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Hi,</div>
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I thought the same in regards to trying to rotating in the other direction. Unfortunately, that has a similar artifact but with the reconstruction flipped. </div>
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Interestingly the overlap happens in a similar place but the internal structures are flipped</div>
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<div><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">1. Thanks!</span><br>
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<div><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">2. I should have worded that better. My projection images will be preprocessed in a float format. I wanted to check if there were restrictions on these
float values. Can input image data have negative values or high values? Or are they expected to have values between 0 and 1? I ask because some of the tools I have used to do this preprocessing (outside of RTK) have given negative values or 'stretched' the
data from 0 to 255 before saving.</span></div>
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<div><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Ben</span></div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Simon Rit <simon.rit@creatis.insa-lyon.fr><br>
<b>Sent:</b> Tuesday, June 2, 2020 5:28 PM<br>
<b>To:</b> Benjamin W. Maloney <Benjamin.W.Maloney.TH@dartmouth.edu><br>
<b>Cc:</b> rtk-users@public.kitware.com <rtk-users@public.kitware.com><br>
<b>Subject:</b> Re: [Rtk-users] Reconstruction Artifact</font>
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<div>Hi,</div>
<div>Sometimes rotating in the wrong direction gives this kind of artefacts. It's quite possible that we don't use the same convention as other toolkits regarding this.</div>
<div>For other questions:</div>
<div>1. Yes, you can use pixel as the unit. Then the image spacing should be 1 obviously and indeed, sdd and sid should be in pixels.</div>
<div>2. I don't fully understand. If your data is the output of a count detector, then you either rely on RTK to guess the counts without object to compute the line integral, or your preprocess your projections to pass line integrals in a float format.</div>
<div>Simon<br>
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<div dir="ltr" class="x_gmail_attr">On Tue, Jun 2, 2020 at 4:51 PM Benjamin W. Maloney <<a href="mailto:Benjamin.W.Maloney.TH@dartmouth.edu">Benjamin.W.Maloney.TH@dartmouth.edu</a>> wrote:<br>
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Hi all,<br>
<br>
Not sure if this is the right group to post to but here's my question:<br>
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I have a code that pulls in my own projection images and uses the FDKConeBeamReconstructionFilter for reconstruction<br>
<br>
The reconstruction I am getting has an artifact where it looks like there are two overlapping objects rotated. <br>
I have used other reconstruction toolboxes (mainly TIGRE in MATLAB) with the similar geometry inputs and not had this issue. I suspect the difference is in the parts of the geometry that are set by default. My question is if anyone has seen this before and
what input I should look into?<br>
<br>
I have a few more questions I may or may not be related:<br>
1. I assume that since I set the origin etc of my images in pixel, sid and sdd should be in pixels as well? <br>
2. Are there restrictions related the scalar values of the projection data? My data will be in detector counts rather than linear attenuation coefficients, is that okay?<br>
I have attached an image to show this issue. It is supposed to be a rectangular mammography phantom. It is a slice in XZ plane<br>
<br>
Thanks for the help!<br>
Ben<br>
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