SPI PRACTICE QUESTIONS WITH COMPLETE SOLUTIONS

SPI PRACTICE QUESTIONS WITH COMPLETE SOLUTIONS Sound waves are: longitudinal, mechanical The speed of sound in soft tissue is closest to: 1,500 m/s The frequency 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