Ultrasound Physics Ch. 13,16,18,19, ?

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

A system has 3 transducers with frequencies of 7.5 MHz, 5 MHz and 3.25 MHz. Aliasing appears while using the 5.0 exam. What should the sonographer do? A. use the 3.25 MHz B. use the 7.5 MHz C. nothing

A

All of the following are related to a dedicated continuous wave Doppler transducers except: A. wide bandwidth b. high quality factor c. range amiguity

A

The arterial blood pressure of a standing individual is 120 mmHg. What is the hydrostatic pressure at the subject's ankle? A. 100 mmHg B. 0 mmHg C. 40 mmHg

A

What happens to the diaphragm when an individual breathes out? A. it ascends into the thorax B. it descends into the abdomen

A

What happens to venous flow in the legs when an individual exhales? A. increases b. decreases c. remains the same

A

What is coaptation? A. vessel collapse b. blood clotting c. capillary filtration d. bernouli's flow

A

What is the primary reason why blood moves from one location to another? a. energy gradient b. anemia c. pressure gradient d. friction

A

Wheat happens to venous return to th eheart when an individual inhales? A. increases b. decreases c. remains the same

A

Which of the following determines the grayscale in a Doppler spectrum? A. number of reflectors b. velocity c. frequency shift

A

Which of these components typically has the greatest dynamic range? A. display B. pulser c. amplifier d. demodulator

A

Which one of the following does not belong in the group below? A. receiver gain B. energy output B. pulser power c. acoustice power d. transmitter power e. output gain

A

Which ultrasound imaging modality has the best temporal resolution? A. m-mode B. duplex imaging C. color flow imaging

A

Why is it necessary for the receiver to perform compression on the electrical signals that it processes? A. dynamic range of the systems electronics is less than the dynamic range of the received sound reflection B. the displays dynamic range of the receiver is less than the dynamic range of the image processor

A

The process of demodulation incorporates which of the following tasks? A. smoothing B. amplification C. rectification D. decompression

A, C

Which of these functions are performed by the reciever of an US system? A. amplification B. threshold c. compensation d. demodulation

A,B,C,D

2 ultrasound transducers are used to perform doppler exams on the same patient. The exams on the same patient. The exams are identical except that the transducer frequencies are 5 and 2.5 MHz. Which exam will measure highest doppler shift? A. the 2.5 MHz B. the 5 Mhz C. neither

B

All of the following reduce temporal resolution by increasing th enumber of pulses per image except: A. increasing the number of foci B. increasing depth of view C. increasing line density

B

In standard Doppler, what is true about the reflected frequency produced by blood cells traveling in a direction away from the transducer? A. it is the audible range B. it is ultrasonic C. it exceeds the transmitted frequency

B

The 2 most common color maps used in color flow imaging are: A. variance and direct B. variance and velocity C. turbulent and variance D. power and velocity

B

The analysis of Doppler spectra using ____ is most accurate. A. zero-crossing detectors B. fast fourier transforms c. time interval histograms

B

The arterial blood pressure of a supine individual is 120 mmHg. What is the hydrostatic pressure at the subjects ankle? A. 100 mmHg b. 0 mmHg c. 40 mmHg d. 120 mmHg

B

The output of an US pulser determines the ____ of the acoustic pulse. A. imaging depth B. intensity C. duration D. PRP

B

The process of eliminating low amplitude signals from further processing is called all of the following except ____. A. reject B. subordination C. threshold D. suppression

B

What does the far gain of a depth gain compensation curve represent? A. the median amplification related to compensation b. the maximum amplification related compensation c. the minimum amplifcation related compensation

B

What happens to the diaphragm when an individul breathes in? A. It ascends into the thorax B. It descends into the abdomen

B

What happens to venous flow in the legs when an individual inhales? A. increases b. decreases c. remains the same

B

What happens to venous return to the heart when an individual exhales? A. increases b. decreases c. remains the same

B

What is the primary disadvantage of multiple focal zones along each scan line of a 2-d image? A. improved temporal resolution B. decreased temporal resolution C. improved lateral resolution D. improved longitudinal resolution

B

What is the process of adjusting for path length related attenuation called? A. compression b. compensation c. GTC d. reconfirmation

