__________ is the reciprocal of period. A. inverse period B. PRP C. frequency D. propagation speed - C. Frequency A bouquet has 30 flowers. The size of the bouquet is decreased by a factor of 3. How many flowers remain? A. 27 B. 0 C. 10 D. 15 - C. 10 A byte is composed of __ bits. A word is composed of ___ bytes. A. 2, 2 B. 8, 2 C. 16, 16 D. 8, 16 - B. 8, 2 (a string of eight bits of computer memory is a byte. Two bites of computer memory make a word. Since a byte is 8 bits, a word is 16 bits) A comprehensive and scholarly review of bioeffects is performed by the American institute of ultrasound in medicine for all of the following reasons except A. ultrasound is a versatile technique B. ultrasound has proven widespread clinical utility C. ultrasound is considered highly toxic D. applications of ultrasound are growing considerably - C. Ultrasound is considered highly toxic A duplex ultrasound system displays ___ information A. M-mode, two-dimensional image, and A mode B. A-mode and B-mode C. two-dimensional image and Doppler D. two-dimensional image and M-mode - C. two-dimensional image and Doppler (a duplex scanner displays both Doppler and two-dimensional image data). A force is applied to a surface. If the force is tripled and the surface area over which the force is applied is also tripled, what is the new pressure? A. three times larger than the original B. one third of the original C. six times more than the original D. unchanged - D. Unchanged A longitudinal wave propagates from east to west at a speed of 2 miles per hour. What is the direction of motion of the particles within the wave? A. from east to west only B. alternately from east to west and then from west to east C. from north to south only D. alternately from south to north and then from north to south - B. Alternately from east to west and then from west to east A maximum Doppler shift is obtained when the angle between the direction of blood flow and the direction of the sound beam is ___ A. 10 degrees B. 90 degrees C. 180 degrees D. 270 degrees - C. 180 degrees. (max Doppler shifts ccur when red blood cells travel directly toward or directly away from a transducer. an angle of 180 degrees between the sound source and the direction of motion exists when the cells travel away from the transducer). A pair of waves are in phase. What occurs when these waves interfere? A. reflection B. constructive interference C. refraction D. destructive interference - B. Constructive interference A particle within a transverse wave is traveling vertically. What is the direction of the wave's propagation? A. horizontal B. vertical C. diagonal; both horizontal and vertical D. cannot be determined - A. Horizontal A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: if the diameter of a sound beam is 8 mm at the depth equal to twice the near zone length, then the PZT crystal has a diameter of 16 mm. - FALSE; when a CW is produced by a disc shaped crystal, the beams diameter equals the crystals diameter at a depth that is twice the near zone length. A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: if the diameter of the acoustic beam produced by a crystal is 8 mm at a depth of twice the NZL, then the PZT crystal has a diameter of 8 mm. - TRUE A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: If the narrowest diameter of a sound beam is at a depth of 8 cm, then the PZT crystals diameter is 16 cm. - FALSE; the depth of the focus is not determined solely by the diameter of the piezoelectric crystal producing it. A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: the far zone is the only region where the beam diameter exceeds the transducer diameter. - TRUE A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: the greater the diameter of a transducers piezoelectric crystal, the longer the near zone length is. - TRUE A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: the higher the frequency of the acoustic wavem the shorter the length of the near zone - FALSE> the focus gets deeper as the frequency of the wave increases. With low frequency sound ,the focus is shallower. A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: the near zone is the only region where the diameter of the sound beam is smaller than the transducers. - FALSE. The sound beam created by a disc shaped continuous wave crystal is smaller than the crystal in the near zone and the initial part of the far zone A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: the NZL is the only region where the diameter of a sound beam decreases as depth increases - TRUE A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: the thicker a CW transducers piezoelectric crystal, the longer the NZL is. - FALSE. Increasing the thickness of a piezoelectric crystal does not alter the length of the near zone of a continuous wave ultrasound beam. A sack contains 6 lbs of flour. The contents of the bag are increased by a factor of 5. How much flour is in the bag? A. 6 pounds B. 11 pounds C. 60 pounds D. 30 pounds - D. 30 pounds A signal with a 120 dB dynamic range is compressed by 40 dB. what is the dynamic range of the compressed signal? A. 40 dB B. 120 dB C. 3 dB D. 80 dB - D. 80 dB. (when a signals dynamic range is compressed, the decibels of compression are simply subtracted. in this case. 120-40=80 dB) A signal with a 120 dB dynamic range was previously compressed by 40 dB. what is the dynamic range of the original uncompressed signal? A. 160 dB B. 120 dB C. 3 dB D. 80 dB - A. 160 dB (when a signal is already compressed, the original dynamic range is obtained by adding the decibels of compression. in this case, 120 + 40 = 160 dB) A sonographer adjusts the max imaging depth of an ultrasound system. Which of the following also changes? (more than one answer may be correct) A. PRP B. wavelength C. PRF D. frequency - A and C. PRP and PRF. (the wavelength and frequency remain constant, as these terms describe the attributes of a single cycle within the pulse, and are not affected by alterations in imaging depth.) A sonographer adjusts the output power of the wave emitted by the transducer. Which of the following also changes? ( more than one answer may be correct.) A. pulse repetition period B. PRF C. propagation speed D. intensity - D. Intensity A sonographer is performing a study on a patient and desires superior depth resolution. Which of the following changes would create such a system? A. higher frequency B. shorter wavelength C. fewer cycles per pulse D. less ringing E. all of the above - E. All of the above A sonographer measures the perimeter of an anatomical structure. Which of the following choices is a reasonable value for this measurement? A. 6 cm^2 B. 5 cc C. 15 mm D. 10 dB - C. 15 mm A sonographer reduced the sector size from 90 degrees to 30 degrees. Frame rate, however, did not change. What else happened? A. imaging depth decreased B. pulse duration increased C. multi-focus was turned on D. PRF was increased - C. Multi-focus was turned on A sound beam travels 9cm in soft tissue. The attenuation coefficient is 3 dB/cm. What is the total attenuation that the sound beam experienced? A. 9dB B. 3 dB C. 27 dB D. 18 dB - C. 27 dB. (to calculate total attenuation, multiply path length by attenuation coefficient. 3 x 9 = 27 dB) A sound beam with an intensity of 45 W/cm^2 strikes a boundary and 70 % of the waves intensity is reflected. How much is transmitted? A. 45 W/cm^2 B. 25 W/cm^2 C. 30 % D. 100% - C. 30% (the law of conservation of energy states that the sum of the percentage of transmitted sound and the reflected sound equals 100%.) A sound pulse strikes a boundary between two media with normal incidence. The speed of sound in the two media are very different; however, the impedances of the media are identical. What will happen? A. a big echo will be produced B. a medium echo will result C. a small echo will result D. there will be no echo at all - D. There will be no echo at all A sound wave reaches a rough or irregular border between two media. Under these explicit circumstances, which process is most likely to occur? A. backscatter reflection B. specular reflection C. Rayleigh scattering D. refraction - A. Backscatter reflection A sound wave strikes a boundary between two media at a 60 degree angle. This is called ______ incidence. A. orthogonal B. angular C. obtuse D. oblique - D. Oblique A spectral sector shape is produced when this transducer is used. It looks like a wedge or a slice of pie, but it doesn't originate at a point. The sector has a blunted, curved shape at the top. The arc at the top of the image may be a few centimeters wide.