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<p>Hi,</p>
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<p>I am currently trying to get started with RTK by modifying the FirstReconstruction example. In fact, I tried to replace the given projections of a sphere by some projections I created myself with Geant4. However, the result is not really convincing and I
am not sure if I messed with the geometry or if I got something else wrong.</p>
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<p>I have 90 projections (128x128 pixels, 2 deg rotation each time); from source to detector it's 46cm and 30cm from source to the object (simple small cylinder) centre, which lies in the centre of rotation:</p>
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<p> unsigned int numberOfProjections = 90;</p>
<p> double firstAngle = 0.; </p>
<p> double angularArc = 178.; </p>
<p> unsigned int sid = 300.;</p>
<p> unsigned int sdd = 460.; </p>
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<p>To read in the file, I used the ITK ImageFileReader, which works well. <span style="font-size:12pt">I am handing in my projections stacked in .mha format because it seemed that the sphere projections were generated and handed to the FDK reconstruction algorithm in
a similar way </span><span style="font-size:12pt">(is that correct?)</span><span style="font-size:12pt">. My projection values are double type and are of a range between 0 (air) and 1.</span></p>
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<p>For the FDK reconstruction I am choosing for my constant image source:</p>
<p> sizeOutput.Fill(128); // output should be 3D image 128x128x128 pixels</p>
<p> origin.Fill(0.); // I'm not entirely sure about this parameter? If my object is placed in the isocenter, this should work, right?</p>
<p> spacing.Fill(0.2); // pixel length in each direction is 0.2mm</p>
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<p>For the reconstruction itself, I didn't really change the original code but instead of 'rei', I handed my projections as input and then wrote the result to an output file. </p>
<p>I don't get any error when I run the program but the FDK gives some strange result (I am adding one screenshot of the first projection and the first slice of the reconstructed volume to my mail). </p>
<p>Maybe someone is familiar with this problem or sees what I am doing wrong? Thank you very much in advance!</p>
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<p>Best regards,</p>
<p>Stefanie</p>
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