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ss_save_dyn.m
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function ss_save_dyn(g,rf,ang,thk, isodelay, format, fspec, a_angs, root_fname, pulse_num)
% SS_SAVE - Save spectral-spatial pulse
% Uses Chuck Cunningham's format for GE systems, and creates associated
% .dat-file
% Pulse parameters saved in header for Varian fules
%
% ss_save_dyn(g,rf,ang,thk, format, fspec, a_angs, root_fname, pulse_num)
%
% g - in G/cm
% rf - in G
% ang - flip angle in radians
% thk - thickness in cm
% isodelay (optional) - delay from in-phase point to end of pulse (GE
% definition)
% format (optional) - 'GE' (default), 'Varian'
% fspec (optional) - frequency bands (Hz) to write in file
% a_angs (optional) - band amplidutes (radians) to write in file
% root_fname - root file name (no prompting)
% pulse_num - pulse number
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Spectral-Spatial RF Pulse Design for MRI and MRSI MATLAB Package
%
% Authors: Adam B. Kerr and Peder E. Z. Larson
%
% (c)2007-2011 Board of Trustees, Leland Stanford Junior University and
% The Regents of the University of California.
% All Rights Reserved.
%
% Please see the Copyright_Information and README files included with this
% package. All works derived from this package must be properly cited.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ss_globals;
if (nargin < 5) || isempty(isodelay)
isodelay = length(rf)*SS_TS/ 2;
end
if (nargin < 6) || isempty(format)
format = 'GE';
else
switch format,
case {'GE', 'Varian'}
otherwise
error(sprintf(['Format save type of: %s not' ...
' recognized'], format));
end;
end
maxg = max(abs(g));
if maxg ~= 0,
gn = g/maxg;
else
gn = g;
end;
maxrf = max(abs(rf));
rfn = rf / maxrf;
% calculate pulse parameters
nrf = length(rf);
abswidth = sum(abs(rfn))/nrf;
effwidth = sum(abs(rfn).^2)/nrf;
area = sum(abs(rfn))/nrf;
pon = (rfn >= 0.00001);
temp_pw = 0;
max_pw = 0;
for n=1:nrf
temp_pw = temp_pw + pon(n);
if (and(pon(n) == 0, temp_pw ~= 0))
max_pw = max(max_pw, temp_pw);
temp_pw = 0;
end;
end;
max_pw = max_pw / n;
dty_cyc = sum(abs(rfn) > 0.2236)/nrf;
if dty_cyc < max_pw,
dty_cyc = max_pw;
end;
max_b1 = max(abs(rf));
int_b1_sqr = sum(abs(rf).^2 * SS_TS * 1e3);
rms_b1 = sqrt(sum(abs(rf).^2))/nrf;
thk_scale = thk * SS_GAMMA / SS_GAMMA_HYDROGEN * 10;
% Allow magnitude of RF to go negative, this will
% help reduce sensitivity to theta modulation since
% there is a possible delay on the system for this case
%
% Find pi jumps in phase and remove
% Do this by doubling phase and unwrapping 2*pi jumps
%
dang_rf = 2*angle(rfn);
dang_rf = dang_rf - dang_rf(1);
dang_rf = unwrap(dang_rf, 0.98*pi);
ang_rf = mod(dang_rf/2+pi,2*pi)-pi;
mag_rf = real(rfn .* exp(-i*ang_rf));
% if 1,
% figure;
% subplot(211)
% t = 1:length(rf);
% plot(abs(rf));
% hold on;
% plot(maxrf*mag_rf,'r--')
%
% subplot(212);
% plot(real(rf));
% hold on;
% plot(imag(rf), 'b--');
% plot(real(maxrf*mag_rf.*exp(i*ang_rf)), 'r:');
% plot(imag(maxrf*mag_rf.*exp(i*ang_rf)), 'r:');
% end;
switch (format)
case 'GE'
dat_name = sprintf('%s%03d.dat', root_fname, pulse_num);
fid = fopen(dat_name, 'w');
if fid == -1,
fprintf(1, 'Error opening %s \n', dat_name);
return;
end;
fprintf(fid,'%10d \t\t #Spectral-Spatial\n', 1);
fprintf(fid,'%10d \t\t #res\n', length(rf));
fprintf(fid,'%10d \t\t #pw\n',round(length(rf)*SS_TS*1e6));
fprintf(fid,'%10.7f \t\t #nom_flip \n',ang*180/pi);
fprintf(fid,'%10.7f \t\t #abswidth \n',abswidth);
fprintf(fid,'%10.7f \t\t #effwidth \n',effwidth);
fprintf(fid,'%10.7f \t\t #area \n',area);
fprintf(fid,'%10.7f \t\t #dtycyc \n',dty_cyc);
fprintf(fid,'%10.7f \t\t #maxpw \n',max_pw);
gamscale = SS_GAMMA/SS_GAMMA_HYDROGEN; % GE assumes max B1 is for application at 1H
fprintf(fid,'%10.7f \t\t #max_b1 \n',max_b1 * gamscale);
fprintf(fid,'%10.7f \t\t #max_int_b1_sqr \n',int_b1_sqr* gamscale^2);
fprintf(fid,'%10.7f \t\t #max_rms_b1 \n',rms_b1* gamscale^2);
fprintf(fid,'%10.3f \t\t #a_gzs \n',maxg);
fprintf(fid,'%10.3f \t\t #nom_thk(mm) \n',thk * gamscale * 10);
fprintf(fid,'%10d \t\t #isodelay\n',round(isodelay*1e6));
fprintf(fid,'%10d \t\t #g_pow \n',0);
fprintf(fid,'%10d \t\t #g_pos_pow \n',0);
fprintf(fid,'%10d \t\t #g_neg_pow \n',0);
fprintf(fid,'%10d \t\t #g_abs \n',0);
fprintf(fid,'%10d \t\t #g_dgdt \n',0);
fprintf(fid,'%10d \t\t #g_pwm \n',0);
fprintf(fid,'%10d \t\t #g_pwm_abs \n',0);
fprintf(fid,'# *************************************\n');
if (nargin == 7)
for b = 1:length(a_angs)
fprintf(fid,'# Band %d: [%.2f, %.2f] Hz, %.2f degree flip\n', ...
