Decrease Depth
Q: A period is the length of time it takes for
Answer: one complete wavelength to pass a fixed point
Q: PRP is determined by
Answer: Transmit time and receive time.
Q: Period is measured in
Answer: Time (μs)
Q: When the sonographer changes the imaging depth what parameters are changed?
Answer: PRP, PRF, Duty Factor
Q: What is duty factor?
Answer: The percentage or fraction of time that the system is transmitting a pulse (Time Sound is ON or ON-Time).
Q: Propagation Speed in SOFT TISSUE
Answer: 1.54 mm/μs(1540 m/sec)
Q: Unit of measurement for Pulse Duration, Duty Factor, PRP, and Period
Answer: Time, (μs)
Q: Pulse duration is determined by
Answer: Sound Source Only
Q: Pulse Duration is controlled by
Answer: the ultrasound system and transducer
Q: Pulse Duration Formula
Answer: pulse duration (μs) = # cycles in pulse/frequency(MHz)PD= Number of cycles in Pulse/ Frequency(Hz)
Q: Spatial Pulse Length (SPL) (measurement)
Answer: The distance that a pulse occupies in space from the start to the end of a pulse.(mm)
Q: Typical values for spatial pulse length in soft tissue.
Answer: 0.1 to 1.0 mm
Q: Spatial pulse length is determined by
Answer: sound source and medium
Q: Spatial Pulse Length is directly proportional to
Answer: the Number of Cycles in the Pulseandthe Wavelength(Directly Proportional means that increased SPL will increase both the number of cycles in the pulse and the wavelength if increased).
Q: Spatial pulse length is inversely proportional to
Answer: Frequency (MHz)(Inversely Proportional means that increased SPL will lower frequency. This is because axial resolution is better with lower frequency)
Q: Pulse Duration (PD)
Answer: The actual time from the start of a pulse to the end of that pulse; a single transmit, talking, or “on” time.Time the pulse is on typically measured in (ms).
Q: Pulse Length
Answer: The distance of the pulse start to end or theduration or length of a single pulsePulse Length is typically measured in (mm).
Q: the ability of an object to resist compression and relates to the hardness of a medium?
Answer: Stiffness.Think:↑ Stiffness ↑ Speed↓ Density ↑ Speed
Q: An increase in pulse repetition frequency would lead to:
Answer: Increasing pulse repetition frequency, increases duty factor.↑ PRF ↑ Duty Factor
Q: Which of the following would have the highest propagation speed?
Answer: Bone has the highest propagation speed, at 2000-4000 m/s.
Q: What has the lowest propagation speed?
Answer: air technically has the lowest propagation speed at 300 m/s
Q: Which has the Slowest Propagation Speed?WaterSoft TissueBoneLung tissue
Answer: Lung Tissue
Q: As imaging depth increases, the pulse repetition frequency (PRF) must:
Answer: DecreaseAs imaging depth increase, pulse repeition freqency (PRF) decreases.↑ Imaging Depth ↓ PRF
Q: What describes the amount of refraction that occurs at an interface?
Answer: Snell’s lawRefraction: the redirection of the transmitted sound beamSnell’s law describes the angle of transmission at an interface based on the angle of incidence and the propagation speeds of the two media.
Q: Pressure is typically expressed in:
Answer: Pascals (Pa)
Q: The typical range of frequency for diagnostic ultrasound imaging is
Answer: 1-20 Mhz is the typical range of frequency for diagnostic ultrasound imaging.
Q: The attentuation coefficient in soft tissue is equal to:
Answer: Attentuation Coeffcient = 1/2 (one half of the frequency in soft tissue)The attentuation coeffcient (in dB/cm) is the rate at which sound is attentuated per unit depth.
Q: Micro is denoted as:
Answer: Micro is denoted as millionth (µ)
Q: What is described as the distance over which one cycle occurs?
Answer: Wavelength is distance over which one cycle occurs, or the distance from the beginning of one cycle to the end of the same cycle.Remember, it asks for distance over which one cycle occurs.
Q: Stiffness and propagation speed are
Answer: Directly RelatedAlso remember:↑ Stiffness ↑ Speed↓ Density ↑ Speed
Q: Areas of high pressure and density are referred to as:
Answer: Compressions
Q: What type of wave is sound?
Answer: Mechanical and Longitudinal Wave
Q: The frequency ranges for ultrasound are:
Answer: Ultrasound frequency is 20 to 20,000 Hz
Q: The speed of sound in soft tissue is
Answer: Speed of sound in soft tissue is 1540 m/s
Q: Which transducer fires the elements in groups?