B

When red blood cells move away from a transducer, the frequency of the wave reflected from the red cells is ____ the frequency emitted by the transducer. A. greater than b. less than c. equal to

B

Which choice will result in increased frame rate and temporal resolution? A. decreased prop speed B. decreased sector size C. decreased lateral resolution D. decreased PRF

B

Which of the following causes the greatest amount of inertial energy loss? A. pulsatile flow b. flow through a stenosis c. phasic flow

B

Which transducer system is most likely to have the longest delay in its TGC curve? A. 5 MHz linear array B. 2.5 MHz annular array C. 7.5 MHz mechanical

B

The arterial blood pressure of a supine individual is 120 mmHg. What is the hydrostatic pressure at the subject's hips? A. 100 mmHg B. 0 mmHg C. 40 mm Hg

B.

2 US transducers are used to perform Doppler exams on the same patient. The exams are identical except that the transducer frequencies are 5 and 2.5 MHz. Which exam will measure the highest velocities? A. the 2.5 MHz exam B. the 5 MHz exam C. neither

C

2 otherwise identical Doppler studies are performed, except that the angle between flow and the sound beam is 0 degrees in the first study and 60 degrees in the second. The velocity measured in the first study is 2 m/s. What velocity will be measured in the second study? A. 2 m/s B. 4m/s C. 1 m/s D. cannot be determined

C

A duplex ultrasound system displays ____ information. A. m-mode, 2-d image, and a mode B. a mode, b- mode c. 2d image and doppler

C

A max 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

A sonogrpaher reduced the sector size from 90 degrees to 30 degrees. The frame rate, howver, did not change. What else happened? a. imaging depth decreased b. pulse duration increased c. multi-focus was turned on

C

All of the following are associated with a CW Doppler transducer except: A. narrow bandwitdth B. increased sensitivity C. backing material

C

All of the following are consistent with an image containing only black and white and no other shades of gray except: A. bistable b. high contrast c. wide dynamic range

C

All of the following decrease the flow energy of a fluid except: A. frictional loss b. viscous loss c. velocity loss

C

An US system with a 4.0MHz transducer is used to image structures as deep as 15 cm. Twenty images are produced each second, each requiring 100 acoustic pulses. what is the PRF of the system? A. 1500 Hz B. 300 Hz C. 2,000 Hz

C

An ultrasound system can accurately process voltage in a range from 4 volts to 400 volts. What is the systems dynamic range? A. 396 voltage B. 20 dB C. 40 dB D. 60 dB

C

At which imaging depth is the slope of the TGC curve most effective? a. the region very close to the transducer b. the far zone c. the focal zone

C

Doppler does not always provide a valid estimate of the speed of blood cells because the shift is related to the ____ of the beam and the direction of blood flow. A. sine b. tangent c. cosine d. cotangent

C

During a pulsed Doppler exam, aliasing is observed. All of the following may eliminate aliasing except: A. selection of another imaging view with a shallower sample volume B. selection of another transducer with low frequency C. selection of another imaging view that provides a greater PRP

C

If red blood cells are traveling toward a transducer, the frequency emitted by the transducer is ___ the frequency reflected from the red blood cells. A. greater than B. equal to C. less than

C

Of the following, which imaging modality has the poorest temoporal resolution? A. 2-d, real-time B. A-mode C. color flow imaging

C

Spectral analysis of color flow Doppler is most commonly performed by which of the following techniques? A. zero crossing detectors b. fast fourier transforms c. autocorrection

C

The Doppler effect is observed as a change in ____ and has units of ____. A. amplitude, watts B. power, watts c. frequency, per second

C

The arterial blood pressure a standing patient is 120 mmHg at the level of the heart. What is the measured blood pressure at the subjects ankle? a. 100 mmHg b. 0 mmHg c. 220 mmHg

C

The highest doppler frequency without the appearance of aliasing is called ____ and is equal to ____. A. aliasing limit, half of the emitted frequency B.PRF, the PRF C. nyquist limit, half of the emitted PRF d. nyquist limit, half of the frequency

