<div dir="ltr"><div>Hi,<br>This is a difficult question and I don't know the answer. I think what you observe is the famous edge artifact of SART reconstructions. My feeling is that that one can not trust values outside the FOV in any algorithm. I would mask the FOV if I were you, whatever the algorithm. On real data, I know it costs a bit of time but only a test with each initialization will give you an answer.<br>
</div><div>BTW, do you know any publication on ROI reconstruction+TV ?<br></div><div>Simon<br></div><div><br></div>PS : I'm investigating the maling list issue, I'll let you know when I get an answer.<br><div class="gmail_extra">
<br><br><div class="gmail_quote">On Wed, Apr 10, 2013 at 12:59 PM, MORY, CYRIL <span dir="ltr"><<a href="mailto:Cyril.Mory@philips.com" target="_blank">Cyril.Mory@philips.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div link="blue" vlink="purple" lang="FR">
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<p class="MsoNormal"><span style="color:#1f497d">Hi Simon, Hi Marc,</span></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="color:#1f497d" lang="EN-US">I’ve tried to send this mail to the mailing list, but it contains images, so a manual approval from the list’s manager is required.
</span></p>
<p class="MsoNormal"><span style="color:#1f497d" lang="EN-US">And last time I talked with Simon, he couldn’t find the interface to approve or reject the emails. So I forward it.</span></p>
<p class="MsoNormal"><span style="color:#1f497d"><br>
Regards,</span></p>
<p class="MsoNormal"><span style="color:#1f497d">Cyril </span></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span></p>
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<div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">De :</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> MORY, CYRIL
<br>
<b>Envoyé :</b> mercredi 10 avril 2013 11:54<br>
<b>À :</b> <a href="mailto:rtk-users@openrtk.org" target="_blank">rtk-users@openrtk.org</a><br>
<b>Objet :</b> SART vs FDK</span></p>
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<p class="MsoNormal"> </p>
<p class="MsoNormal">Hi,</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I’m wondering wheth<span lang="EN-US">er the reconstruction results I get with SART and FDK are normal or not. I’ve performed reconstructions of a moving Shepp and Logan phantom, using 308 projections equidistributed on a 360° circular
trajectory. The phantom is fully contained in the FOV. I’ve used the default projection and back projection operators for both SART (30 iterations of SART instead of the default 5) and FDK. And there are very noticeable differences outside the FOV, especially
at the edges of the projection cone, where SART produces high errors while FDK doesn’t.
</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">Is this a normal behavior ? I’m using these reconstructions to initialize an iterative algorithm, and my real data is truncated, so I’d prefer to use SART than FDK. These high errors outside the FOV make me hesitate,
though. </span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">SART :</span></p>
<p class="MsoNormal"><img src="cid:image002.jpg@01CE35E2.1DE522C0" height="743" width="1190"><span lang="EN-US"></span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">FDK : </span></p>
<p class="MsoNormal"><img src="cid:image004.jpg@01CE35E2.1DE522C0" height="749" width="1192"><span lang="EN-US"></span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">Regards,</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">==========================================</span></p>
<p class="MsoNormal"><span lang="EN-US">Cyril Mory</span></p>
<p class="MsoNormal"><span lang="EN-US">PhD student at Philips Medisys and CREATIS</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal">Groupement Hospitalier Est</p>
<p class="MsoNormal">Hôpital Cardiologique Louis Pradel</p>
<p class="MsoNormal">Laboratoire CREATIS - Bât. B13</p>
<p class="MsoNormal">CNRS UMR5220, INSERM U1044, INSA-Lyon, Univ. Lyon 1</p>
<p class="MsoNormal">28, Avenue du Doyen LEPINE</p>
<p class="MsoNormal">69677 Bron cedex FRANCE</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span lang="EN-US">Office : <a href="tel:%2B33%204%2072%2035%2074%2012" value="+33472357412" target="_blank">+33 4 72 35 74 12</a></span></p>
<p class="MsoNormal"><span lang="EN-US">Cell : <a href="tel:%2B33%206%2069%2046%2073%2079" value="+33669467379" target="_blank">+33 6 69 46 73 79</a></span></p>
<p class="MsoNormal"> </p>
</div>
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