SPI PRACTICE QUESTIONS & Answers. 100% Accurate, latest version. Rated A

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SPI PRACTICE QUESTIONS & Answers. 100% Accurate, latest version. Rated A Sound waves are: - ✔✔longitudinal, mechanical The speed of sound in soft tissue is closest to: - ✔✔1,500 m/s The f ... requency closest to the lower limit of ultrasound is: - ✔✔15,000 Hz Which is not an acoustic variable? - ✔✔intensity The effects of soft tissue on ultrasound are called: - ✔✔acoustic propagation properties All of the following are true EXCEPT: - ✔✔two waves with identical frequencies must interfere constructively Put in decreasing order: deci, deca, micro, centi - ✔✔deca, deci, centi micro ______________ is the time to complete one cycle - ✔✔period Which of the following sound waves is ultrasonic and least useful? - ✔✔30 KHz What is the frequency of a wave with a 1 msec period? - ✔✔1 KHz ______________ is the distance covered by one cycle - ✔✔wavelength Which of the following is determined by the source and the medium? - ✔✔range resolution Propagation speed = ______________ x wavelength - ✔✔frequency As a result of ______________, the propagation speed increases - ✔✔decreasing compressibility and density Put in decreasing order of propagation speed: gas, liquid, solid - ✔✔solid, liquid, gas If the frequency of US is increased from 0.77 MHz to 1.54 MHz, what happens to the wavelength? - ✔✔halved A sound wave's frequency is 10 MHz. The wave is traveling in soft tissue. What is its wavelength? - ✔✔.15 mm If the frequency of an US wave is doubled, what happens to the period? - ✔✔halved If the frequency of US is increased from 0.77MHz to 1.54MHz, what happens to the propagation speed? - ✔✔remains the same The units of PRF are: - ✔✔per minute The time from the beginning of a pulse until its end is ______________? - ✔✔pulsed duration What happens to the speed of sound in a medium when the bulk modulus of the medium increases? - ✔✔faster ___________ resolution is determined by SPL - ✔✔radial or axial If a wave's amplitude is doubled, what happens to the power? - ✔✔quadrupled 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? - ✔✔halved Which of these intensities is the smallest? SATP, SPTP, SATA - ✔✔SATA The duty factor for CW ultrasound is: - ✔✔1.0 What is the minimum value of the duty factor? - ✔✔0% What are the units of intensity? - ✔✔watts/cm2 What happens to the speed of sound in a medium when the bulk modulus of the medium decreases? - ✔✔slower The units of attenuation are ______; this is a ______________ scale - ✔✔dB, logarithmic Sound intensity is decreased by 75%. How many decibels of attenuation is that? - ✔✔6 dB The fundamental frequency of a transducer is 2.5 MHz. What is the second harmonic frequency? - ✔✔5 MHz 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 microseconds. What is the reflector depth? - ✔✔10 cm If a 5 MHz sound wave is traveling in the tissues listed below, which will have the longest wavelength? - ✔✔bone If a 5 MHz sound wave is traveling in the tissues listed below, which will have the shortest wavelength? - ✔✔air What is the approximate attenuation coefficient of 1 MHz US in soft tissue? - ✔✔.5 dB/cm Rayl is the unit of: - ✔✔impedance Impedance is the _________ of _________ and _________ - ✔✔product, propagation speed, density What are attenuation's three components? - ✔✔scattering, reflection, absorption For soft tissue, the approximate attenuation coefficient in dB/cm is equal to one-half _________ in _________ - ✔✔frequency, MHz As the impedance of two media become vastly different , the: - ✔✔reflection increases The angle between two media is 90 degrees. What is this called? - ✔✔orthogonal incidence The angle between two media is 56 degrees. This is called: - ✔✔oblique incidence Refraction only occurs if there are: - ✔✔oblique incidence and different propagation speeds With normal incidence, what factors affect refraction? - ✔✔none of the above T/F: With right angle incidence, reflections are always generated at a boundary if the propagation speeds of the media are different - ✔✔false _________ is a redirection of US in many directions as a result of a *rough* boundary between two media - ✔✔scattering Which of the following tissues will most likely create Rayleigh scattering? - ✔✔red blood cells T/F: With normal incidence, the angle is 180 degrees. - ✔✔false Under which of the following conditions is axial resolution improved? - ✔✔decreased SPL Snell's law describes the physics of: - ✔✔refraction The most likely amount of reflection at a boundary between soft tissues is: - ✔✔1% The most typical amount of transmission at a boundary in biologic media is: - ✔✔99% Sound is traveling from medium 1 to medium 2. Propagation speeds of M1 is 1,600 m/s and M2 is 1,500 m/s. There is oblique incidence - ✔✔angle of incidence = angle of reflection T/F: Doppler shifts ALWAYS occur is the sound source and receiver are in motion - ✔✔false Which of the following is associated with power Doppler? - ✔✔poor temporal resolution and flash artifact The Doppler shift is a measure of: - ✔✔difference between incident & reflected frequencies T/F: The sonographer CANNOT change, directly or indirectly, the duty factor of an US machine - ✔✔false Depth calibration of a machine measures 100 mm spaced wires to be 90 mm apart. Scanning reflectors 50 mm apart, what will the machine calculate the distance to be? - ✔✔45 mm T/F: There have NOT been biological effects from US found in the labratory - ✔✔false How many cm are 60 mm? - ✔✔6 T/F: Lateral resolution is also called azimuthal - ✔✔true T/F: Lateral resolution is also called longitudinal - ✔✔false What increases patient exposure? - ✔✔exam time T/F: Shadowing may result from high amounts of reflection of US energy - ✔✔true Where are harmonics created? - ✔✔in the tissues How is range ambiguity artifact eliminated? - ✔✔lower the PRF For Doppler, which incident angle results in NO shift? - ✔✔90 degrees Which transducer would be best to image superficial structures? - ✔✔small diameter, high frequency A transducer with more than one active element is called: - ✔✔array How many bits are needed to represent 16 shades of grey - ✔✔4 What information does Doppler shift provide? - ✔✔velocity T/F: A sound wave is made of compressions and rarefactions - ✔✔true A hydrophone is used to measure: - ✔✔intensity (or frequency) Images on videotapes are stored using: - ✔✔magnetism Circumferences may be measured in the unit of: - ✔✔cm Decimal uses a base of 10, binary uses a base of: - ✔✔2 If the frame rate increases and the lines per frame is un [Show More]

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