SPI Exam Pool Questions and answers. 100% Accurate, graded A+.

SPI Exam Pool Questions and answers. 100% Accurate, graded A+. What is described as the ability of an object to resist compression and relates to the hardness of a medium? - stiffness An increase in PRF would lead to - an increase in DF what has the higher propagation speed? air, bone, soft tissue or water - bone what has a lower propagation speed? water, soft tissue, bone or lung tissue - lung tissue as imaging depth increases, the PRF must - decrease what law describes the amount of refraction that occurs at an interface? - Snell's law pressure is typically expressed in - pascals the typical range of frequency for diagnostic ultrasound imaging is - 1 to 20 MHz the attenuation coefficient in soft tissue is equal to - one-half of the operating frequency micro denotes - millionth what is described as the distance over which one cycle occurs - wavelength what requires an oblique interface and a propagation speed mismatch - refraction areas of high pressure and density are referred to as - compressions spl can be calculated by - multiplying the number of cycles by the wavelength density is typically measured in - Kilograms per centimeter cubed as a sound wave travels through the human body, the intensity of the sound wave decreases as a result of - attenuation what is the total attenuation that occurs if a 6 MHz sound beam travels through 4 cm of soft tissue - 12 dB, attenuation= f/2 * pL as imaging depth increases, PRP - increases what are the units of df - unitless the percentage of time that the ultrasound system is producing pulses of ultrasound describes the - df density and propagation speed are - inversely related what is determined by the sound source and medium - wavelength what is defined as the number of ultrasound pulses emitted in 1 second - prf what is defined as only the active time - pd the intertia of the medium describes its - density what is determined by the sound source only - frequency if the angle of incidence is 40 degrees, what is the angle of transmission at the interface if medium 1 has a propagation speed of 1320 m/s and medium 2 has a propagation speed of 1700 m/s - less than 40 degrees the change in the direction of the original sound wave that occurs when sound interacts with two different tissue types that have a different propagation speed is - refraction which of the following is an appropriate unit of measurement for propagation speed - millimeters per microsecond the major component of attenuation is: - absorption in clinical imaging, the wavelength typically measures between - .1 to .8 mm the df for cw ultrasound is - 100% what is the change in intensity if the power decreases by half - intensity is halved damping of the sound beam - reduces the spl adding damping to the transducer improves which type of resolution - axial what time is defined as the beginning of one pulse to the beginning of the next pulse and, therefore, includes both the "on" and "off" time - prp what are the units for pressure - pascals or pounds per square inch what term is defines as "the power of a wave divided by the area over which the power is distributed" - intensity transducers have material within them that, when electronically stimulated, produces ultrasound waves. This is most likely some form of: - lead zirconate titanate what is the change in power if the amplitude triples - it increases nine times the portion of the sound beam where the molecules are farther apart describes an area of - rarefraction if only the density of a medium is increased, then the - propagation speed will decrease sound is technically a - mechanical and longitudinal wave the maximum value or minimum value of an acoustic variable minus the equilibrium value of that variable describes the - amplitude what is the speed of sound in soft tissue - 1540 m/s what is considered the narrowest part of a sound beam - focal zone what part of the transducer stops the ringing of the element - damping material along with image depth, what also determines frame rate - number of lines per frame which type of resolution is an accurate representation of moving structures - temporal resolution if the depth is increased and the frame rate is unchanged, what must have decreased - the number of lines per frame what transducer can be described as having the scan lines originate from a common point of origin - sector array along with crystal diameter (aperture), what is the divergence in the far field also determined by - frequency what would cause a decrease in temporal resolution - increased line density what would cause an increase in frame rate - increased PRF what is true of the diameter of the sound beam in the fresnel zone - it decreases with distance from the transducer which resolution typically has the lowest number in clinical imaging - longitudinal what would most likely increase the near-zone length - large crystal diameter, high frequency what would most likely decrease beam divergence in the far field - large crystal diameter, high frequency imaging transducers typically have - low-quality factors, wide bandwidths what does damping material produce - decreased sensitivity, wide bandwidths, low-quality factors what electrical pattern produces electronic focusing of the ultrasound beam - curved in an unfocused, single-element transducer, the width at the focal point of the sound beam measures how much compared to the beam width at the fact of the transducer - one-half what facilitates the transmission of sound from the element into the patient's skin - matching layer what describes the range of frequencies present within the beam - bandwidth which type of interference results in higher-amplitude sound waves - constructive interference what affects temporal resolution - line density, image depth, number of focal zones what are the components of the damping material - epoxy resin loaded with tungsten what are synonyms for axial resolution - range, depth, radial what does temporal resolution relate to - frame rate what is referred to as the far zone - fraunhofer zone what states that waves are the result of the interference of many wavelets produced at the face of the transducer - Huygen's principle what is the resolution in