DMS 200 FINAL EXAM QUESTIONS WITH CORRECT ANSWERS LATEST UPDATE 2026

DMS 200 FINAL EXAM QUESTIONS WITH CORRECT ANSWERS LATEST UPDATE 2026 Under which conditions is lateral resolution improved? - Answers Decreased beam diameter, decreased pulse duration, decreased spatial pulse length What is the importance of the Curie temperature? - Answers The temperature at which ferroelectric material is polarized How is internal focusing accomplished? - Answers Using a curved PZT crystal, lens placed in front of PZT crystal, or phased array Which ultrasound system will have the farthest focus? - Answers The higher frequency system What happens to the power if the intensity of a sound beam remains unchanged while the beam area is doubled? - Answers Doubled What results from a malfunction of an element within a convex sequential array transducer? - Answers A band of dropout from top to bottom Which configuration results in the least amount of beam divergence in the far zone? - Answers High frequency, large diameter What happens to the pulse repetition frequency when imaging at a shallower depth? - Answers Higher What are the characteristics of imaging transducers? - Answers Low sensitivity, wide bandwidth, low Q factor What is period in ultrasound? - Answers Time to complete one cycle How thick is the active element in a transducer? - Answers One-half wavelength What two characteristics determine the focal depth of a fixed focus transducer? - Answers Transducer diameter and frequency of sound In B-mode, which axis is related to the strength of the reflection? - Answers Z-axis What best describes the beam profile that is steered and unfocused? - Answers Steered, unfocused If time of flight is 26 µs, what are the reflector depth and distance traveled? - Answers 2 cm depth, 4 cm distance What is the distance that a pulse occupies in space? - Answers Spatial Pulse Length What are the effects of soft tissue on ultrasound called? - Answers Acoustic propagation properties Which transducer is best described as mechanically steered and multi-focus? - Answers Annular phased array What is the purpose of the acoustic insulator? - Answers Isolates the internal components of the transducer from the case What is the best estimate of the diameter of the sound beam as it exits the transducer? - Answers Width of the PZT What is necessary to calculate distance to a reflector? - Answers Propagation speed and round-trip time What is the duty factor for continuous wave ultrasound? - Answers 1.0 What is the speed of sound in the medium if a sound beam travels a total of 10 cm in 2 seconds? - Answers 5 cm/s What is the speed of sound in soft tissue? - Answers 5 cm/sec What happens when the impedances of two media become vastly different with normal incidence? - Answers Reflection increases Dynamic range is a _____________ of two numbers and is measured in ____________. - Answers Ratio: dB If the frequency is doubled while traveling through the same medium, what happens to the propagation speed? - Answers Unchanged Transverse resolution describes the accuracy related to visualizing two structures that are ____________ to a sound beam. - Answers Perpendicular The lower the numerical value of the longitudinal resolution, the worse the picture. True or False? - Answers False What is the effect of an active element malfunction in an annular phased array? - Answers Horizontal dropout How is a short pulse created? - Answers High frequency, less ringing What does the red line in the image below represent? - Answers PRP Which intensity is measured at the location where intensity is maximum, averaged over the transmit time? - Answers SPPA Which intensity is most relevant with respect to tissue heating? - Answers SPTA What is the basis for measuring distances in diagnostic imaging? - Answers All of the above Low frequency transducers have: - Answers Longer wavelengths and greater penetration What is the go-return time (time-of-flight) for a depth of 10 cm in soft tissue? - Answers 130 microseconds What describes the property of certain materials to create a voltage when they are mechanically deformed? - Answers Piezoelectric effect If it takes 52 microseconds for a pulse to return as an echo, how deep is the reflector? - Answers 4 cm With constructive interference, the resulting wave is: - Answers Larger than either of its components Which of the following is NOT associated with superior axial resolution? - Answers Longer wavelength The rayl is the unit of: - Answers Impedance Pulse duration is equal to _____________________________. - Answers Number of cycles x period What is reflection in multiple directions from a reflector that is small relative to the wavelength? - Answers Rayleigh scattering What two properties establish the propagation speed in a given medium? - Answers Density and stiffness What best describes the active element(s) in an annular phased array transducer? - Answers Circular (target shaped) Which system has the shallower focus: one with a smaller diameter crystal or a larger diameter crystal? - Answers System with the smaller diameter crystal What happens to ultrasound attenuation as path length increases? - Answers Increases What does the X-axis of an A-mode display represent? - Answers Reflector depth What is the bandwidth of a pulsed-wave transducer with a resonant frequency of 7 MHz, lowest frequency of 4 MHz, and highest frequency of 10 MHz? - Answers 6 MHz What is used to focus the sound beam with external focusing? - Answers Lens How many centimeters are in 60 millimeters? - Answers 6 Which transducer has the worst axial resolution? - Answers 4 cycles/pulse, 2 MHz What is a vector array a combination of? - Answers Linear phased and linear sequential arrays What is achieved by introducing varying electrical delays in the signals returning from the transducer? - Answers Dynamic receive focusing How is total attenuation of a sound wave determined? - Answers Multiplying attenuation coefficient and path length What is azimuthal resolution also known as? - Answers Lateral resolution What determines the frequency of a continuous wave transducer? - Answers Electrical frequency What happens to the attenuation coefficient value with increasing path length? - Answers Remains the same