Radon Transformation - Digital Signal Processing for Medical Imaging Using Matlab - page 25

*fanbeamprojection{k};
%Fourier transformation of the modified fan beam projection
after zero padding
fanbeamprojection_modified2{k}=fft(fanbeamprojection_
modified1{k},1117);
%Multiplication with the fourier tansformation
of the weighted ramp
%filter after zero padding
%Computation of inverese fourier transformation
fanbeamprojection_modified3{k}=ifft(fanbeamprojection_
modified2{k}.*MODFILTER);
%Backprojection in the fanbeam structure
l=1;
for range=(-2*maxiangle):(4*maxiangle)/1116:(2*maxiangle)
X=-255:1:255;
Y=round((D-X)*tan(range));
Y1=-1*(Y+256)+512;
X1=-1*(X+256)+512;
for u=1:1:511
if((X1(u)<=511)&(Y1(u)<=511)&(Y1(u)>0))
RECONSTRUCTEDMATRIX(X1(u),Y1(u))=fanbeamprojection_
modified3{k}(l);
end
end
l=l+1;
end
%Multiplication with the weight matrix
RECONSTRUCTEDMATRIX=RECONSTRUCTEDMATRIX.*L_MATRIX;
%Obtaining the reconstructed matrix for beta(k)
RECONSTRUCTEDMATRIX=imrotate(RECONSTRUCTEDMATRIX,
-beta(k),'crop');
imagesc(RECONSTRUCTEDMATRIX)
pause(0.5)
DATA=DATA+RECONSTRUCTEDMATRIX;
end
figure
colormap(gray(256))
imagesc(DATA)