SPI Practice Test.docx

Which of the following do the source and the medium determine? a. duty factor b. frequency c. propagation speed d. axial resolution - correct answer d. Axial resolution is affected by all of the following EXCEPT a. frequency b. damping c. spatial pulse length d. focusing - correct answer d. Damping in a transducer a. reduces the number of cycles in a pulse and increases the quality factor b. increases the number of cycles in a pulse and increases penetration c. causes poor axial and lateral resolution d. reduces the duty factor and increases the range of transmitted frequencies - correct answer d. Far zone beam divergence can be reduced on a single-element transducer by using a. a transducer with a smaller element diameter b. a higher frequency transducer c. a lower frequency transducer or a smaller element diameter d. adjustable focusing - correct answer b. The area between the face of an unfocused single-element transducer and the point where the beam starts to diverge is the a. Fraunhofer zone b. refraction zone c. focal zone d. near zone - correct answer d. Assuming a fixed frequency, what happens if the diameter of an unfocused transducer is increased? a. the far zone divergence increases b. the penetration decreases c. the length of the near zone increases d. the length of the near zone decreases - correct answer c. Which of the following does NOT affect lateral resolution? a. focusing b. element diameter c. frequency d. bandwidth - correct answer d. Higher frequency transducers provide a. improved lateral resolution b. smaller Doppler shifts c. improved axial resolution and reduced attenuation d. increased penetration - correct answer a. Ultrasound waves that are traveling through a medium consist of a. electromagnetic and radio frequencies b. compressions and refractions c. electromagnetic and ionizing frequencies d. compressions and rarefactions - correct answer d. What is the difference between audible sound and ultrasound? a. audible sound waves can travel through a vacuum b. audible sound has a higher frequency c. ultrasound has a higher frequency d. ultrasound waves are ionizing - correct answer c. A decrease in the thickness of a piezoelectric element will result in a. a greater pulse duration b. an increase in the propagation speed c. a decrease in the quality factor if the bandwidth decreases d. an increase in the frequency of the transducer - correct answer d. The resonant frequency of a pulsed-wave ultrasound transducer is dependent on a. damping b. the backing material c. the thickness of the piezoelectric element and the speed of sound through the piezoelectric element d. the amplitude of the voltage applied to the piezoelectric element - correct answer c. The image is brighter at the level of the focal zone. Which of the following controls is best to correct this? a. overall gain b. TGC c. acoustic power d. PRF - correct answer b. If the frequency is doubled, a. the duty factor will increase b. the period will double c. the wavelength will double d. the wavelength will be one-half - correct answer d. The typical range of pulse repetition frequencies in a pulse-echo ultrasound system is a. 2,000 Hz to 20,000 Hz b. 20 MHz to 200 MHz