C

The relationship between the largest and the smallest signal amplitudes processed by a component of an US system is called the ___ and has units of ____. A. decibels, watts b. intensity, W/cm squared C. dynamic range, dB D. proportionality, dB

C

What information does the Doppler shift furnish concerning the blood cells that produce it? A. frequency B. speed c. velocity d. density

C

What is a typical pulser output voltage that excites a piezoelectric crystal? A. 0.1 Volts B. 500 millivolts C. 110 volts D. 10 microvolts

C

What is the meaning of the term "analysis" in the context of spectral analysis of Doppler signals? A. building a sophisticated signal from components b. building a simplified signal from components c. identifying the building blocks or components for a complex signal

C

What is the primary advantage of multiple focal zones along each scan line of a 2-d image? A. improved temporal resolution B. decreased temporal resoultion C. improved lateral resolution

C

What is the range of Doppler shifts commonly measured in clinical exams? A. -10 kHz to 1 MHz B. -0.5 MHz to 0.5 MHz C. -0.01 MHz to 0.01 MHz

C

What is true of the Doppler shift when the sound beam is normally incident to the velocity of the red blood cells? a. it is a maximum b. is is half of maximum c. it is absent d. it is a minimum

C

When using a 4 MHz transducer, a Doppler shift of 3,000 Hz is recorded. What will the Doppler shift be when a 2 MHz transducer is used? A. 3,000 Hz B. 2 Hz C. 1,500 Hz D. 6,000 Hz

C

Which 2 controls determine a system's temporal resolution? A. frame rate and sector size B. focal zones and sector depth C. depth of view and pulses per image

C

Which choice relates to the presence of gray shades in a doppler spectrum? A. velocity B. frequency shift C. amplitude of the echo D. laminar flow

C

Which display is limited to a single pair of brightnesses or display levels? A. crt b. binary c. bistable d. grayscale

C

Which of the following actions will improve the signal to noise ratio? A. increase dynamic range B. increase receiver gain C. increase output power D. increase TGC

C

Which of the following is a typical value for the amplification of a signal by the receiver? a. 50 to 10 watts b. -50 to -100 dB C. 60 to 100 dB D. 5 to 25 W/cm2

C

Which of the following sector imaging systems will have the best image detail if all other parameters are identical? A. a 90 degree sector with 100 pulses/ image B. a 60 degree sector with 60 pulses/ image C. a 70 degree sector with 84 pulses/ image

C

Which of the following terms is not associated with a wide dynamic range image? a. low contrast b. many shades gray c. bistable

C

Which of the following will improve a systems temporal resolution? A. increased sector angle B. increased line density C. increased PRF D. increased frequency

C

Which of the follwoing terms does not belong with the others? a. phasic b. spontaneous c. pulsatile d. venous

C

Which receiver function creates an image of comparable brightness from top to bottom? A. receiver gain B. output power c. swept-gain compensation

C

Which term best describes the region of minimum amplification on a standard TGC curve? A. far field b. focus only c. area close to the transducer d. focal zone

C

A signal is increased form 1 mvolt to 1 volt by the amplifier. How many decibels is this? A. 1000 dB B. 20 dB C. 40 dB D. 60 dB

D

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

All of the following are used to describe compensation except: A. swept gain b. depth gain c. time gain d. amplitude gain

D

Blood moving at a velocity of 2 m/s creates a Doppler frequency of 3,000 Hz. What will the Dopller shift be if the velocity increases to 4 m/s? A. 3,000 Hz B. 2 Hz C. 1,500 Hz D. 6,000 Hz

D

In clinical imaging, which reflectors produce most relevent Doppler shifts? A. blood vessels B. blood plasma c. platelets D. red blood cells

D

The frequency of a pulsed Doppler wave is 6 MHz and the PRF is 5 kHz. What is the max Doppler shift that can be recorded without aliasing? A. 6 MHz B. 5 kHz C. 3 MHz D. 2.5 kHz

D

What is the typical voltage of the signal that is the input ot he receiver of an US system? A. 0.1 votls B. 500 mvolts c. 250 volts d. 10 uvolts

D

Which of the following best describes the demodulation process? A. changing the grayscale of an image B. changing the frequency of a signal C. changing the form of a sound pulse D. changing an electrical singals form

