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ARDMS SPI EXAM LATEST 2024-2025 UPDATE
COMPREHENSIVE QUESTIONS AND CORRECT DETAILED
ANSWERS| ALREADY GRADED A+/100% PASS
What percentage of intensity of an ultrasound pulse incident on an interface of 0.25 and 0.75 rails is reflected? - Correct Answer - 25%
Axial resolution can be improved by using - Correct Answer - higher frequency transducers
When particle motion of a medium is parallel to the direction of a wave propagation, the wave being transmitted is called a - Correct Answer - longitudinal wave
The wavelength in a material having a wave velocity of 1500 m/s employing a transducer frequency of 5 MHz is - Correct Answer - 0.3 mm
The factor that determines the amount of reflection at the interface of two dissimilar materials is - Correct Answer - difference in acoustic impedances
The equation that describes the relationship among propagation, wavelength, and frequency is - Correct Answer - λ = c/ƒ
What three things can occur when an ultrasonic beam reaches the interface of two dissimilar materials? - Correct Answer - reflection, refraction, mode conversion
The acoustic impedance of a material is - Correct Answer - equal to the product of density and velocity
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The average velocity of ultrasonic waves in soft tissue is - Correct Answer - 1540 m/s
True/False: Receiver-angle values in CW Doppler analysis do not influence the final Doppler shift. - Correct Answer - False
Refraction occurs because of difference in ______ across an interface between two materials - Correct Answer - wave velocity
Reflection factor at an interface between two materials depends primarily on the change in ______ across the interface. - Correct Answer - acoustic impedance
The velocity of sound waves is primarily dependent on - Correct Answer - medium and mode of vibration
Increasing the frequency of an ultrasonic longitudinal wave will result in ______ in the velocity of that wave. - Correct Answer - no change
The change in direction of an ultrasonic beam, when it passes from one medium to another, in which elasticity and density differ from those of the first medium is called - Correct Answer - refraction
A long near zone can be obtained by - Correct Answer - using a higher frequency transducer
If a 2 MHz frequency is used in human soft tissue, the wavelength is approximately - Correct Answer - 0.75 mm
The ratio of particle pressure to particle velocity at a given point within the ultrasonic field is - Correct Answer – impedance
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pg. 3 What is the following formula used to determine?(2 × velocity of reflector × original frequency) / velocity of sound - Correct Answer - Doppler shift frequency
The principle that states that all points on a wavefront can be considered as point sources for the production of spherical secondary wavelets was postulated by - Correct Answer - Huygens
A 10 dB difference in signal intensity is equivalent to a _______ difference. - Correct Answer - tenfold
The level below which signals are not transmitted through an ultrasound receiver system is the - Correct Answer - threshold, negative, reject level
Gray-scale systems typically use _____ as a means of signal dynamic range reduction.
- Correct Answer - compression
The strength of the echo is related to the height of the deflection on the oscilloscope for the ____ display. - Correct Answer - A-mode
What are methods of restricting the dynamic range of the signal? - Correct Answer - suppression, rejection, compression
Most of the scan converters currently in use are of the _____ type? - Correct Answer - digital
The fraction of time that pulsed ultrasound is actually on is the - Correct Answer - duty factor
The ability of an imaging system to detect weak reflections is called - Correct Answer - sensitivity
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pg. 4 What image shape is produced by a linear sequenced array transducer? - Correct Answer - rectangular
The major factor in determining the acoustic power output of the transducer is the - Correct Answer - magnitude of the voltage spike
Two primary mechanisms that produce tissue biological effects are - Correct Answer - thermal and cavitation
The _____ relates bandwidth to operating frequency. - Correct Answer - quality factor, Q Factor
The extraneous beams of ultrasound generated from the edges of individual transducer elements and not in the direction of the main ultrasonic beam are called - Correct Answer - side lobes
The product of the period and the number of cycles in the pulse is the - Correct Answer
- pulse duration
The substance typically used as a matrix on the imaging surface of an analog scan converter tube is - Correct Answer - silicon oxide
Specular reflection occurs when - Correct Answer - the reflector surface is small and smooth as compared with wavelength
The refractive index of water is slightly altered when a sound beam passes through it, thus causing compression and rarefaction of the water molecules. The phenomenon is the basis for the _____ technique of beam measurement. - Correct Answer - Schlieren
Artifacts appearing as parallel, equally spaced lines are characteristic of - Correct Answer - reverberation
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