Answer: Linear sequenced array fires the elements in groups
Q: The units for wavelength is
Answer: Wavelength units are (Millimeters)
Q: Enhancement is caused by
Answer: Weakly attenuating structures
Q: The wavelength in a material having a propagation speed of 1.5 mm/µs employing a transudcer frequency of 5.0 MHz is:
Answer: 0.3 mmwavelength = c/f1.5 mm/µs / 5 MHz = 0.3 mm
Q: An ultrasound transducer converts
Answer: Electrical energy into Mechanical energy and vice versa
Q: Lowest attenuation to highest
Answer: bone, muscle, fat, air
Q: If frequency doubles, what happens to the wavelength?
Answer: Wavelength is decreased by 1/2
Q: Frequency and Wavelength are:
Answer: Inversely related
Q: What happens to intensity if the amplitude of a signal is halved?
Answer: Amplitude halved will result in intensity quarteredamplitude = intensity2
Q: Ultrasound pulses contain a range of frequencies called
Answer: bandwidth
Q: How is time related to frequency
Answer: inversely
Q: What describes the percentage of time that sound is on?
Answer: Duty factor is the percentage of time the sound is being transmitted
Q: A 3 dB gain would indicate an increase in intensity by:
Answer: Two Times3 dB results in doubling of intensity (or power)
Q: The intensity of the ultraosund beam is usually greater at the focal zone because of
Answer: the smaller beam diameter
Q: Attenuation denotes
Answer: Progressive weakening of the sound beam as it travels
Q: Which of the following has the lowest intensity
Answer: SATA is the lowest of the intensities
Q: What is the definition of the beam uniformity ratio?
Answer: Beam Uniformity Ratio =Spatial peak / Spatial average
Q: Continuous wave Doppler has a duty factor of
Answer: 100%CW Doppler is always transmitting sound making it’s duty factor 100%
Q: The spatial pulse length is defined as:
Answer: the product of the wavelength and the number of cycles in a pulse?SPL = wavelength x cycles
Q: What term and philosophy relates the amount of exposure time for the sonographer and patient during a diagnostic ultrasound examination?
Answer: ALARA – As Low As Reasonably Achievable
Q: What term is defined as the body’s pathologic response to illness, trauma or severe physiologic or emotional stress?
Answer: Shock
Q: The inertia of the medium describes its:
Answer: Density.Inertia is described by Newton’s principle – an object at rest will stay at rest. An object in motion stays in motion, unless acted on by an outside force.
Q: Greatest attenuation would occur at:
Answer: long distance with high frequency
Q: A 3MHz sound beam travels through two media. It attenuates 5 dB in medium A and 6 dB in medium B.
Answer: Total attentuation is 11 dBAttenuation simply adds up as sound travels.
Q: What would you do to create a wave with the highest possible intensity?
Answer: Highest intensity would occur with a short distance and low frequency.
Q: Lowest Attenuation is found at
Answer: lowest frequency, with the shortest path length.
Q: What results in the most attenuation?
Answer: most attenuation occurs at the high frequency and long distance.
Q: Which media has the greatest attenuation and the slowest speed?
Answer: AirAir > Bone & Lung > Soft Tissue > Water
Q: What type of wave is sound?
Answer: Mechanical and Longitudinal wave
Q: The speed of sound in soft tissue:
Answer: 1540 m/s
Q: The unit for wavelength:
Answer: Distance (mm)
Q: Enhancement is caused by:
Answer: weakly attenuating structures
Q: Lowest attenuating to highest attenuation
Answer: Fat-Muscle-Bone-Air
Q: List propagation speed from lowest to highest
Answer: Air-Fat-Muscle-Bone
Q: Which of these media has the lowest attenuation and the greatest speed?bonetendonlungfatair
Answer: BoneAir > Bone & Lung > Soft Tissue > WaterBone is more stiff than air(remember ↑ stiffness, ↑ speed)
Q: What describes the physics of refraction mathematically?
Answer: Snell’s Law
Q: What is a reflection arising from a rough boundary?
Answer: Non-specularSpecular reflection is from a smooth reflector (like mirrors). They return in one direction.Whereas, non-specular is diffuse or scatter, reflection from a rough boundary.
Q: When time-of-flight is measured, we can determine the ________?
Answer: Reflector Depth
Q: A sound pulse travels from the transducer to location A, reflects off of it, and returns to the transducer in 130 μs.How deep is location A?
