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load_dicom.m
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load_dicom.m
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% BRAVEHEART - Open source software for electrocardiographic and vectorcardiographic analysis
% load_dicom.m -- Load DICOM ECG Format (requires image processing toolbox)
% Copyright 2016-2024 Hans F. Stabenau and Jonathan W. Waks
%
% Source code/executables: https://github.com/BIVectors/BRAVEHEART
% Contact: [email protected]
%
% BRAVEHEART is free software: you can redistribute it and/or modify it under the terms of the GNU
% General Public License as published by the Free Software Foundation, either version 3 of the License,
% or (at your option) any later version.
%
% BRAVEHEART is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
% without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
% See the GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License along with this program.
% If not, see <https://www.gnu.org/licenses/>.
%
% This software is for research purposes only and is not intended to diagnose or treat any disease.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function [hz, I, II, III, avR, avF, avL, V1, V2, V3, V4, V5, V6] = ...
load_dicom(filename)
% Load DICOM file
D = dicominfo(filename);
% Pull out waveform part of DICOM and the field names in that part of DICOM
ws_fn = fieldnames(D.WaveformSequence);
% Check if there is more than 1 'Item' if there are rhythm strips and medians
% Format requires that there are between 1 and 4 'Items'
% see https://www.dicomstandard.org/News-dir/ftsup/docs/sups/sup30.pdf
len_ws_fn = length(ws_fn);
itemN = 0;
% Only take the RHYTHM data, although could modify to get other types of waveforms if needed
for i = 1:length(len_ws_fn)
if strcmp(string(D.WaveformSequence.(ws_fn{i}).MultiplexGroupLabel),"RHYTHM")
itemN = i;
break;
end
end
% Check that found a RHYTHM waveform
if itemN == 0
error('load_dicom.m: Didnt find a RHYTHM WaveformSequence')
end
% Choose the RHYTHM Waveforms
ws = D.WaveformSequence.(ws_fn{itemN});
waveform = ws.WaveformData;
% Sample frequency
hz = ws.SamplingFrequency;
num_leads = int32(ws.NumberOfWaveformChannels);
num_samples = int32(ws.NumberOfWaveformSamples);
% Details on each of the 12 leads
ch_def = ws.ChannelDefinitionSequence;
ch_def_fn = fieldnames(ch_def);
mcv_perunit = zeros(1,num_leads); % MICROVOLTS (convert to millivolts later)
baseline = zeros(1,num_leads);
correction = zeros(1,num_leads);
% obtain data on each lead
for i = 1:num_leads
mcv_perunit(i) = ch_def.(ch_def_fn{i}).ChannelSensitivity;
baseline(i) = ch_def.(ch_def_fn{i}).ChannelBaseline;
correction(i) = ch_def.(ch_def_fn{i}).ChannelSensitivityCorrectionFactor;
lead_str{i} = ch_def.(ch_def_fn{i}).ChannelSourceSequence.Item_1.CodeMeaning;
end
% Convert into int16 based on whatever encoding DICOM using
% Get encoding
E = string(class(ws.WaveformData));
if strcmp(E, 'uint16')
% Convert uint16 to int16
fullsignal = double(typecast(uint16(waveform), 'int16'));
elseif strcmp(E, 'uint8')
% Convert uint8 to int16
fullsignal = double(typecast(uint8(waveform), 'int16'));
elseif strcmp(E, 'int16')
fullsignal = waveform;
else
error('Check WaveformSequence.Item_N.WaveformData encoding - may need to add current encoding to load_dicom.m')
end
% get each lead out of the singla waveform
L = zeros(num_leads, num_samples);
for s = 1:num_leads
for i = 1:num_samples
L(s,i) = (((fullsignal(s + (12*(i-1)))) + baseline(s)) * (mcv_perunit(s)/1000 * correction(s)));
end
% Read lead_str to determine which lead it is
% Now will not break if the lead labels are not exactly "Lead x"
% But to avoid missing lead II and III had to change order of cases
switch true
case strfind(string(lead_str(s)),'Lead III') == 1
III = L(s,:);
case strfind(string(lead_str(s)),'Lead II') == 1
II = L(s,:);
case strfind(string(lead_str(s)),'Lead I') == 1
I = L(s,:);
case strfind(string(lead_str(s)),'Lead aVR') == 1
avR = L(s,:);
case strfind(string(lead_str(s)),'Lead aVL') == 1
avL = L(s,:);
case strfind(string(lead_str(s)),'Lead aVF') == 1
avF = L(s,:);
case strfind(string(lead_str(s)),'Lead V1') == 1
V1 = L(s,:);
case strfind(string(lead_str(s)),'Lead V2') == 1
V2 = L(s,:);
case strfind(string(lead_str(s)),'Lead V3') == 1
V3 = L(s,:);
case strfind(string(lead_str(s)),'Lead V4') == 1
V4 = L(s,:);
case strfind(string(lead_str(s)),'Lead V5') == 1
V5 = L(s,:);
case strfind(string(lead_str(s)),'Lead V6') == 1
V6 = L(s,:);
end
end
% Signal is now in MILLIVOLTS