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<div class="moz-cite-prefix">Hi Reza,<br>
<br>
Thanks for your feedback. This is a good question, but with no
easy good answer!<br>
<br>
For an arbitrary PET scanner, I think your suggestion of using the
crystal width is not too far from the reality (considering no
depth-of-interaction measurement).<br>
<br>
About the images you sent, there clearly are artifacts with 1mm
FWHM which cannot be seen with 2mm FWHM. They can come from
several sources:<br>
- reconstruction of simulated data without proper normalization
correction factors (in that case, the use of a PSF may
artificially reduce such artifacts)<br>
- a strictly line projector with too small voxels (if you are
using Siddon for example; in this case try the Joseph projector
which makes use of interpolations, it can decrease such artifacts)<br>
- or a combination of the two.<br>
<br>
Cheers,<br>
Simon<br>
<br>
Le 28/04/2017 à 18:55, M.R Teimoori a écrit :<br>
</div>
<blockquote
cite="mid:CACEZ9i_yFUdv5rEGFt1jN4K1zVeE=qhOmR=NLvg7VykD18F4Zw@mail.gmail.com"
type="cite">
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<div dir="ltr">Hello CASToR Users,
<div><br>
</div>
<div>I've been using CASToR to reconstruct images of various
human PET scanners to compare their image quality. So far,
through working with CASToR, I learned that the quality of the
reconstructed images for any PET scanner significantly varies
when changing the image convolver's FWHM. </div>
<div><br>
For example, the attached file shows images of a Derenzo-like
phantom obtained from simulations of a brain-dedicated PET
scanner and reconstructed with CASToR using listmode EM
reconstruction. This arbitrary PET scanner had LSO detectors
with a crystal width of 2 x 2 mm^2 and a crystal depth of 20
mm. In (A), images were reconstructed using "-conv
gaussian,2,2,3::psf" and in (B), the same listmode data were
reconstructed using the same reconstruction parameters but
with convolution parameters of "-conv gaussian,1,1,3::psf". </div>
<div><br>
</div>
<div>How legitimate does this sound to say that "for a PET
scanner, the convolver's FWHM should be equal to the scanner's
crystal width"? In general, are there any recommendations as
to how image convolver's parameters should be chosen for any
arbitrary PET scanner?</div>
<div><br>
</div>
<div>Thank you for your responses,</div>
<div><br>
</div>
<div>Cheers,</div>
<div>Reza</div>
</div>
<br>
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