Pulse-Echo Flashcards
Amplification
Increases the strength of all electrical signals in the receiver prior to further processing
(receiver gain)
Analog
relating to or using signals or information represented by a continuously variable physical quantity such as spatial position or voltage.
Analog to digital conversion
A signal processing operation where the amplified voltage signal representing an ultrasound echo is converted into a binary number.
Beam Former
introduces a set of times delays across the individual elements
Bistable
means the system has two stable equilibrium states. Something that is bistable can be resting in either of two states. These rest states need not be symmetric with respect to stored energy.
Cathode-Ray Tube
a display device
Coded Excitation
creating very long sound pulses containing a wide range of frequencies, distributing energy over a broad frequency range
Compensation
used to make image uniformly bright from top to bottome
Compression
The phase of the wave when the molecules are pushed together
Contrast Resolution
The ability of the imaging system to differentiate between body tissues and display them as different shades of gray.
Demodulation
Retains the actual amplitudes of echo voltages
Depth Gain Compensation
to allow for greater amplification of the weaker echos returning from deeper within the body.
Digital-to-analog converter
an electronic device for converting digital signals to analog form.
Dynamic Range
This allows the range of echoes or shades of gray displayed on the screen to be decreased. This will remove low-level echoes from the display and result in an image with more contrast
Frame Rate
Frame rate= PRF/ lines per frame
Depends upon the PRF and the number of scan lines per image.
Gain
The degree of amplication of the returning echo is called the gain. Echo or signal amplification is necessary because the returning echoes are too weak to be displayed and visualized. Echoes can be strengthened by increasing the intensity of the transmitted signal or by increasing the amplification of the returning signal.
Gray Scale
allow each echoes of varying degrees of amplitude to be displayed within the same image
Image Memory
Stores a number of sequentially acquired and processed static image frames every second which are rapidly sent to the display to provide dynamic real-time ultrasound.
Image Processor
formats the many scan line data into form
Persistence
averaging of sequential frames together to get a smoother image
PACS
Picture archiving and communications system
Pixel
a minute area of illumination on a display screen, one of many from which an image is composed.
Postprocessing
after scan converter memory
Preprocessing
Image processing done before echo data are stored in image memory
Real-time
enabled the visualization of moving structures but also help speed up the examination time.
Real-time Display
several images can be presented per second
Scan Converter
Temporarily stores images during scanning, for viewing and recording
Performs scan conversion, enabling the image data to be viewed on video monitors
Signal Processor
after the images pass through this processor they are fed into the image processor
Spatial Compounding
using sonographic info from several different imaging angles to produce a single image
Only available in phased array transducers.
Temporal resolution
The ability to accurately portray movement occurring within the field of view during real-time imaging.
Time Gain Compensation
This is required in order to compensate for the fact that signals returning from deeper reflectors will be weaker than signals returning from more shallow reflectors, because of attenuation. Increasing TGC amplifies signals more from deeper structures than it does from shallow structures.