Answer: Location A is 10 cm from the transducerTotal travel distance would be 20 cm
Q: Which of the following would be considered the narrowest part of a sound beam?
Answer: The focus is the narrowest part of the beam
Q: Which of the following is the part of the transducer that stops the ringing of the element?
Answer: The damping material helps stop the ringing of the transducer
Q: Along with image depth, which of the following also determines the frame rate?
Answer: Image depth and the number of lines per frame determines the frame rate.
Q: Which type of resolution is an accurate representation of moving structures?
Answer: Temporal resolution, also known as frame rate, is the ability to display moving structures in real time.
Q: What type of transducer that utilizes elements arranged in a concentric pattern?
Answer: The annular array transducer ultilizes elements arranged in concentric rings
Q: What transducer would be considered an advantage of linear array over a phased array transducer?
Answer: The linear array has a wider near field of view compared to a phased array transducer
Q: Mechanical Transducers:
Answer: Have moving partsUses a motor to steer the beamMost transducers are no longer mechanical May be focused with a lens or phased focuses
Q: Along with crystal diameter, the divergence in the far field is also determined by…
Answer: Frequencyand crystal diameter determines the divergence in the far field
Q: What would cause an increase in frame rate?
Answer: Decreasing the imaging depthwould increase the frame rateWhen you decrease the imaging depth it can work faster (increase frame rate) because it doesn’t have to go as deep.
Q: The diameter of the beam in the Fresnel zone/near zone does what?
Answer: Decreases
Q: Which resolution is best in the clinical imaging?
Answer: Axial resolution is best in imaging
Q: will increase the near zone length?
Answer: A large crystal diameter with high frequency would increase the near zone length
Q: What will decrease beam divergence in the far field?
Answer: A large crystal diameter and high frequency would decrease the beam divergence in the far field
Q: Imaging transducers have
Answer: Imaging transducers have low quality factors and wide bandwidiths.
Q: What is the speed of a wave with a wavelength of 3 m and a frequency of .1 Hz?
Answer: 0.3 m/swave speed= frequency x wavelength
Q: Wavelength and Frequency are
Answer: inversely proportional to each other
Q: How do you calculate the speed of a wave given the wavelength and frequency?
Answer: Frequency (Hz) x wavelength (distance)= Wave Speed
Q: What is the speed of a wave with a frequency of 2 Hz and a wavelength of 87 m?
Answer: 174 m/s2Hz x 87m= 174m/sspeed of a wave: frequency x wavelength
Q: The ____ of a wave is the number of wavelengths that pass a fixed point in a second.
Answer: frequencyFrequency is the number of wavelengths that pass a fixed point in a second
Q: A sound wave is traveling in the body and propagates from muscle to air. What percentage of the sound wave is most likely reflected at the muscle-air boundary?
Answer: 75%
Q: Which of the following lists is in decreasing order?
Answer: Mega, kilo, deca, milli, nano
Q: The conversion of sound energy to heat
Answer: Absorption
Q: Acoustic Speckle
Answer: the interference pattern caused by scatterers that produces the granular appearance of tissue on a sonographic image
Q: Acoustic Variables
Answer: changes that occur within a medium as a result of sound traveling through that medium
Q: Amplitude
Answer: The maximum or minimum deviation of an acoustic variable from the average value of that variable; the strength of the reflector
Q: Attenuation
Answer: A decrease in the amplitude and intensity of the sound beam as sound travels through tissue.
Q: Attenuation Coefficient
Answer: The rate at which sound is attenuated per unit depth
Q: Axial Resolution
Answer: The ability to accurately identify reflectors that are arranged parallel to the ultrasound beam
Q: Backscatter
Answer: Scattered sound waves that make their way back to the transducer and produce an image on the display
Q: Beam Uniformity Ratio
Answer: The ratio of the center intensity to the average spatial intensity; also referred to as the SP/SA factor or beam uniformity coefficient
Q: Capacitive Micromachined Ultrasound Transducers
Answer: Technology used to create comparable transducer technology to piezoelectric materials
Q: Compression
Answer: An area in the sound wave of high pressure and density
Q: Continuous Wave
Answer: Sound that is continuously transmitted
Q: Damping
Answer: The process of reducing the number of cycles of each pulse in order to improve axial resolution
Q: Decibels
Answer: A unit that establishes a relationship or comparison between two values of power, intensity, or amplitude
Q: Density
Answer: Mass per unit volume
Q: Directly Related
Answer: Relationship that implies that if one variable decreases, the other also decreases or if one variable increases, the other also increases;also referred to as Directly Proportional
Q: Distance
Answer: How far apart objects areAKA vibration or displacement
Q: Duty Factor
Answer: The percentage of time that sound is actually being produced
Q: Elasticity
Answer: The ability of a material to bounce back after being disturbed
Q: Frequency (Hz)
Answer: The number of cycles per second
Q: Half-Intensity Depth
Answer: the depth at which sound has lost half of its intensity
Q: Half Intensity Depth is also called
Answer: Half-Value Layer Thickness
Q: Hertz (Hz)
Answer: A unit of frequency
Q: Hydrophone
Answer: a device used to measure the output intensity of the transducer
Q: Impedence
Answer: the resistance to the propagation of sound through a medium.
