Physics Test Ch. 12 and 13 Flashcards
When the crystals are defective, the entire image is destroyed with this type of transducer
Single crystal transducer. Mechanical transducer Pg 167
Which transducer creates a beam that is focused in all planes and at all depths?
annular phased array
What is the advantage of using a 1 1/2 dimensional array transducer?
Creates thinner beams with improved slice thickness ( or elevational resolution) over a greater range of depths p 190
What type of resolution is improved with a 1 1/2 dimensional array transducer?
Slice thickness and Elevational resolution Pg 188
What is the image shape of a vector array transducer?
Trapezoidal Pg 187
Which transducer has active elements arranged in a straight line?
Linear Pg 168
Which transducer has active elements arranged in circular rings?
Annular Pg 168
Which transducer has active elements arranged in an arched or bowed matter?
Convex Pg168
Phased array always means what?
Adjustable or multi-focused Pg 170
Linear switch transducer has what type of steering technique?
Also called linear sequential. Has electronic steering. Pg 187
What type of probe has dropout lines of image information from top to bottom?
Linear and convex Pg 187
Horizontal or side to side dropout occurs in which transducer type when crystals are bad?
Annular phased array. Pg187
Which transducer is designed to be mechanically steered and fixed with single focus?
Mechanical Pg187
The use of more active elements to receive reflections with a greater time of flight is called
Dynamic aperture? *found on a quizlet
What is the ultrasound machine that can display real time images and Doppler?
Duplex pg 313
The ability to accurately locate moving structures at any time is what kind of resolution?
Temporal resolution Pg 198
What will decrease temporal resolution?
Deeper imaging, which decrease frame rate and degrades temporal resolution Pg 200
Real-time imaging could be referred to as…?
Ultrasound “movie” Pg 197
What determines temporal resolution?
Frame rate Pg 198
What are the factors that limit frame rate?
- speed of sound in the medium
- Imaging depth Pg 198
What will affect the pulses in a single image?
- Number of focal points
- Sector size
- Line density Pg 201
If we double imaging depth, what happens to frame rate?
Frame rate is halved Pg 210
Imaging to greater depth of view requires what?
- Long go-return time
- Longer Tframe
- Lower frame rate
- Inferior temporal resolution Pg 200
What will degrade temporal resolution?
(Lower frame rate)
- Deeper imaging
- Multiple focal points
- Wide sector
- High line density Pg 209
What is the sector size that will use the fewest pulses?
The narrowest sector size p. 204
The sonographer increases line density from 1 line to 3 lines, what will be the consequence of this action?
Temporal resolution decreases p. 211
If the frame rate is 50 Hz, how long does it take to create a frame?
1/50 sec p. 214 (#23 is an example of this)
Lateral resolution improves with what?
Multi-focusing p 209
Low line density creates what?
- widely spaced lines
- fewer pulses per frame
- shorter T frame
- higher frame rate
- high temporal resolution
- poor spatial resolution p. 207 (yellow box)
What creates an image with poor movie quality but high image quality?
- Poor temporal resolution
- Low frame rate Pg 208
Increasing the line density degrades _____ and improves _____.
Degrades temporal resolution and improves spatial resolution p. 207
A critical factor in determining frame rate, line density and imaging depth is?
Time pg 213
If imaging depth is 15 cm and there’s 100 lines… When frame is made quickly…how many Frames created per second?
100 frames per second p. 213
Using a phased array ultrasound system, if you turn off the multi-focus feature what will most likely be a consequence of this action?
Temporal resolution increases pg 211
Which of the following is consistent with increased or improved spatial resolution?
High line density p. 207
When a frame is made quickly, how many frames are created per second?
a lot
When you have 1 frame created in 1/100 second, what is the frame rate?
100 per second or 100 Hz p. 213
What are the different shapes of images for all different probes?
Mechanical - sector Linear sequential - rectangle Phased array - sector Annular phased - sector Convex - blunted sector Vector - trapezoidal
In a linear phased array, what is the firing pattern that steers a beam to the left or right?
Electronic slope
What is apodization?
Stronger electrical signals are used to excite inner crystals, and progressively weaker spikes excite the outer crystals then lobes are diminished p. 193
Focused and unfocused
~
What are side lobes?
sound beams created by single element transducers and are additional areas of sound energy extend outside of the main beam in the far zone
What are grating lobes?
created by array transducers, the extra off-axis sound beams are undesirable because they degrade lateral resolution, reduce image quality, and create artifacts p. 192
What is dynamic aperture?
“transmit hole” or “listening hole” makes sound beam narrow over a greater range of depths improves lateral resolution Pg194
In linear phased arrays, what is the firing pattern that focuses a sound beam?
Electronic curvature
What’s the typical value for the electrical signal delay in a phased array transducer?
4-10 nanoseconds-what seniors had
10 nanoseconds-in book p 172
