Edelman Chapter 7: Range Equation

In order to create an anatomic image, a sound pulse must

travel to a reflector in the body and return to the transducer

How can we accurately calculate the position of the reflector in the body?

By using the time of journey

The elapsed time from pulse creation to pulse reception. ie. The round trip time of a pulse. This is called? (2 names)

Time of flight AKA Go return time

How are time of flight and depth related? 

They are directly related. The deeper a reflector, the longer it will take the pulse to reach it and return back to the transducer

A more superficial structure will have a _________ time of flight/go return time

shorter

Distance = speed x Time. In regards to distance using this formula will give me:

The total distance traveled (to and back from the reflector)

This equation will give me?

The depth of the reflector. Since we are dividing by 2 we get just the depth of the reflector instead of the total distance traveled

What is the 13 microsecond rule?

For every 1 cm of depth in the body, the ultrasound pulse takes 13 microseconds to go out and come back. (go return time)

What is the formula for depth (cm) using the 13 microsecond rule?

Explain this image

Define PRP

The time from the start of one pulse to the start of another pulse

How is PRP related to the maximum imaging depth

They are directly related. The pulse repetition period determines how deep you can image because you have to wait long enough for echoes from the deepest structures to return before sending the next pulse. Therefore, the longer the PRP (off time) → the deeper structures you can see. The shorter the PRP (off time) → the more superficial structures you can see

PRF is _____________ related to maximum imaging depth

inversely

This following formula can be used to:

calculate the maximum PRF allowed for a given imaging depth. This tells you the fastest you can send pulses without missing echo