Q: Inertia
Answer: Newton’s principle that states that an object at rest stays at rest and an object in motion stays in motion, unless acted on by an outside force.
Q: Intensity
Answer: the power of a wave divided by the area over which it is spread; the energy per unit area
Q: Intensity Reflection Coefficient (IRC)
Answer: The percentage of sound reflected at an interface.The percentage of the sounds intensity that is reflected when sound hits a boundary or tissueInterface is the dividing line between 2 different media.
Q: Intensity Transmission Coefficient (ITC)
Answer: The percentage of sound transmitted at an interface-or-The percentage of intensity that continues forward after beam strikes an interface
Q: Interface
Answer: The dividing line between two different media
Q: Inversely Related
Answer: Relationship that implies that if one variable decreases, the other increases or if one variable increases, the other decreases; also referred to as inversely proportional
Q: Longitudinal Wave
Answer: Waves in which the molecules of the medium vibrate back and forth in the same direction that the waves are traveling.
Q: Medium
Answer: Any form of matter; Solid, Liquid, or Gas
Q: Non-specular Reflectors
Answer: Reflectors that are smaller than the wavelength of the incident beam
Q: Which gain will increase the risk of bioeffects?
Answer: Transmit
Q: What is considered the memory of an ultrasound instrument?
Answer: Digital Scan Converter
Q: Spectral Broadening Suggests
Answer: Turbulent Flow
Q: What happens to axial resolution with Pulse Wave Doppler
Answer: Axial Resolution Degrades when using Pulse Wave Doppler
Q: What color is usually used in Color Flow Doppler variance map to indicate turbulent flow?
Answer: Green
Q: A Doppler (high pass filter) eliminates?
Answer: high amplitude signals, low velocity flow
Q: The Doppler wall filter is considered a:
Answer: High Pass Filter
Q: The Nyquist Limit is equal to:
Answer: PRF/2Pulse Repetition Frequency divided by two
Q: Multiple echoes, equally spaced originating from a gas bubble is called
Answer: Ring Down
Q: An increase in red blood cell velocity will____________Doppler Shift:
Answer: Increaseincrease in rbc velocity increases Doppler shift
Q: The primary advantage of CW Doppler is:
Answer: Absence of Sampling Rate
Q: The range for ultrasound begins:
Answer: at 20,000Hz or 20KHz(Useful Frequency Range for Clinical Imaging is 2MHz-10MHz)
Q: Which instrument control affects the amplitude (db) of the outgoing signal?
Answer: Transmit Gain;Amplitude can be affected by the sonographer
Q: What is used to convert Doppler shift information into color?
Answer: Autocorrelation
Q: What is used to process conventional Doppler shift information but is too slow of a method for Color Doppler?
Answer: Fast Fourier transform
Q: Pulse Repetition Frequency
Answer: The number of pulses that an ultrasound system transmits into the body each second.Unit: Hz. Typically 4-15 KHz.PRF and Depth of View are inversely related.When the system is imaging deeper, the pulse repetition frequency is lower, as well as, the number of pulses created each second.
Q: What is the best way to increase the near field length of an ultrasound beam?
Answer: Increase Transducer Diameter
Q: What is the range of frequencies produced by a dampened PZT element?
Answer: bandwidth
Q: What is bandwidth?
Answer: range of frequencies in a pulse
Q: The percentage of time that the ultrasound instrument is emitting ultrasound is called?
Answer: Duty FactorThe maximum value is 1, the minimum is 0
Q: What is the unit of Duty Factor?
