GETPARAM Parameters of an ultrasound array

GETPARAM returns parameters of a uniform linear or convex array.

Contents



Syntax

PARAM = GETPARAM opens a dialog box which allows you to select a transducer whose parameters are returned in PARAM.

PARAM = GETPARAM(PROBE), where PROBE is a string, returns the prameters of the transducer given by PROBE.

The structure PARAM is used in several functions of MUST (Matlab UltraSound Toolbox). The structure returned by GETPARAM contains only the fields that describe a transducer. Other fields may be required in some MUST functions.

PROBE can be one of the following:

  1. 'L11-5v' (128-element, 7.6-MHz linear array)
  2. 'L12-3v' (192-element, 7.5-MHz linear array)
  3. 'C5-2v' (128-element, 3.6-MHz convex array)
  4. 'P4-2v' (64-element, 2.7-MHz phased array)

These are the Verasonics' tranducers. Feel free to modify the code and complete this list for your own use.

The structure PARAM returned by |GETPARAM|contains the following fields:

  1. PARAM.Nelements: number of elements in the transducer array
  2. PARAM.fc: center frequency (in Hz)
  3. PARAM.pitch: element pitch (in m)
  4. PARAM.width: element width (in m)
  5. PARAM.kerf: kerf width (in m)
  6. PARAM.bandwidth: 6-dB pulse-echo fractional bandwidth (in %)
  7. PARAM.radius: radius of curvature (in m, Inf for a linear array)



PARAM fields from GETPARAM

The PARAM fields returned by GETPARAM have the following values:

  PARAM fields     units      'L11-5V'       'L12-3V'       'C5-2V'       'P4-2V'   
  Nelements - 128 192 128 64
  fc Hz 7.6e6 7.5e6 3.6e6 2.7e6
  pitch m 300e-6 200e-6 508e-6 300e-6
  kerf m 30e-6 30e-6 48e-6 50e-6
  width m 270e-6 170e-6 460e-6 250e-6
  bandwidth % 77 93 80 74
  radius m Inf Inf 49.6e-3 Inf



Example: Generate a focused pressure field

This example shows how to simulate a focused pressure field with a cardiac phased-array.

Download the properties of a 2.7-MHz 64-element cardiac phased array in a structure param by using GETPARAM.

param = getparam('P4-2v');
disp('The properties of the selected probe are:')
disp(param)
The properties of the selected probe are:
           fc: 2700000
         kerf: 5.0000e-05
        width: 2.5000e-04
        pitch: 3.0000e-04
    Nelements: 64
    bandwidth: 74
       radius: Inf

Define the focus position.

x0 = 2e-2; z0 = 5e-2; % in m

Calculate the transmit delays with TXDELAY.

dels = txdelay(x0,z0,param);

Define a 200-by-200 image grid.

x = linspace(-4e-2,4e-2,200);
z = linspace(0,10e-2,200);
[x,z] = meshgrid(x,z);

Simulate the acoustic pressure field and display it.

P = pfield(x,z,dels,param);
imagesc(x(1,:)*1e2,z(:,1)*1e2,20*log10(P/max(P(:))))
hold on
plot(x0*1e2,z0*1e2,'bo','MarkerFaceColor','b')
hold off
colormap hot
axis equal tight
caxis([-20 0])
c = colorbar;
c.YTickLabel{end} = '0 dB';
ylabel('[cm]')
title('A focused field with a cardiac phased-array.')
legend('Focus')
set(gca,'XColor','none','box','off')



See also

txdelay, pfield



About the author

Damien Garcia, Eng., Ph.D.
INSERM researcher
Creatis, University of Lyon, France

websites: BioméCardio, MUST



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