Question

Calculate the PRP, PRF, PD, DF, SPL, wavelength, period, and Axial Resolution if a 2 cycle pulse emitted from a 10 MHz transducer if the echo time received was 0.26 ms in soft tissue.


Part II - Using the information above:

1. If the PRF decreases what happens the DF?

2. If PRP decreases what happens to the PRF?

3. If the frequency increases what happens to the axial resolution (improve or degrade)?

4. If wavelength decreases what happens to the DF?

Answer 1

1. The DF increases: DF = PW/PRF.

2. The PRF increases: PRF = 1/PRP.

4. When WL decreases, the PRF increases.
The increase in PRF decreases the DF.

PRF = V/WL

Answer 2

Part 1:

distance:
Distance - d=ct
Echo time- 10 ms
1540 m/s x .01s = 15.4 m
15.4/2
= 7.7m

PRF:
PRF = c/2D
1540 m/s / (2 x 7.7 m)
=1540 m/s / 15.4 m
=100 s

PRP:
PRP = 1/PRF
1/100 HZ
= .01s

Period:
Period - T= 1/f
1/5 MHZ
=.2 us

PD:
PD= nT
3 cycles x .2 us
= .6 us

DF:
DF= PD/PRP
.6us = .0000006 s
.0000006 s / .01s
=.00006
= .006%

wavelength:
Wavelength=c/f
1540m/s / 5 MHZ
1540 m/s / 5,000,000 1/s
.000308
= .308 mm

SPL:
SPL=nw
3 x .308 mm
= .92 mm