Pulsed Sound Chapter 3 Flashcards
In diagnostic imaging, what is required to create an anatomic images?
Short pulses of acoustic energy
What is a pulse?
A collection of cycles that travel together
What are the two components of pulsed ultrasound?
on/transmit time and dead/off time
What are the 5 additional parameters that describe pulsed sound?
Pulse duration, pulse repetition period, PRF, duty factor, spatial pulse length
What is pulse duration? Units? Sound source? Can it be changed? Typical values? Equation?
The actual time form the start to end of a pulse aka the talking time. Time (sec). Sound source. No, characteristic of each transducer. 0.5 to 0.3 microsecs. Pulse duration (us) = # cycles in pulse x period (us).
What is spatial pulse length? Units? Determined by? Can it be changed? Typical values? Equation? How does this affect the image?
The distance or length from the start to end of one pulse. Distance (mm). Both the source and the medium, bc wavelength is also determined by both the source and medium. No. 0.1 to 1 mm. =# of cycles x wavelength (mm). Affects image quality (axial resolution) - shorter pulses=higher quality images.
What is pulse repetition period? Units? Determined by? Can it be changed? Typical values? How does it affect the image?
PRP is the time from the start of one pulse to the start of the next, included one pulse duration + one dead time. Time (sec). Sound source. Yes, PRP is determined by imaging depth. 100us to 1 ms. As PR increases, imaging depth increases.