Resolution of Delay Multiply And Sum on FI data from an UFF file

by Ole Marius Hoel Rindal olemarius@olemarius.net 28.05.2017

Contents

Setting up file path

To read data from a UFF file the first we need is, you guessed it, a UFF file. We check if it is on the current path and download it from the USTB websever.

close all;

% data location
url='http://ustb.no/datasets/';      % if not found downloaded from here
local_path = [ustb_path(),'/data/']; % location of example data


% Choose dataset
filename='Alpinion_L3-8_FI_hyperechoic_scatterers.uff';

% check if the file is available in the local path or downloads otherwise
tools.download(filename, url, local_path);

Reading channel data from UFF file

channel_data=uff.read_object([local_path filename],'/channel_data');
% Check that the user have the correct version of the dataset
if(strcmp(channel_data.version{1},'1.0.2')~=1)
    error(['Wrong version of the dataset. Please delete ',local_path,...
                                        filename,' and rerun script.']);
end

UFF: reading channel_data [uff.channel_data]
UFF: reading sequence [uff.wave] [====================] 100%

%Print info about the dataset
channel_data.print_authorship

Name: 		 FI dataset of hyperechoic cyst and points  
		 scatterers recorded on an Alpinion scanner with a  
		 L3-8 Probe from a CIRS General Purpose Ultrasound  
		 Phantom 
Reference: 	 www.ultrasoundtoolbox.com 
Author(s): 	 Ole Marius Hoel Rindal <olemarius@olemarius.net> 
		 Muyinatu Lediju Bell <mledijubell@jhu.edu> 
Version: 	 1.0.2 

Define Scan

Define the image coordinates we want to beamform in the scan object. Notice that we need to use quite a lot of samples in the z-direction. This is because the DMAS creates an "artificial" second harmonic signal, so we need high enough sampling frequency in the image to get a second harmonic signal.

z_axis=linspace(25e-3,45e-3,1024).';
x_axis=zeros(channel_data.N_waves,1);
for n=1:channel_data.N_waves
    x_axis(n) = channel_data.sequence(n).source.x;
end

scan=uff.linear_scan('x_axis',x_axis,'z_axis',z_axis);

Set up the processing pipeline

pipe=pipeline();
pipe.channel_data=channel_data;
pipe.scan=scan;

pipe.transmit_apodization.window=uff.window.scanline;

pipe.receive_apodization.window=uff.window.none;
pipe.receive_apodization.f_number=1.7;

Define the DAS beamformer

das = midprocess.das();
%Sum only on transmit, so that we can do DMAS on receice
das.dimension = dimension.transmit();

Create the DMAS image using the delay_multiply_and_sum postprocess

dmas = postprocess.delay_multiply_and_sum();
dmas.dimension = dimension.receive;
dmas.channel_data = channel_data;
dmas.receive_apodization = pipe.receive_apodization;

b_data_dmas=pipe.go({das dmas});

% beamforming
b_data_dmas.plot(100,'DMAS');

USTB General beamformer MEX v1.1.2 .............done!
uff.apodization: Inputs and outputs are unchanged. Skipping process.

f_stop =

  single

    10913708

Beamform DAS image

Notice that I redefine the beamformer to summing on both transmit and receive.

das.dimension = dimension.both();

b_data_das=pipe.go({das});
b_data_das.plot([],'DAS');

uff.apodization: Inputs and outputs are unchanged. Skipping process.
uff.apodization: Inputs and outputs are unchanged. Skipping process.
USTB General beamformer MEX v1.1.2 .............done!

Plot both images in same plot

Plot both in same plot with connected axes, try to zoom!

f3 = figure(3);clf
b_data_dmas.plot(subplot(2,1,1),'DMAS'); % Display image
ax(1) = gca;
b_data_das.plot(subplot(2,1,2),'DAS'); % Display image
ax(2) = gca;
linkaxes(ax);

Compare resolution

Plot the lateral line through some of the scatterers

% Let's get the images as a N_z_axis x N_x_axis image
dmas_img = b_data_dmas.get_image();
das_img = b_data_das.get_image();

So that we can plot the line through the group of scatterers

line_idx = 250;
figure(4);clf;
plot(b_data_dmas.scan.x_axis*10^3,dmas_img(line_idx,:),...
                               'DisplayName','DMAS','LineWidth',2);hold on;
plot(b_data_das.scan.x_axis*10^3,das_img(line_idx,:),...
                               'DisplayName','DAS','LineWidth',2);
xlabel('x [mm]');xlim([0 20]);ylabel('Amplitude [dB]');legend show
title(sprintf('Lateral line through %.2f mm',...
                                  b_data_dmas.scan.z_axis(line_idx)*10^3));

%So that we can plot the line through the aingle scatterer
line_idx = 747;
figure(5);clf;
plot(b_data_dmas.scan.x_axis*10^3,dmas_img(line_idx,:),...
                                'DisplayName','DMAS','LineWidth',2);hold on;
plot(b_data_das.scan.x_axis*10^3,das_img(line_idx,:),...
                                'DisplayName','DAS','LineWidth',2);
xlabel('x [mm]');xlim([-15 5]);ylabel('Amplitude [dB]');legend show
title(sprintf('Lateral line through %.2f mm',...
                                  b_data_dmas.scan.z_axis(line_idx)*10^3));

Published with MATLAB® R2020b