Knobology Flashcards
Should you unplug your probe while active?
No
What are presets?
Used to help more closely optimize an image for assumed scanning conditions
What are some 2D controls
- Transducer selection
- Multi hertz
- Harmonics
- Transmit power
- TGC
- Focus
- Depth
- Dynamic range
- Freeze
- Cine loop
- Sector width
- Dual image
- Calculations
What is the Multi hertz function on the Ultrasound machine? 2
- These knobs allow you to change the frequency that you are scanning with without changing probes.
- On most machines this is simply called frequency
What is the harmonics function on a machine?
When harmonics is active the machine will send out a fundamental frequency and receive double that frequency when echo return
When should harmonics be used?
Whenever the penetration allows
Modern day “code harmonics” allows for what?
Excellent penetration with higher frequencies
What does the transmit power knob do?
Adjust the intensity of the ultrasound beam transmitted to the patient
Increasing the intensity on the transmit power knob does what?
Improve the signal to noise ratio (SNR) and enhance sensitivity
Some machines transmit power function will be defaulted to 100% on start up so you can only turn it down. Be aware because what do some machines do?
Some machines may automatically adjust our gains to compensate
What does gain do?
Amplifies all the returned echoes during signal processing and is expressed in decibels
What is a TGC?
A receiver gain that adjusts according to time delay or depth
The TGC is often expressed as what?
A slope where the increase in slope is equal to an increase in amplification
Where is lateral gain functions found?
On some cardiac equipment
What is lateral gain used for?
To compensate for side to side non-uniformities in image brightness due to different pathways
How does lateral gain differ from TGC?
It alters echo intensities from individuals scan lines on the periphery of the image
What does focus do?
Adjusts the depth of near field to improve the lateral resolution at the area of interest
Multiple Foci may be available for a larger field but what happens?
Frame rate is significantly reduced
What does Co-processing do?
Help reduce the impact in frame rate
What does the depth knob do?
Gives the ability to maximize the field of view
As the depth changes what must we do to echo information?
The echo information must be redistributed to fit the monitor
Depth influences what?
The frame rate and line density since the speed of sound is a constant
What is dynamic range?
A form of compression that reduces the number of shades of gray to increase the contrast displayed
When dynamic range is reduced what happens?
Weak echoes and noise are removed from the image
If dynamic range is improperly set it may prevent what?
The visualization of small low- contrast structures
What does the freeze control do?
Stops the transducer from sending out sound
What is Cine loop do?
Gives the operator the ability to evaluate structures frame by frame to acquire the best image
The number of frames stored in Cine loop varies by what?
Machine but is typically in the range of hundreds
What is Cine loop?
System memory which allows for a number of frames to be saved until the image is frozen
What is sector width?
Curved linear and echo probes there is the ability to reduce the field of view by firing fewer scan lines
Why does adjusting sector width do?
Potentially improve the frame rate and may also improve the spatial resolution of the image
What is dual image? And what’s the benefit?
The ability to split the screen. This can be of value when demonstrating certain anatomy or pathology
What is persistences?
Frame averaging
What does persistence help with?
Noise reduction by applying temporal averaging to individual pixels
Increasing the persistence will do what?
Decrease the frame rate and is not used for cardiac applications
With the persistence knob the operator can select the number of frames that are averaged to do what?
Create more consistent images
Different calculations are available where?
programmed for the pre-set relative to the anatomy that is being interrogated
Can we program different calculations for a preset?
Yes
What are some less commonly used tool on most machines?
- Zoom
- Maps
- Video invert
- L/R and T/B invert
- Hidden functions
What does zoom do in an ultrasound?
Magnifies the image
What are the two types of zoom?
- Write zoom
- Read zoom
What is write zoom?
Magnifies the image before it is written to the memory.
What is write zoom associated with?
Improved resolution
What is does read zoom do?
Magnifies the image after the image is committed to the systems memory
What is the maps functions in ultrasound?
A way to redistribute the shades of gray displayed so that emphasis can be given to particular values
What can maps be used in ultrasound?
Brighten all low level echoes but ignore echoes above a threshold or vice versa
When can maps be applied?
Before or after an image is frozen and vary with manufacturers
What is the video invert function?
Images are conventionally displayed with fluid as back and soft tissue as varying shades of gray
What is image invert?
An image can be inverted from top to bottom and left and right
What can be the advantage to image invert?
Interventional procedures to assist the performing physician with the introduction of a needle
What are hidden functions?
Some applications may be hidden as they are not commonly used but can be of value in times of need
What is pre- processing?
Anything that can be done before the image is committed to memory
What is post processing?
Controls are applied to the image after it is frozen
What are some of the more common controls to both spectral and colour doppler? 4
- Gain
- Scale (PRF)
- Steer
- Invert
What is compound imaging? 2
- Combination of beam steering and frame averaging that can improve the SNR and help eliminate artifacts
- Different companies use different trade names for this technology
What is the problem with compounding imaging sometimes?
Some artifacts can be useful in aiding diagnosis this control must be used appropriately
What is considered an appropriated size for the sample volume when performing doppler?
1/3 the size of the lumen
