File Storage

MRRL

%% 1A Design of RF pulse for 1H (3.0T) with 5mm slice thickness at isocenter

for tbw = [4,16]

samples = 512;

rf = (pi/2)*wsinc(tbw,samples);

dz = 0.3; % slice thickness [cm]
gam = 4.257; % gyromagnetic ratio for 1H [kHz/G]

Gz = 8; % slice select gradient amplitude [G/cm]

df = Gz*gam*dz; % BW in kHz

pulseduration = tbw/df; % RF pulse duration [ms]

rfs = rfscaleg(rf, pulseduration); % Scaled to Gauss

dt = pulseduration/samples;
t = (1:length(rfs))*dt; % in msec

b1 = [rfs zeros(1,samples/2)]; % in Gauss
g = Gz*[ones(1,samples) -ones(1,samples/2)]; % in G/cm
t_all = (1:length(g))*dt; % in msec

figure;
subplot(311); plot(t_all,b1); grid on; title(['TBW: ' int2str(tbw)]);
xlabel('Time (msec)'); ylabel('B_1 (Gauss)');
subplot(312); plot(t_all,g); grid on;
xlabel('Time (msec)'); ylabel('G_z (Gauss/cm)');

x = (-4:.01:4); % in cm
f = 0; % center frequency in Hz
dt = pulseduration/samples/1e3;
t = (1:length(b1))*dt; % in sec

% Bloch Simulation
[mx,my,mz] = bloch(b1(:),g(:),t(:),1,.2,f(:),x(:),0);

% Transverse Magnetization
mxy = mx+1i*my;

subplot(313); plot(-x,abs(mxy));
grid on; xlabel('z position (cm)');

end

%% 1B Design of RF pulse for 1H (3.0T) with 3mm slice thickness at z=+10mm

tbw = 16;