b, fspec(2*b-1), fspec(2*b), a_angs(b)*180/pi);
end
end
fclose(fid);
% Now write out RF and Gradient
%
rho_fname = sprintf('%s%03d.rho', root_fname, pulse_num);
signa(mag_rf,rho_fname,1);
theta_fname = sprintf('%s%03d.pha', root_fname, pulse_num);
signa(-ang_rf,theta_fname,1/pi);
g_fname = sprintf('%s%03d.grd', root_fname, pulse_num);
signa(gn,g_fname,1);
case 'Varian'
fid = fopen(sprintf('%s%03d.RF', root_fname, pulse_num),'wt');
fprintf(fid,'# %s\n', sprintf('%s%03d.RF', root_fname, pulse_num));
fprintf(fid,'# ***************************************************\n');
fprintf(fid,'# Spectral-spatial Matlab Package\n');
fprintf(fid,'# Nucleus = %s\n',SS_NUCLEUS);
fprintf(fid,'# Duration = %d us\n',round(length(rf)*SS_TS*1e6));
fprintf(fid,'# Isodelay = %d us\n',round(isodelay*1e6));
fprintf(fid,'# Resolution = %d us\n', SS_TS*1e6);
fprintf(fid,'# Flip = %.2f degrees\n',ang*180/pi);
fprintf(fid,'# Max B1 = %.4f Gauss\n',max_b1);
if (nargin == 7)
for b = 1:length(a_angs)
fprintf(fid,'# Band %d: [%.2f, %.2f] Hz, %.2f degree flip\n', ...
b, fspec(2*b-1), fspec(2*b), a_angs(b)*180/pi);
end
end
fprintf(fid,'# ***************************************************\n');
fprintf(fid,'# VERSION Matlab\n');
fprintf(fid,'# TYPE selective\n');
fprintf(fid,'# MODULATION amplitude\n');
fprintf(fid,'# EXCITEWIDTH -1.0000\n');
fprintf(fid,'# INVERTWIDTH -1.0000\n');
fprintf(fid,'# INTEGRAL %1.4f\n', sum(abs(rfn))/length(rfn));
fprintf(fid,'# RF_FRACTION -1.0000\n');
fprintf(fid,'# STEPS %d\n',length(rfn));
fprintf(fid,'# ***************************************************\n');
fprintf(fid,'%3.2f %4.2f 1.0\n',[-angle(rfn(:)).'*180/pi; 1023*abs(rfn(:)).']);
fclose(fid);
fid = fopen(sprintf('%s%03d.GRD', root_fname, pulse_num),'wt');
fprintf(fid,'# %s\n', sprintf('%s.GRD', root_fname));
fprintf(fid,'# ***************************************************\n');
fprintf(fid,'# Spectral-spatial Matlab Package\n');
fprintf(fid,'# Nucleus = %s\n',SS_NUCLEUS);
fprintf(fid,'# Duration = %d us\n',round(length(g)*SS_TS*1e6));
fprintf(fid,'# Resolution = %d us\n', SS_TS*1e6);
fprintf(fid,'# Points = %d\n',length(g));
fprintf(fid,'# Max Gradient Strength = %.4f Gauss/cm\n',maxg);
fprintf(fid,'# (Max Gradient Strength Constraint = %.2f Gauss/cm)\n',SS_MXG);
fprintf(fid,'# Max Slew Rate = %.2f Gauss/cm/ms\n',SS_MXS);
fprintf(fid,'# Slice thickness = %.1f mm\n',thk*10);
fprintf(fid,'# ***************************************************\n');
fprintf(fid,'%d 1\n',round(32767*gn));
fclose(fid);
end