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Hi Daniel,<br>
<br>
Welcome to RTK. It's always a pleasure to have new people around.<br>
Your problem is a frequently encountered issue with SART: your
reconstruction volume is too small, and some of the object lies
outside of it. <br>
<br>
Another user recently had a similar issue, so I'll copy/paste what I
wrote for her : <br>
An intuitive way to understand this is the following: the algorithm
tries to "explain" the attenuation it sees on the projections. If
the data has been partially truncated, some rays have "extra
attenuation" that has to go somewhere in the reconstructed volume.
The center of the reconstructed volume is constrained by all the
other rays, so this "extra attenuation" is pushed to the borders (or
the corners). If, on the other hand, the reconstructed volume is
large enough, this "extra attenuation" can go where it belongs, and
does not cause hyper attenuation on the borders.<br>
<br>
I've run the same command as you with spacing 2, and it gives a nice
reconstruction result (except for the border artifacts on the bottom
of the phantom, caused by the exact same phenomenon, which you can
get rid of by increasing the reconstructed volume's size again). So
just make sure your object is fully contained in the reconstructed
volume, and it should work.<br>
<br>
Best regards,<br>
Cyril<br>
<br>
<br>
<div class="moz-cite-prefix">On 08/14/2014 11:46 AM, Schoenke,
Daniel wrote:<br>
</div>
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cite="mid:C585521A05A63B4B8299BC5FDFECA0C1028F9F2E1C@MBX02.ad.uni-heidelberg.de"
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<div>Hello,</div>
<div>I´ve just begun to work with RTK. </div>
<div>Question: Why do I get strange results for the SART reco
with the Elekta dataset?</div>
<div>My commands:</div>
<div> </div>
<div>rtkelektasynergygeometry --image_db
../../../elekta/elekta/IMAGE.DBF --frame_db
../../../elekta/elekta/FRAME.DBF --dicom_uid
1.3.46.423632.135428.1351013645.166 -o elektaGeometry</div>
<div> </div>
<div>rtksart -g elektaGeometry -p
../../../elekta/elekta/img_1.3.46.423632.135428.1351013645.166/
-r .*.his -o sart.elekta.mha --verbose --spacing 1 --dimension
128</div>
<div> </div>
<div>One slice of the result:</div>
<div> </div>
<div><img moz-do-not-send="true"
src="cid:7a88d6f7-52d2-4b5c-bd5f-534b77cd64c2"> </div>
<div> </div>
<div>With rtkfdk its working fine (like in the wiki).</div>
<div>Can you help me please?</div>
<div>Thanks.</div>
<div>Daniel</div>
<div> </div>
<div> </div>
</font>
<br>
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<br>
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</blockquote>
<br>
<pre class="moz-signature" cols="72">--
--
Cyril Mory, Post-doc
CREATIS
Leon Berard cancer treatment center
28 rue Laënnec
69373 Lyon cedex 08 FRANCE
Mobile: +33 6 69 46 73 79</pre>
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