<html><head></head><body><div style="font-family: Verdana;font-size: 12.0px;"><div>Hello,</div>
<div>I've got a questions regarding to the forward projectors for the S-ART reconstruction.</div>
<div>Let's say there are some xray projection images from an xray machine taken with a circular trjectory (cone beam)</div>
<div>The perspective view for these real projection images have been taken into account, of course.</div>
<div>The forward projector creates a virtual projection image of the volume to be reconstructed. When this forward projection</div>
<div>takes place does the forward projector also take into account the perspective view of the real CT system ?</div>
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<div>Let's say we have a simple raycast forward projector.</div>
<div>The geometry (focus, object, detector) are all given in real world units where the object's center is (0, 0, 0).</div>
<div>By "real world units" I mean the physical dimensions from the CT system. For instance, if the distance between</div>
<div>the object's center and the xray-source is 500mm, the the xray-source position is (0,0, -500.0).</div>
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<div>So the virtual projection image is created as follows:</div>
<div>1: setup ray from xray-source to the current detector pixel</div>
<div>2: determine entry point and exit point of this ray with the physical bounding volume</div>
<div>3: sample the volume along the ray, from entry point to exit point</div>
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<div>Does these steps per se include the perspective view ? Since the geomtry (position of focus object detector) for the reconstruction is modeled</div>
<div>to imitate the real CT system's geometry, it should ?</div>
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<div>best regards,</div>
<div>Robert</div>
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