defaultalt Field II home page
Point spread function Field II Simulation Program
    Main page
Center for Fast
Ultrasound Imaging
Biomedical Engineering
Group
JAJ

Background
information

Menu Line
Download
Menu Line
Users guide
Menu Line
Faq
Menu Line
Papers
Menu Line
Examples
Menu Line
   Logo
   PSF
   Intensity
   Cyst phantom
   Kidney phantom
   Fetus phantom
   PW example
   Flow example
   CFM example
   Tissue motion
Menu Line
Copyright
Menu Line
News
Menu Line

Field IIpro

Menu Line

Site

Menu Line


Calculation of the point spread function


The calculation of point spread functions is done by placing a point in front of the transducer and then sweeping the beam over the point. This gives the point spread function of the imaging system. This example calculates the point spread function for a concave, round transducer with a radius of 8 mm, a geometric focus at 80 mm and a center frequency of 3 MHz.

The scanning with such a transducer is done by moving the transducer relative to the tissue. Field II does not have the capability of moving the aperture, so the point is moved instead. The point is moved from -10 mm laterally in steps of 0.2 mm til +10 mm at a distance of 30 mm to the aperture.

The envelope of the responses is then found and it is log compressed to a dynamic range of 60 dB. A mesh plot as the one shown below is then produced.



Point spread function for concave transducer in near field

The m-file for calculating the images can be found at:

examples/ftp_files/logo

The routine field.m initializes the field system, and should be modified to point to the directory holding the Field II code and m-files. The routine concave_logo.m is then called to calculate the point spread function and make the plot.


/examples/logo_example/logo_example.html
Last updated: 23:20 on Wed, 02-May-2012