Field II Exercise

Wednesday, May 22, 13.00-15.00 on the top floor in build 349, room 205.

Purpose:

This exercise will teach how to simulate point spread functions using Field-II, as well as how to simulate linear array imaging.

Preparation:

Download Field-II, along with the user-guide. Study the section/slides on beamforming in the course notes.

Exercise:

1. Define a linear array transducer with the following properties:
   
   

   Parameter	Content	Unit
   Elements	128
   Active elements	64
   Center frequency f0	7	MHz
   Pitch	λ
   Element height	5	mm
   Kerf	λ/20
   Electronic focus	40	mm
   Excitation	1 cycle at f0
   Impulse response	2 cycles Hanning weighted
   Apodization	Hamming

   
   
2. Use the linear array transducer with a one cycle excitation at the center frequency. You should use 64 active elements in transmit with a Hamming apodization and one pitch between image lines for a linear array scan.
3. Calculate the point spread function for the emitted field at 30, 40, and 60 mm from the transducer surface and show contour plots of the envelope of the emitted pressure with 6 dB between contours.
4. Vary the electronic focus and observe the change in the point spread function.
5. Define a point phantom with scatterers for every 10 mm from 5 to 100 mm from the transducer
6. Simulate a linear image of the point phantom with a line spacing in the image of $\lambda$. Make an image with 65 lines in it of the wires with a dynamic range of 60 dB.
7. Make a cyst phantom with a single cyst. It must have a radius of 5 mm. The size of the phantom should be 15 x 15 x 5 mm (axial x lateral x elevation) and it should contain 10,000 scatterers.
8. Simulate a linear image of the cyst phantom with a line spacing in the image of $\lambda$. Make an image of the cyst with a dynamic range of 60 dB.