D

Which of the following flow patterns is associated with cardiac contraction? A. phasic b. spontaneous c. steady d. pulsatile

D

Which of the following is not considered a component of an US system? A. master synchronizer B. pulser C. receiver D. image intensifier

D

Which of the following tasks is not performed by the receiver of an US system? A. rectification B. smoothing C. compression D. deguassing

D

With pulsed Doppler, what term is used to describe a very high positive Doppler shift that is displayed as a negative waveform? A. attenuation b. filtering c. demodulation d. aliasing

D

a component of an US system can process voltages in a range from 5 volts to 50 volts. What is the dynamic range of the component? A. 45 volts b. 10 dB C. 15 dB d. 45 dB e. 20 dB

E

T or F? A diagnostic ultrasound system can produce 20 images per second, to a maximum depth of 20 cm, and create each image with 200 acoustic pulses.

F

T or F? Absence of color on a color Doppler image always indicates a region of no blood flow.

F

T or F? An ultrasound system with a longer pulse duration will generally have better temporal resolution.

F

T or F? Color Flow Doppler relies on pulsed Doppler principles and is immune to aliasing artifact.

F

T or F? The higher the PRF of a doppler exam, the more likely aliasing is to occur.

F

T or F? The lower the frequency of the US beam, the shallower the delay of the TGC curve.

F

T or F? The pulse of a mechanical transducer is typically more complex than the pulser of a phased array transducer.

F

T or F? The sonographer can make an image of uniform brightness by adjusting both output power and receiver gain.

F

T or F? Typically, the sonographer can control the demodulation process performed by a receiver.

F

T or F? Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are turbulent.

F

T or F? With CW Doppler problems with allasting significantly limit its clinical utility.

F

T or F? on a color doppler image, red always represents flow toward the transducer, whereas blue indicates flow away from the transducer.

F

T or F? the appearance of negative velocities in a pulsed Doppler display always indicates that red blood cells are moving away from the transducer.

F

T or F? A minimum of 2 distinct piezoelectric crystals are in the transducer in CW doppler.

T

T or F? An ultrasound system with a shorter PRP will have better temporal resolution than a system with a longer PRP.

T

T or F? Color flow Doppler exams tend to have lower temporal resolution than traditional two-dimensional, real time imaging.

T

T or F? Color flow Doppler imaging incorporates pulsed Doppler principles and provides range resolution.

T

T or F? Color flow Doppler systems display anatomical data in grayscale while simultaneously displaying flow information in color.

T

T or F? In diagnostic imaging, it is possible to image with 200 lines/ frame, 15 frames/ second and a maximum imaging depth of 20 cm.

T

T or F? TGC cannot be used with continuous wave Doppler.

T

T or F? The appearance of negative velocities on the spectral display of a continuous wave Doppler exam always indicates that red blood cells are moving away from the transducer.

T

T or F? The primary purpose of demodulation is the preparation of the electrical signal for display on a television.

T

T or F? The sonographer can adjust the receiver gain.

T

T or F? The sonographer can alter the pulser power

T

T or F? Variance mode color maps may be identified by side-to-side changes in the color bar, whereas velocity mode color maps only change color vertically.

T

T or F? Velocity mode color doppler and variance mode color doppler will produce identical images when blood flow patterns are laminar.

T

T or F? With CW doppler frequencies measured at the transducer are produced from many different locations along the ultrasound beam.

T

T or F? With CW doppler the duty cycle of the continuous wave is 100%.

T

T or F? With sector scanning, images with greater detail (spatial resolution) are created when the number of acoustic pulses per degree of sector is increased.

T

T or F? in a pulsed doppler exam, the use of a higher transducer frequency increases the likelihood that aliasing will appear.

T

T or F? the signal to noise ratio remains unchanged when a sonographer adjusts receiver gain.

T

T or F? typically, the sonographer can adjust the threshold level.

T

Which of the following is not associated with turbulent flow? A. parabolic b. eddy c. vortex d. swirling

a

Which of the following is not associated with laminar flow? a. layered b. normal c. aligned d. smooth e. cardiac

e

T or F? typically, the sonographer can adjust the compression function of a receiver.

t