ARDMS SPI Exam Review with Complete Solutions

Example of nonspecular reflector - ANSWER-red blood cells What happens to spatial pulse length when frequency increases? - ANSWER-decreases Axial resolution is dependent on? - ANSWER-wavelength Lateral resolution is dependent on? - ANSWER-beam diameter Where does the beam of an unfocused transducer diverge? - ANSWER-Fraunhofer zone Reverberation artifacts are a result of - ANSWER-two or more strong reflecting surfaces True/False: Grating lobes are essential for the proper operation of a linear phased array. - ANSWER-False True/False: Electronically steered scanners always produce higher resolution images than do mechanically steered scanners. - ANSWER-False True/False: An annular array scanner uses mechanical beam steering. - ANSWER-True True/False: A linear sequenced array cannot be dynamically focused. - ANSWER-False registration or B-mode alignment - ANSWER-Which AIUM test object function utilizes all the groups of wires in the AIUM 100 mm test object? axial resolution - ANSWER-Which AIUM test object function utilizes the A group of wires in the AIUM 100 mm test object? lateral resolution - ANSWER-Which AIUM test object function utilizes the B group of wires in the AIUM 100 mm test object? dead zone - ANSWER-Which AIUM test object function utilizes the D group of wires in the AIUM 100 mm test object? depth calibration - ANSWER-Which AIUM test object function utilizes the C or E groups of wires in the AIUM 100 mm test object? What happens to axial resolution when spatial pulse length is decreased? - ANSWER-improves How much will a 3.5 MHz pulse be attenuated after passing through 2 cm of soft tissue? - ANSWER-3.5 dB Propagation speed errors result in - ANSWER-improper axial position Enhancement is caused by - ANSWER-weakly attenuating structures The Doppler shift frequency is - ANSWER-directly proportional to the velocity of the reflector The number of frames per second necessary for a real-time image to be flicker free is - ANSWER-more than 15 True/False: The SPTA intensity will always be larger than the SATA intensity. - ANSWER-True The intensity of the ultrasound beam is usually greater at the focal zone because of - ANSWER-the smaller beam diameter If the amplitude is doubled, the intensity is - ANSWER-quadrupled The attenuation for soft tissue is - ANSWER-increased with tissue thickness The acoustic impedance of the matching layer - ANSWER-can be chosen to improve transmission into the body True/False: In a pulse-echo system, the quality factor should be made as large as possible. - ANSWER-False True/False: The beam diameter is constant in the near zone. - ANSWER-False The operating frequency is dependent on - ANSWER-thickness of the crystal The period of an ultrasound wave is - ANSWER-the time of one wavelength The dynamic range of a system is - ANSWER-the ratio of smallest to largest power level that the system can handle True/False: The intensity of an ultrasonic beam can be measured with radiation force balance. - ANSWER-True Increasing the pulse repetition period - ANSWER-increases the maximum depth that can be imaged Ultrasound bioeffects - ANSWER-are not confirmed below 100 mW/cm² SPTA True/False: No refraction can occur at an interface if the media impedances are equal. - ANSWER-False True/False: Smaller transducers always produce smaller beam diameters. - ANSWER-False True/False: The ultrasound beam profile can be measured with a hydrophone. - ANSWER-True True/False: The pulsed-Doppler system yields better depth resolution than the continuous wave (CW) system. - ANSWER-True True/False: The gray-scale display was made possible when digital scan converters replaced analog scan converters. - ANSWER-False True/False: Videotape recorders operating at 30 frames per second cannot be used with mechanical real-time units because the fram rate is too slow. - ANSWER-False True/False: Linear phased array scanners need no form of mechanical focusing because focusing is performed electronically. - ANSWER-False True/False: The fram rate of real-time scanners depends on the number of lines used to form the image. - ANSWER-True True/False: It is not possible to steer an annular phased array electronically. - ANSWER-True True/False: The near zone length should be kept as short as possible. - ANSWER-False What percentage of intensity of an ultrasound pulse incident on an interface of 0.25 and 0.75 rayls is reflected? - ANSWER-25% Axial resolution can be improved by using - 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 - ANSWER-longitudinal wave The wavelength in a material having a wave velocity of 1500 m/s emplying a transducer frequency of 5 MHz is - ANSWER-0.3 mm The factor that determines the amount of reflection at the interface of two dissimilar materials is - ANSWER-difference in acoustic impedances