US Physics

Question 1

SPL

Answer 1

spatial pulse length.
- the measurement of the pulse from front to back
wavelength (length of each cycle) X the no. of cycles in the pulse
measured in: mm

Question 2

PRF

Answer 2

pulse repetition frequency.
- measurement of the no. of pulses that occur in 1 second.
measured in: kHz

Question 3

what exactly does the pulse repetition frequency do?

Answer 3

the US machine sends out a pulse that forms a beam pathway, then the echoes return to the probe along the same path. This pattern is repeated rapidly and forms an image.

Question 4

what is the limitation for PRF?

Answer 4

in real time US scanning, the images are required to be created rapidly but the machine can’t send out another pulse before all the information from the previous pulse has come back.
This means that it is limited by the time it takes for the sound to travel through the patient to the reflector and then come back to the transducer.

Question 5

PRP

Answer 5

pulse repetition period.
- this is the time from the beginning of one pulse to the beginning of the next.
measured in: time (ms)

Question 6

What happens to the PRF when the PRP decreases?

Answer 6

The PRF increases. This happens bc when more pulses occur in a second, the time bw them decreases.

Question 7

PD

Answer 7

pulse duration. It is the time each sequence of pulses is on for. no. of cycles X by the period. Measured in time (µs).

Question 8

DF

Answer 8

duty factor. It is the fraction of time that the pulsed US is on, in a ratio (decimal or percentage)

Question 9

Pulse Echo Principle

Answer 9

is the distance between the probe & echoing structure. To find this you first need to measure the time bw the transmission pulse & receiving back each echo, then you can measure the distance bw the probe and structure.

Question 10

round path distance

Answer 10

the distance travelled from probe to the detector & back to the probe