Pulse Echo Principles
- A pulse is a group of ultrasound waves that travel together. Each ultrasound pulse has a beginning and an end and has certain characteristics.
- In pulsed ultrasound the same piezoelectric crystal is used to send the ultrasound pulse and receive the returning echoes.
Components of a pulse:
- The transmit time which is also called the on time. During this time the ultrasound machine is on and short bursts of ultrasound pulses are produced and transmitted.
- The receive time which is also called the off time. During this time the returning echo signals are received by the transducer. No sound pulses are produced during this time.
Spatial Pulse Length: the distance from the start of a pulse to the end of that pulse.
- The spatial pulse length is determined by both the source and the medium through which it travels
- Spatial pulse length determines the longitudinal resolution which determines the image quality. Shorter pulses create the higher quality images.
Pulse Duration: the amount of time it takes from the start of a pulse to the end of that pulse. It is the time when the ultrasound system is on and transmitting the ultrasound pulse.