Lesson 2 (Part 1) Flashcards
What kind of instruments are diagnostic US systems?
Pulse echo
What do diagnostic US systems determine? (2)
- Echo strength
2. Location
How is echo strength and location determined? (2)
- Directions
2. Arrival time
What are the 4 main sections of an US instrument?
- Beam former
- Signal processor
- Image processor
- Display
When do we only work with the voltage?
When we are beyond the transducer
What are the instruments of a beam former? (8)
- Master synchronizer
- Pulser
- Pulse delays
- Transmit/receive switch
- T/R switch - Amplifiers
- Analog-to digital converters
- Echo delays
- Summer
What are the components of the transmitter? (4)
- Master synchronizer
- Pulser
- Pulse delays
- Transmit/receive switch
- T/R switch
What are the components of the receiver? (4)
- Amplifiers
- Analog-to digital converters
- Echo delays
- Summer
What kind of voltage do you get when you send echos?
Pulse voltage
- transmission
What kind of voltage do you get when you receive echos?
Echo voltage
- reception
What does the master synchronizer do?
It coordinates the entire system
- tells the pulser when to fire
What does the T/R switch do?
Switches function
How do you prevent range ambiguity artifact?
You wait for the echo to come back before you fire off the next pulse
Range ambiguity artifact
Incorrect placement of an echo along the scan line
- echo misplacement
What does the pulser do?
It produces an electric voltage that drives the transducer
- forms the beam that sweeps through the tissue
Pulse
A single cycle of voltage of desired frequency
What does the frequency of the voltage pulse determine?
The frequency of the resulting US pulse
- f(voltage) = f(pulse) = f (operating)
What units are you using when involved voltages?
MHz
What is the range of frequency for a pulser?
2-20 MHz
PRF
Pulse repetition frequency
Pulse repetition frequency
Is the number of voltage pulses sent out to the transducer each second
What does PRF range for 2D?
4-15kHz
- does this automatically
What does PRF range for doppler?
5-30kHz
- operator-controlled
What does PRF(voltage) equal?
PRF(pulse)
- 1 pulse is produced per 1 voltage
PRP
Pulse repetition period
Pulse repetition period
The time it takes from the beginning of one pulse to the beginning of the next
What does PRP(voltage) equal?
PRP(pulse)
What do you need in order to receive information fast?
A high PRF
What is PRF limited by?
Depth
What is needed for deeper images?
Lower PRF
- takes more time
- decrease frame rate
Frame rate
The number of images that are generated per second
