Chapter 14 Flashcards
Pulsed Echo Instrumentation
What is an ultrasound system?
A highly sophisticated device that creates sound pulses, retrieves the reflections, and produces images and audio signals from these reflections.
The ultrasound system has two major functions:
- Preparation and transmission of electrical signals
- Reception of electrical signals
What are the seven major components of an ultrasound system (in order)?
Transducer
Pulser
Beam Former
Receiver
Display
Storage
Master Synchronizer
The ____ transmits electrical energy into acoustic energy and converts acoustic energy into electrical energy.
Transducer
The ____ creates electrical signals that excite the transducer’s PZT crystals.
Pulser
The pulser determines the ____, ____, and ____.
Amplitude, pulse repetition period, and pulse repetition frequency.
What functions during transmission?
The pulser
The sonographer can adjust the ____ of the electrical voltage spike
Magnitude
Changes in pulser ____ adjust the brightness of the entire image.
Voltage
Two measurements that are related to transducer output (acoustic power) and measure bioeffects are:
- Thermal Index (TI)
- Mechanical Index (MI)
____ is a random and persistent disturbance that obscures or reduces the clarity of the image.
Noise
Signal-to-Noise ratio is the comparison of ____ ____ (signal) to ____ (noise)
Meaningful information; Contamination
With high signal-to-noise ratio the signal is ____ than the noise.
Stronger
With low signal-to-noise ratio, the signal is ____ to the strength of the noise
Close
Increasing the output power will ____ the signal-to-noise ratio (good).
Increase
Increasing the ____ ____ is the only way to improve the signal-to-noise ratio
Output power
The sonographer controls the PRP and PRF by adjusting the ____ ____ ____
Depth of view
The ____ ____ is the part of the transmitter that controls the electrical signals.
Beam former
The beam former determines the ____ ____ ____ for phased array systems.
Firing delay pattern
The ____ ____ receives the single electrical spike from the pulser, and distributes it to all the active elements of an array transducer.
Beam former
True or false: The beam former functions during transmission and reception.
True
During transmission, the beam former reduces lobe artifacts through ____.
Apodization
During reception, the beam former controls ____ ____ by varying the number of PZT crystals used during reception.
Dynamic aperture
What is used in the most modern ultrasound systems to produce signals in digital format?
Digital beam formers