Physics Chapter 13

T or F. If 100 scan lines make up an image and the frame rate is 30 per second, then the transducers frequency is 3,000 Hz

False. A transducers frequency is independent of the characteristics of the image that it creates

T or F. The number of lines per frame and the frame rate determine the frequency

False. determines the PRF

T or F. If the imaging depth of a scan is 15 cm and there are 100 lines in the image, then the number of pulses making up the scan is 1500.

False. if the imaging depth of a scan is 15cm and there are 100 lines in the image, then the number of pulses making up the scan is 100

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

False. temporal resolution of a system is unaffected by the pulse duration

T or F. The critical factor in determining frame rate, line density, and imaging depth is the transducer style

False. the critical factor in determining frame rate, line density, and imaging depth is time

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

B.

T or F. If 100 scan lines make up an image and the frame rate is 30 per second, then the systems pulse repetition frequency is 3,000 Hz

True

T or F. If the imaging depth of a scan is 15cm and there are 100 lines in the image, then the number of pulses making up the scan is 100

True

T or F. the length of a pulse does not directly influence the temporal resolution

True

T or F. the number of lines per frame and the frame rate determine the PRF

True

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

True

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.

True

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

D.

A sonographer reduces sector angle from 90 degrees to 30 degrees. At the same time, the ultrasound system automatically increases the line density from 1 line per degree to 2 lines per degree. No other changes are made. What will happen to the frame rate? A. increases B. decreases C. remains unchanged

A. Frame rate will increase

Which of the following is most important in determining the frame rate if a system? A. depth of view B. dynamic range of the receiver C. transducer frequency D. transmitter output

A. of these choices, depth of view is the most important factor in determining frame rate

A sonographer adjusts an ultrasound machine to change the sector size from 90 to 45 degrees. Nothing else changes. What happens to the frame rate? A. it is doubled B. it remains unchanged C. it is halved D. it is tripled

A. The frame rate is doubled since fewer pulses are needed to make the image

Which two factors determine temporal resolution? A. speed of sound and depth of view B. pixel size and sector shape C. focal zones and sector depth D. propagation speed and frame rate

A. has the greatest effect upon frame rate and temporal resolution

Which of the following is most important in determining the frame rate of a system? A. speed of sound in the medium B. dynamic range of the receiver C. transducer frequency D. transmitter output

A. of these choices, speed of sound in a medium is the most important factor in determining frame rate

A sonographer adjusts an ultrasound scan to double the depth of view from 5cm to 10cm. What happens to the frame rate? A. it is halved B. it doubles C. it increases from 5 to 10 Hz D. it is unchanged

A. the frame rate will be halved. Frame rate and imaging depth are inversely related

What is the fundamental limitation of temporal resolution A. imaging depth B. speed of sound in the medium C. line density D. sector size

B

A sonographer increases the line density from 1 line per degree of sector to 3 lines per degree of sector. What is the most likely consequences of this action? A. frame rate increases B. temporal resolution decreases C. imaging quality decreases D. temporal resolution increases

B. temporal resolution decreases. Increasing line density from 1 to 3 lines per degree triples the number of pulses in each image

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. with multiple foci along each scan lines, the ultrasound system uses many pulses to create each image. This reduces the number of frames created per second. A low frame rate results in decreased temporal resolution

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

An ultrasound system with a 4.0 MHz transducer is used to image structures as deep as 15cm. Twenty images are produced each second, each requiring 100 acoustic pulses. What is the PRF of the system? A. 1,500 Hz B. 300 Hz C. 2,000 Hz D. 4 MHz

C

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

C

Under certain conditions, an ultrasound system creates each image in 0.01 seconds. What is the frame rate? A. 1 Hz B. 10 sec C. 100 Hz D. 200 Hz E. 0.02 Hz

C

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

C

Which of the following sector imaging systems will have the best image detail if all other parameters are identical? A. 90 degree sector with 100 pulses/images B. 80 degree sector with 40 pulses/images C. 70 degree sector with 84 pulses/images D. 60 degree sector with 60 pulses/images

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.

What is the time needed to make a single image if the frame rate of ultrasound system is 20 Hz? a) 1 s b) 0.02 s c) 0.05 s d) 15 Hz

C. Tframe multiplied by the frame rate equals 1. if 20 frames are created each second, then Tframe is 1/20 or 0.05sec

A sonographer adjusts an ultrasound system to change the sector size from 90 to 45 degrees. The frame rate was unchanged. What else must have happened? A. temporal resolution was doubled B. sector size was doubled C. line density was doubled D. imaging depth was halved

C. Since the frame rate is unchanged, the number of pulses per frame rate was also unchanged. If the sector size is reduced, some other factor must increase the number of pulses per image

A sonographer reduces the sector angle from 90 degrees to 30 degrees. At the same time, the ultrasound system automatically increases the line density from 1 line per degree to 3 lines per degree. No other changes are made. What will happen to temporal resolution? a. increases b. decreases c. remains unchanged

C. Temporal resolution is unchanged

What is the frame rate if each image of the ultrasound system is created in 0.02 sec (1/50 sec)? A. 20 Hz B. 100 Hz C. 50 Hz D. 15 Hz

C. frame rate and Tframe are reciprocals.

Which of the following forms of resolution improve when frame rate increases? A. lateral B. longitudinal C. temporal D. spatial resolution

C. temporal resolution is directly related to frame rate. Higher frame rates improve temporal resolution

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

D

When the frame rate is 30 Hz, how long does it take to create a frame? A. 30 sec B. 3 sec C. 0.3 sec D. 1/30 sec E. 1/3 sec

D

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

D

A sonographer adjusts an ultrasound scan to double the depth of view from 5cm to 10cm. If the frame rate remains the same, which one of the following also occurs? A. increased line density B. wider sector C. multi-focus imaging turned on D. narrower sector

D. Narrower Sector

Which of the following is consistent with improved temporal resolution? A. color Doppler B. more gray shades C. more detail D. higher frame rate

D. frame rate determines temporal resolution. High frame rates results in improved temporal resolution

A sonographer, using a phased array ultrasound system, turns off the multi-focus feature. What is most likely consequences of this action? A. frame rate decreases B. temporal resolution degrades C. imaging depth increases D. temporal resolution improves

D. Temporal resolution increases. Changing multi-focus to single focus reduces the number of sound pulses required to make each image

All of the following decrease temporal resolution except: A. lower frame rate B. deeper imaging C. multi-focus D. narrower sector

D. Unlike the other choices, narrow sectors actually improve temporal resolution. Narrow sector images are created with fewer pulses than wide sector images

Two imaging systems produce acoustic pulses; one pulse is 0.4 usec long and the other is 0.2 usec long. Which is most likely to provide the best temporal resolution? A. 0.4 usec system B. 0.2 usec system C. they are the same D. cannot be determined

D. temporal resolution is unrelated to pulse duration. Temporal resolution is determined by the number of frames, or images, that are produced each second. There is insufficient info to answer the question