Physics Test Ch. 14 and 15 Flashcards
Which component of an Ultrasound system is responsible for organization and time?
Master synchronizer Pg 216
Which component of an Ultrasound system creates an electrical signal that excites the PZT?
Pulser Pg 217
The anatomy area of the TGC curve where attenuation occurs
Slope
What part creates the firing pattern for a phased array system?
Beam Former Pg 221
What are all of the receiver functions?
- Amplification
- Compensation
- Compression
- Demodulation
- Reject Pg 223
Acoustic power of a sound beam is determined by what part of a pulser?
Voltage Pg 237
What type of pulser generates constant electrical signal in the form of a sine wave?
Continuous wave Pg 236
What is the function that will improve signal to noise?
increasing output power is the most common way to improve signal to noise pg 219
What is the receiver function that has to do with demodulization?
Rectification Or Smoothing Pg 232
What is the receiver function that keeps ______ within range of the human eye?
Compression Gray scale Pg 230
What is the receiver function that is not adjustable by the sonographer?
Demodulation Pg 232
When an image is too dark or too bright, what are your two options to adjust the image?
output power (if image is too bright) and receiver gain (if image is too dark)
Which receiver function treats signals differently depending on depth?
Compensation Pg 226
What is the receiver function that affects the weak signals, leaving the strong signals unchanged?
Reject Pg 233
Also known as suppression and threshold
When PRP is long, PRF will be? And how does this affect listening?
-Lower
-Longer listening time
Pg 220 (deep imaging)
Know all six components of an ultrasound system
- Transducer
- Pulser and beam former
- Receiver
- Display
- Storage
- Master synchronizer Pg 216
What should you do if an ultrasound system displays reflectors only in the far region?
Adjust the systems compensation pg 238
What is the best choice if the entire image is too bright?
Decrease the output power pg 238
Which component will affect strength of every pulse transmitted into the body?
Amplification Pg 224
What are some disadvantages of analog scan converters?
- image fade
- image flicker
- instability
- deterioration pg 243
Which electronic component is required for gray scale imaging?
Scan converter
Read magnification
Occurs after the image data is stored in the scan converter; displaying original data.
Number of pixels in the image stay the same which makes the pixels larger when zoomed in p250
Temporal resolution may be improved if the region of interest is _____ in comparison to the original?
If the bottom of the region of interest is shallower that the original image’s depth of view pg. 252
Advantages of an analog scan converter
Unlimited and continuous range of values
Real world-numbers that are found in our everyday lives
Spatial resolution is improved because of the large number of storage elements
How many shades of gray are represented by 5 bits
32
22222=32
How many bits are needed to store certain amount of shades of gray.
Example: 10 shades of gray? 11 shades of gray? 15 shades of gray?
Four bits are required to store from 9 to 16 shades of gray
What are the preprocessing functions?
All the changes made to an image before storage.
- time gain compensation
- log compression
- write magnification
- persistence
- spatial compounding
- edge enhancement
- fill in interpolation pg 249
Know about pixels
Smallest building block of a digital picture; number of picture elements per inch
-Low pixel density:
few pixels/inch
larger pixels
less detailed image
lower spatial resolution
-High pixel density:
many pixels/inch
smaller pixels
more detailed image
higher spatial resolution pg. 244Know the diagram on pg. 247 about digital and analog
analog——->analog-to-digital converter ——-> digital memory (zeros and ones) ——-> digital-to-analog converter ——–> analog pg. 247
Bistable imaging
Images are composed of black and white shades only. pg 239
Spatial resolution of the CRT is determined by what? (Beth said “CRT” means “screen/monitor”)
Pixel density Pg. 377
What function is related to the ability for us to see shades of gray?
Compression pg 230
Real world vs. computer world
real world is analog and computer world is digital 242
While scanning, you increase your overall gain. Is this preprocessing or postprocessing?
Preprocessing pg. 249
Preprocessing
The manipulation of image data before storage in the scan converter; sonographer controls this; alters image data forever and cannot be reversed/undone pg. 249
Postprocessing
The manipulation of image data after storage in the scan converter; sonographer controls this; since this occurs after A-to-D conversion and storage, all changes can be reversed; any alterations to a frozen image must be postprocessing
- Any change after freeze frame
- Black/white inversion
- Read magnification
- Contrast variation
- 3-D rendering pg. 249
What portion converts data into numbers?
Digital scan converter Pg. 243
What are the advantages of coded excitation?
- Higher signal-to-noise ratio
- Improved axial resolution
- Improved spatial resolution
- Improved contrast resolution
- Deeper penetration pg. 253
What is fill-in interpolation?
Fill in the gaps of missing data in a way that cannot be detected by the observer; form of preprocessing pg. 257
What is coded excitation? (where does it occur)
Creates very long sound pulses containing a wide range of frquencies. Occurs in the pulser. pg. 253
What is spatial compounding?
Spatial compounding averages multiple frames obtained by steering the sound beam in different directions
What is elastography?
Produces images from sound reflection. Images are relayed to mechanical properties of tissue. Theory of elastography is that tissue will deform differently following the application of a force. Estimates tissue stiffness. pg 258
Which technology reduces speckle and improves spatial resolution?
Spatial compounding pg. 254
What is speckle?
is noise resulting from constructive and destructive interference of small sound wavelets. pg 374
Which technology provides a history of past frames that overlay on the present frames?
temporal compounding, persistence, or temporal averaging pg 256
This type of pulser generates numerous electrical spikes, which ultimately create a single sound pulse
Pulsed wave, phased array p 237
Demodulation
- fourth function of the receiver
- is a two-part process that changes the electrical signals within the receiver into a form more suitable for display on a monitor
when determining receiver gain or output power which should be in the main concern
ALARA/bioeffects
The signal from the transducer to the receiver is what?
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