the third dimension of the beam - elevational what is the relationship between the frequency and the near zone - the higher the frequency, the longer the near-zone length what is defined as changing the timing of the shocking elements in order to shape and steer the beam - phasing what are the components of spatial resolution - contrast, axial, elevational which transducer has no range resolution - continuous-wave what transducer is not used for imaging - continuous-wave what transducer is also referred to as a sector or vector transducer - phased-array what shortens the length of the pulse by decreasing the number of cycles in the pulse - backing material what produces a pie-shaped image - phased array the portion of the transducer that comes in contact with the patient is the: - matching layer what does heat sterilization do to an ultrasound transducer - kills pathogens and destroys the transducer what is the minimum distance two reflectors can be, parallel to the beam, and still appear on the screen as two dots - range resolution what describes the result of destructive interference - the resulting wave is much smaller than the original wave to produce a transducer with a higher frequency one should - use a thinner piezoelectric element what would be best utilized for imaging of deep structures in the abdomen - curved sequenced array transducer what is the equation for frame rate - frame rate is equal to the pulse repetition frequency divided by the lines per frame what is represented as time, or the ability to display structures in real time - temporal resolution how are ultrasound transducers typically steralized - cold-sterilization methods the output gain of the pulser determines the _______ of the acoustic pulse. - intensity what is the function of the receiver that changes the brightness of the echo amplitudes to adjust for attenuation with depth? - compensation what task is incorporated in the process of demodulation - rectification what is the smallest element in a digital picture called - pixel what is the name for the smallest amount of digital storage - bit what receiver function converts the negative portion of the signal to positive - rectification a video display that is limited to only black and white, no other shades of gray, is called - bistable what type of display uses a backlight with two polarized filters to produce an image - LCD in tissue harmonic imaging, what frequency is used to produce the image - double the fundamental frequency what backup system is used to protect stored data on a PACS - RAID array with 6 bits, what is the largest number of different shades of gray that can be stored - 64 (2^n) in b-mode imaging, the stronger the return echo - the brighter the dot on the display what happens to a digital image when the pixel density is increased - there is more spatial detail you are using a transducer that produces a beam with a very wide elevational plane. What problem are you most likely to encounter as a result - slice thickness artifact the "useful" artifact you might see behind a weakly attenuating structure is - enhancement when you adjust the output power control, you affect the following system component - pulser the part of the receiver that reduces low-level system noise is - rejection what receiver function is responsible for decreasing the difference between the largest and smallest received signal amplitudes - compression sound bouncing off a strong reflector and producing an image on the wrong location on the display is - mirror image artifact what must be known in order to calculate distance to a reflector - travel time and speed (distance = rate x time) contrast resolution is - the ability to see differences in shades of gray what happens after the image has been frozen - postprocessing in which mode is the strength of the reflector represented by the brightness of the dot - B-mode which mode is interested in the movement of the reflectors along one scan line - M-mode in M-mode imaging, what is along the x-axis - time the harmonic signal is produced by - the patient what imaging in tissue harmonic imaging - the fundamental frequency is filtered out a sound wave travels 26 us to a reflector. how far away is the reflector, assuming the medium is soft tissue - 4 cm (d=.77t) a reflector is 20 mm away from the transducer. how long does it take for sound to travel to the reflector and back - 26 us (t=d/.77) what technique is used to reduce the presence of grating lobes - subdicing the strength of the voltages sent to each element is determined by the - beam former an advantage of coded excitation is improved - signal-to-noise ratio if the far field of the image is too dark, it is recommended that you - increase the receiver gain read zoom is a function of the - postprocessing which type of zoom offers a high-quality zoom but must be selected while the image is live - write zoom as the sound beam travels, it is attenuated. this explains the need to have which receiver function - compensation the smallest component of a 3D image is the - voxel the technique that uses made-up pixel information to replace areas between the scan lines where there is no actual signal information is - fill-in interpolation what is the standard for data exchange among imaging systems - DICOM an artifact that occurs when a sound beam bounces back and forth between two strong reflectors, creating a "stepladder"-like appearance is - reverberation additional reflectors on the screen (with an array transducer) that are from extraneous sound waves off the primary axis of the beam are - grating lobes sound travels through a large quantity of muscle tissue. the reflector will be displayed - too close to the transducer a shadow occurs when sound - travels through an area of increased attenuation the echo information is taken from the memory and sent to the _____ so it can be shown on the display - D-to-A converter which older mode may still be used today in ophthalmology - a-mode which part of the ultrasound machine does not affect the amount of energy entering the patient - receiver an image with one bit of memory has how many shades of gray - two the part of the machine responsible for timing the reception of pulses to determine their location is the - master synchronizer a technique that averages out the frequencies used to make the image to improve contrast resolution and reduce speckle is - frequency compounding artifacts related to propagation speed occur because - the machine assumes 1540 m/s for all tissue what provides the potential energy in the cardiovascular system - beating heart which type of color scale displays turbulence as a shade of green - variance what is the name of the flat flow profile that is seen at the entrance of vessels - plug flow what does increasing the PRF/scale setting on a spectral doppler do - decreases the potential of aliasing what is seen with CW instrumentation - transducer frequency matches that of the oscillator when is the doppler shift the highest - when the beam is parallel to the direction of flow what will eliminate aliasing - increasing the PRF, increasing the nyquist limit above the frequency shift, decreasing the sample depth when a reflector moves toward the transducer, what will happen to the reflected frequency - increase what has to be increased in order to see an increase in flow volume - pressure difference adjusting what will have no effect on the measured frequency shift - amplitude what is the equation for Ohm's law - V=IR what is the point at which reynolds number predicts turbulence - 2,000 in order to maintain volume flow as a constant, if the area of a vessel increases what must happen to the velocity - it decreases venous blood returns to the heart from the lower extremities through what ways - calf muscle pump, expiration, venous valves in a standing patient, where is the hydrostatic pressure the highest - in the feet a stenosis of 75% in area is equal to what percent of stenosis in diameter - 50% in the exercising patient, what is the response to peripheral resistance with arteriolar dilatation - the peripheral resistance decreases what will be seen with a stationary reflector - the incident frequency is equal to the reflected frequency what happens as the frequency of the transducer increases - the amount of scatter is increased what occurs as the doppler angle is increased - it decreases the frequency shift what component of the ultrasound machine is used to detect positive versus negative frequency shifts - phase quadrature what is true for CW doppler devices - it must have at least two piezoelectric elements what will result in aliasing - undersampling of the blood flow which mathematical processing technique is used to analyze the data and produce a spectral wave form - fast fourier transform what represents the resistive index - peak systolic velocity minus the end diastolic velocity divided by the peak systolic velocity what does the brightness of the dots that make up the spectral display represent - the number of red blood cells present what describes the principle that an object at rest will stay at rest unless acted on by an outside force - inertia in order to add more spectral doppler waveforms to the display, what setting on the machine should be adjusted - sweep speed what may result if the spectral doppler gain is too high - overmeasurement of the velocities the doppler shift is lowest at what angle to flow - 90 degrees which signal processing technique used for color doppler is not as accurate as, but is faster than the technique used for spectral doppler - autocorrelation what is the smallest number of crystals a PW doppler device may have - one which type of doppler does not rely on the frequency shift but instead relies on the strength of the shift - power doppler what is it called when the 2d image, color doppler image, and spectral doppler are displayed simultaneously - triplex mode what is the duty factor of cw doppler - 1 or 100% what is true about CW doppler - there is a large sample volume that obtains signals from all vessels within when compared to 2d grayscale imaging, what is true of color doppler - there is worse temporal resolution what frequency shift would exhibit aliasing if the PRF is 5,000 Hz - 3 kHz what is true about the frequency shift - it is in the audible range of sound what can be said about the ensemble length of color doppler - it is about 10 to 20 pulses per scan line what happens if blood flow is sampled in the center of laminar flow - there will be a higher velocity than if sampled toward the edges what is a property of power doppler - signal is obtained by detecting amplitude of shift assuming flow is constant, what happens in a region of blood vessel narrowing - there is an increase in the velocity along with a corresponding decrease in pressure what is true about the spectral doppler envelope - it is thickened in the center of a laminar flow vessel what is the term for the pressure difference between the inside of a vein and the tissue outside - transmural pressure a proximal stenosis will look like what on the spectral waveform - delay in the systolic upstroke the low velocity component is missing on a spectral waveform. what should be adjusted to fix this - wall filter in the exercising patient, the distal arterioles are dilated. what type of flow pattern would most likely be demonstrated on spectral doppler within the proximal vessels - monophasic flow comprehensive preventative maintenance must be performed at least - semianually which test object uses a moving belt, vibrating string or a fluid pump - doppler phantom what tests the ability of reflectors to be accurately imaged within the first centimeter of the sound beam - dead zone the test used to evaluate the depth of reflectors from a transducer is called - vertical depth calibration the only certifying agency that offers credentialing exams for cardiac and vascular testing is - CCI what is a voluntary process that acknowledges an organization's competency and credibility according to standards and essentials set forth by a reliable source - accredidation what is the system's ability to detect weak echoes - sensitivity what type of errors will cause artificial echoes to appear within a cystic structure - slick thickness what indicates the maximum depth of visualization - vertical distance what is a methodical way of evaluating equipment's performance on a routine basis to ensure proper and accurate equipment function - preventative maintenance