ARDMS SPI EXAM QUESTIONS AND ANSWERS VERIFIED 100% CORRECT

ARDMS SPI EXAM QUESTIONS AND ANSWERS VERIFIED 100% CORRECT What type of wave is sound? - ANSWER- mechanical and longitudinal The frequency ranges for ultrasound are: - ANSWER- 20 kHz The speed of sound in soft tissue is: - ANSWER- 1540 m/s which of the following transducers fires the elements in groups? A. Linear sequenced array B. Phased array C. Continuous-wave transducer D. Single-element transducer - ANSWER- A Enhancement is caused by** - ANSWER- weakly attenuating structures wavelength in material having a propagation speed of 1.5mm/µs w/transducer frequency of 5.0 MHz is: ** - ANSWER- .3mm 1.5mm/µs / 5MHz =.3mm An ultrasound transducer converts ** - ANSWER- electrical energy into mechanical energy Media lowest attenuation to highest: ** - ANSWER- Fat, Muscle, Bone, Air Media propagation speed from lowest to highest: ** - ANSWER- Air, Fat, Muscle, Bone If the frequency doubles, what happens to the wavelength? ** - ANSWER- Decreases by 1/2 (inversely related) What happens to intensity if amplitude of signal is 1/2? ** - ANSWER- Quartered % of time that sound is on - ANSWER- Duty Factor A 3 dB gain would indicate an increase in intensity of ______ times. ** - ANSWER- 2 times Ignoring the effects of attenuation, the intensity of the ultrasound beam is usually greater at the focal zone because of. ** - ANSWER- smaller beam diameter Attenuation denotes. ** - ANSWER- Progressive weakening of the sound beam as it travels which of the following has the lowest intensity ** A. SPTP B. SATP C. SPTA D. SATA - ANSWER- D =LOWEST A=HIGHEST** definition of the beam uniformity ratio?** - ANSWER- Spatial peak intensity divided by spatial average (SP/SA) Continuous-wave doppler has a duty factor of: - ANSWER- 100% (always on) spatial pulse length is a product of the _____ & the number of _______ in a pulse? - ANSWER- wavelength & Cycles If the gain of an amplifier is 18 dB, what will the new gain setting be if the gain setting is reduced by one-half? ** - ANSWER- 15dB (1/2=-3dB therefore, 18dB3dB=15dB) True or False: SPTP is always equal to or greater than SPTA ** - ANSWER- True If the amplitude of a wave is increased threefold, the power will: ** - ANSWER- Increase NINEfold (amp squared) ultrasound attenuates an average of ____ dB/cm of travel for each megahertz of frequency. ** - ANSWER- .7 If the intensity transmission coefficient is 0.74, the intensity reflection coefficient will be: ** - ANSWER- .26 (IRC & ITC must =100) Acoustic impedance is a product of: ** - ANSWER- speed of sound in tissue & density of the tissue reflector whose size is smaller than the wavelength ** - ANSWER- Rayleigh Scattering Total attenuation of a 3.5MHz pulse after passing thru 2cm of soft tissue?** - ANSWER- 3.5dB The thinner the piezoelectric element: ** - ANSWER- the higher the frequency The unit for impedance is ________. - ANSWER- Rayl A sound beam encounters an interface at a 90* angle. If the speed of sound in the first tissue is 1540m/s & speed of sound in second tissue is 1450 m/s, what is approximate angle of beam transmission? - ANSWER- 90* (no refraction) A decibel describes the: - ANSWER- RATIO of 2 sound intensities Attenuation coefficient of sound in soft tissue can be defined by what equation? ** - ANSWER- frequency/2 (1/2 of freq) The intensity transmission coefficient is equal to: - ANSWER- 1-intensity reflection coefficient The range equation explains: ** - ANSWER- distance to reflector The typical value for attenuation coefficient for 6 MHz ultrasound in soft tissue is - ANSWER- 3dB/cm (1/2 the freq) What must be known to calculate the distance to a reflector? - ANSWER- Travel time, propagation speed Specular reflection occurs when - ANSWER- interface(border) is larger than the wavelength The layers material within the transducer which has an intermediate impedance between the transducer element & human tissue is known as: ** - ANSWER- Matching Layer What relates bandwidth to operating frequency? ** - ANSWER- Quality Factor (OF/bandwidth) the piezoelectric effect can be best described as: - ANSWER- piezoelectric crystals subject to pressure resulting in an electrical charge appering on their surface.