Answer: Duty Factor is Unit-lessIf the ultrasound is produced as a continuous wave (CW), the duty factor will have a value of 1. With Pulsed Wave the whole value of On-Time is fractioned.
Q: What is Q-factor or Quality Factor?
Answer: The “Q factor” describes the bandwidth of the sound emanating from a transducerTransducer Q Factor (Q = Quality) is associated with two characteristics of the crystal• purity of their sound and• length of time the sound persists(Unitless measurement)Fundamental Frequency(Hz)/Bandwidth(range of frequency in the pulse)
Q: The unit of duty factor is:
Answer: Unitless
Q: Clinical imaging transducers are:
Answer: Wide bandwidth; Low Q factorWide range of frequencies in the pulse and short period of time that the sound is emitted (pulsed wave)
Q: Power/Area=
Answer: Intensity
Q: Increasing wavelength will_______frequency?
Answer: Decrease
Q: Beam Properties
Answer: The ultrasound beam propagates as a longitudinal wave from the transducer surface into the propagation medium, and exhibits two distinct beam patterns: – a slightly converging beam out to a distance specified by the geometry and frequency of the transducer (the near field), and – a diverging beam beyond that point (the far field).
Q: Does Beam Width directly affect frame rate?
Answer: No:The following directly affect frame rate:Depth of PenetrationField of ViewNumber of Focusesand Line Density
Q: What affects frame rate?
Answer: Depth of Penetration, Field of View, Number of Focuses, and Line Density.Frame Rate= Number of Frames/Second
Q: When will a reflection occur at the boundary of two media?
Answer: If the acoustic impedances of the tow media are different.
Q: Snell’s Law
Answer: Describes the relationship between the angles and the velocities of the waves.When an ultrasonic wave passes through an interface between two materials at an oblique angle, and the materials have different indices of refraction, both reflected and refracted waves are producedIn ultrasound, Snell’s Lawis a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media.The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, for a given frequency.
Q: The Angle of Incidence
Answer: Refers to the angle of deviation from a perpendicular line to the surface of the tissueTherefore, the desired orthogonal(perpendicular) incident wave in ultrasound should be considered to have an angle of incidence of zero.When the angle of incidence is greater, fewer sound waves are reflected back to the transducer resulting in a more hypoechoic (darker) image with less clarity.The optimal reflection with the most sound waves occurs when the angle of incidence approaches zero and is virtually perpendicular (orthogonal) to the tissue of interest.
Q: Law of Reflection
Answer: the angle of incidence is equal to the angle of reflection
Q: Mechanical Transducers utilize what kind of focusing?
Answer: Fixed Focusing:Sonographers cannot determine the location of # of foci.Mechanical Transducers use Cross-Sectional imaging, rotating wheel, wobbler, and oscillating mirror.
Q: The transducer frequency is primarily determined by the transducer element’s what?
Answer: ThicknessFor pulsed transducers..the main or center frequency of the transducer is determined by the thickness and the propagation speed of the piezoelectric material.
Q: PZT is also called
Answer: Ceramic, Active Element, or Crystal
Q: A strongly focused transducer implies a:
Answer: Short focal length and Increased Beam Divergence
Q: B-mode displays reflector:
Answer: Amplitude and Distance
Q: An increase in the number of pixels on the display will improve:
Answer: Detail Resolution
Q: Propagation speed is determined by
Answer: Medium only – density and stiffness of mediaBulk Modulus describes the change in the material’s volume under external stress.
Q: Increasing transmit gain increases everything except:
Answer: FrequencyGain is a receiving function•Does not impact how much energy is transmitted to patient (i.e. power)
Q: The correct depth placement of reflectors depends primarily upon:
Answer: Propagation Speed
Q: What will increase the color flow jet area displayed?
Answer: Increasing Color Gain
Q: Increasing Propagation Speed
Answer: air: 330 m/secfat: 1450 m/secwater: 1480 m/secsoft tissue: 1540 m/secliver: 1550 m/seckidney: 1560 m/secblood: 1570 m/secmuscle: 1580 m/secbone: 4080 m/sec
Q: The most common type of transducer used in echo is:
Answer: Sector Phased Array
Q: What are the four acoustic variables?
Answer: 1. Temperature2. Density3. Particle Motion4. Pressure
Q: The Doppler effect is presented as a ___________________ when the source and the receiver are in motion relative to each other.
Answer: Frequency Shift
Q: + or – Doppler Shift
Answer: receiver toward the transducer= + shiftreceiver away from transducer = – shift+ toward (above baseline)- away (below baseline)