<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" style="display:none"><!--P{margin-top:0;margin-bottom:0;} p
{margin-top:0;
margin-bottom:0}--></style>
</head>
<body dir="ltr" style="font-size:12pt;color:#000000;background-color:#FFFFFF;font-family:Calibri,Arial,Helvetica,sans-serif;">
<p>Hi Ashok,</p>
<p><br>
</p>
<p>This is usually normal to have leftover signal outside the object, but it seems that you have more than normal.</p>
<p><br>
</p>
<p>How many iterations did you run ?</p>
<p><br>
</p>
<p>From your image, it seems that you are using a geometry without cylindrical symmetry.</p>
<p>If so, it may be possible that some regions of your field-of-view are not "seen" from a number of different angles that is enough to fully resolve these regions.</p>
<p><br>
</p>
<p>Hope this helps.</p>
<p><br>
</p>
<p>Best</p>
<p>Simon</p>
<p><br>
</p>
<div dir="ltr" style="color: rgb(33, 33, 33);">
<hr tabindex="-1" style="display:inline-block; width:98%">
<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>De :</b> Castor-users <castor-users-bounces@lists.castor-project.org> de la part de Tiwari, Ashok <ashok-tiwari@uiowa.edu><br>
<b>Envoyé :</b> dimanche 26 juillet 2020 16:13<br>
<b>À :</b> castor-users@lists.castor-project.org<br>
<b>Objet :</b> [Castor-users] about counts outside the phantom volume on reconstructed image</font>
<div> </div>
</div>
<div>
<div style="font-family:Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
Dear CASToR users and developers,</div>
<div style="font-family:Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
I've simulated a uniform phantom in GATE and exported the GATE data to CASToR for image reconstruction. During reconstruction, I've chosen only the true events and ran a reconstruction, with and without attenuation correction. Then I visualize the image using
ImageJ (see attached), but I do not understand why counts are appearing outside the phantom volume. Could anyone help me understand why this is happening here? Has anyone seen this before? Is it due to noise and/or scattering outside the phantom?</div>
<div style="font-family:Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
Thank you for your help in advance.</div>
<div>
<div style="font-family:Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div id="Signature">
<div>
<div></div>
<div></div>
<div id="divtagdefaultwrapper" dir="ltr" style="">
<p dir="ltr" style="margin-top:0px; margin-bottom:0px; margin-top:0px; margin-bottom:0px; text-align:left">
<span style="font-size:12pt; color:rgb(0,0,0)">Regards,</span></p>
<p dir="ltr" style="margin-top:0px; margin-bottom:0px; margin-top:0px; margin-bottom:0px; text-align:left">
<span style="color:rgb(0,0,0); font-family:Consolas,Courier,monospace; font-size:12pt">Ashok</span></p>
<p dir="ltr" style="margin-top:0px; margin-bottom:0px; margin-top:0px; margin-bottom:0px; text-align:left">
<span style="color:rgb(0,0,0); font-family:Consolas,Courier,monospace; font-size:12pt"><br>
</span></p>
<p dir="ltr" style="margin-top:0px; margin-bottom:0px; margin-top:0px; margin-bottom:0px; text-align:left">
<span style="color:rgb(23,78,134); font-family:Consolas,Courier,monospace; font-size:12pt">---------------------</span><br>
<span style="color:rgb(23,78,134); font-family:Consolas,Courier,monospace; font-size:12pt">Ashok Tiwari</span><br>
<span style="color:rgb(23,78,134); font-family:Consolas,Courier,monospace; font-size:12pt">Ph.D. Candidate</span><br>
<span style="color:rgb(23,78,134); font-family:Consolas,Courier,monospace; font-size:12pt">Department of Radiology & Physics</span><br>
<span style="color:rgb(23,78,134); font-family:Consolas,Courier,monospace; font-size:12pt">University of Iowa Hospitals and Clinics</span><br>
<span style="color:rgb(23,78,134); font-family:Consolas,Courier,monospace; font-size:12pt">Office: P158, MRF</span><br>
<span style="color:rgb(23,78,134); font-family:Consolas,Courier,monospace; font-size:12pt">200 Hawkins Drive</span><br>
<span style="font-size:12pt; color:rgb(23,78,134); font-family:Consolas,Courier,monospace">Iowa City, </span><span style="font-size:12pt; color:rgb(23,78,134); font-family:Consolas,Courier,monospace">IA </span><span style="font-size:12pt; color:rgb(23,78,134); font-family:Consolas,Courier,monospace">52242</span><br>
<span style="color:rgb(23,78,134); font-family:Consolas,Courier,monospace; font-size:12pt">ashok-tiwari@uiowa.edu</span><br>
</p>
<span style="color:rgb(102,102,102)"></span><span style="font-size:12pt; font-family:Consolas,Courier,monospace; color:rgb(117,123,128)"></span><span style="color:rgb(102,102,102)"></span><span style="font-size:12pt; font-family:Consolas,Courier,monospace; color:rgb(117,123,128)"></span><span style="color:rgb(102,102,102)"></span><span style="font-size:12pt; font-family:Consolas,Courier,monospace; color:rgb(117,123,128)"></span><span style="color:rgb(102,102,102)"></span>
<p style="margin-top:0px; margin-bottom:0px; font-family:Calibri,Helvetica,sans-serif; font-size:12pt; margin-top:0px; margin-bottom:0px">
<span style="font-size:12pt; font-family:Consolas,Courier,monospace; color:rgb(117,123,128)"></span><font color="#757b80"></font></p>
<span style="color:rgb(102,102,102)"></span><span style="font-size:12pt; font-family:Consolas,Courier,monospace; color:rgb(117,123,128)"></span><span style="font-size:12pt; font-family:Cambria,Georgia,serif; color:rgb(117,123,128)"></span><span style="color:rgb(118,62,155)"></span>
<p style="margin-top:0px; margin-bottom:0px; color:rgb(0,0,0); font-family:Calibri,Helvetica,sans-serif; font-size:12pt; margin-top:0px; margin-bottom:0px">
<span style="color:rgb(117,123,128)"><br>
</span></p>
</div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>