Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
57 Cards in this Set
- Front
- Back
Displaying 2D images one image at a time is called what?
|
Static Scanning
|
|
The ability of the system to create multiple frames each second is called what?
|
Frame Rate
|
|
What two factors determine frame rate?
|
1) speed of sound in the medium (1.54 km/s, CONSTANT)
2) depth |
|
FRAME RATE: Units?
|
Hertz / Images per second
|
|
Accuracy in time, or the ability to precisely position moving structures from instant to instant, is called what?
|
Temporal Resolution
|
|
What is the relationship between frame rate and temporal resolution?
|
Related (high FR improves TR, low FR decreases TR)
|
|
TEMPORAL RESOLUTION: Units?
|
Herz / per second
|
|
What is the relationship between frame rate and the time required to make a single image, or T(frame)?
|
Inversely Related
Reciprocals |
|
What are two sonographer controlled settings which affect frame rate?
|
1) Depth
2) # Pulses/Frame |
|
Waht is the relationship between imaging depth and frame rate?
|
Inversely Related
|
|
Identify the type of imaging:
- short go-return time - shorter T(frame) - higher frame rate - superior temporal resolution |
Shallow Imaging
|
|
Identify the type of imaging:
- long go-return time - longer T(frame) - lower frame rate - inferior temporal resolution |
Deep Imaging
|
|
What is the relationship between frame rate and pulses per frame?
|
Inversely Related
|
|
What three factors determine the number of pulses needed to create and image?
|
1) # Pulses/Scan Line (multi- vs single focus)
2) Sector Size 3) Line Density (lines per angle of sector) |
|
How many sound pulses are transmitted down each scan line when the system is set to single focus?
|
One
|
|
When a sonographer activates multi-focus, what change occurs (versus a single-focus)?
|
More than one sound pulse is transmitted down each scan line.
- Frame rate decreases - Temporal resolution lowers |
|
What type of focus has been selected:
- inferior lateral resolution - superior temporal resolution - higher frame rate - shorter T(frame) - one pulse per scan line |
Single-Focus
|
|
What type of focus has been selected:
- superior lateral resolution - inferior temporal resolution - lower frame rate - longer T(frame) - many pulses per scan line |
Multi-Focus
|
|
What is the main advantage of multiple focal zones?
|
Superior Lateral Resolution
|
|
What is the field of view called?
|
Sector Size
|
|
What is the relationship between frame rate and sector size?
|
Inversely Related
|
|
Identify the sector size:
- superior temporal resolution - higher frame rate - shorter T(frame) - fewer pulses per frame |
Narrow Sector Size
|
|
Identify the sector size:
- inferior temporal resolution - lower frame rate - longer T(frame) - more pulses per frame |
Wide Sector Size
|
|
What is the spacing between sound beams in a sector called?
|
Line Density
|
|
What is the relationship between frame rate and line density?
|
Inversely Related
|
|
Identify the line density setting:
- inferior spatial resolution - superior temporal resolution - higher frame rate - shorter T(frame) - fewer pulses per frame - widely spaced lines |
Low Line Density
|
|
Identify the line density setting:
- superior spatial resolution - inferior temporal resolution - lower frame rate - longer T(frame) - more pulses per frame - tightly packed lines |
High Line Density
|
|
What is the main advantage of high line density?
|
Improved Spacial Resolution
|
|
How are temporal resolution and image quality related?
|
Settings which make for excellent static images will not capture quality motion images (and vice versa)
|
|
The following will have what effect on temporal resolution?
- shallow imaging - single focus - narrow sector - low line density |
Better Temporal Resolution
(higher frame rate) |
|
The following will have what effect on temporal resolution?
- deep imaging - multi-focus (lateral resolution +) - wide sector - high line density (spatial resolution +) |
Worse Temporal Resolution
(lower frame rate) |
|
What can we change to improve lateral resolution?
|
Add (or increase) multi-focus
|
|
What can we change to improve spatial resolution?
|
Increase line density
|
|
Which form of resolution improves when the frame rate increases?
|
Temporal Resolution
|
|
Which of the following is consistent with improved temporal resolution?
A. color Doppler B. more grey shades C. more detail D. higher frame rate |
D. High frame rates (lower Tframe) result in improved temporal resolution
|
|
All of the following decrease temporal resolution except:
A. lower frame rate B. deeper imaging C. multi-focus D. narrower sector |
D. Narrower sectors improve temporal resolution
|
|
A sonographer adjusts an ultrasound scan to double the depth of view from 5 cm to 10 cm. What happens to the frame rate?
|
Frame rate will be reduced by half, due to the inverse relationship
|
|
A sonographer adjusts an ultrasound scan to double the depth of view from 5cm to 10 cm. 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. Since the imaging depth increased, something else decreased in order to maintain the frame rate. Narrower sector is the only choice that creates images in less time.
|
|
A sonographer changes the sector size from 90 to 45 degrees. Nothing else changes. What happens to the frame rate?
|
Frame rate doubles since fewer pulses are needed to create the image
|
|
A sonographer changes 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. If sector size was reduced, something must increase the number of pulses/image. The only answer that does this is doubling line density
|
|
A sonographer, using a phased array system, turns off the multi-focus feature. What is the most likely consequence of this action?
A. frame rate decreases B. temporal resolution degrades C. imaging depth increases D. temporal resolution improves |
D
|
|
A sonographer increases the line density from 1 line/degree of sector to 3. What is the most likely consequence?
A. frame rate increases B. temporal resolution decreases C. imaging quality decreases D. temporal resolution increases |
B
|
|
A sonographeer reduces the sector angle from 90 degrees to 30. At the same time, the system automaticall increases the line density from 1 line/degree to 2. No other changes are made. What will happen to the frame rate?
|
Frame rate will increase
|
|
A sonographer reduces the sector angle from 90 degrees to 30. At the same time, the system automatically increases the line density from 1 line/degree to 3. No other changes are made. What will happen to temporal resolution?
|
Temporal resolution remains unchanged
|
|
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 |
Of these choices, A
|
|
Which of the following is most important in determining the frame rate of a system?
A. dynamic range of the receiver B. depth of view C. transducer frequency D. transmitter output |
Of these choices, B
|
|
What is the frame rate if each image is created in 0.02 sec (1/50 sec)?
|
50 Hz
(since Tframe and frame rate are reciprocals) |
|
What is the time needed to make a single image if the frame rate is 20 Hz?
|
1/20 sec OR 0.05 sec
(since frame rate & Tframe are reciprocals) |
|
T/F: The critical factor in determining frame rate, line density, and imaging depth is the transucer style
|
False. The critical factor is time.
|
|
T/F: the number of lines per frame and the frame rate determine the frequency
|
False. They determine the pulse repitition frequency
|
|
T/F: The number of lines per frame and the frame rate determine the pulse repitition frequency
|
True
|
|
T/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. 100 pulses
|
|
T/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 100
|
True
|
|
T/F: If 100 scan lines make up an image and the frame rate is 30/sec, then the transucer's frequency is 3000 Hz
|
False. Transducer's frequency is independent of the characteristics of the image that it creates
|
|
T/F: If 100 scan lines make up an image and the frame rate is 20/sec, then the system's pulse repetition frequency is 3000 Hz
|
True
|
|
When the frame rate is 30 Hz, how long does it take to create a frame?
|
1/30 sec
(since frame rate and Tframe are reciprocals) |
|
Under certain conditions, the system creates each image in 0.01 sec. What is the frame rate?
|
100 Hz
(since frame rate and Tframe are reciprocals) |