[Rtk-users] SART with Elekta Dataset

[Cyril Mory]

Hi Daniel,

Please keep the discussion about RTK on the mailing list : this 
conversation might come in handy to someone else in the future.
Regarding the data acquisition, here is what you need :
- Raw pixel data and meta-data of the projection images (number of 
pixels per line and column, number of lines and columns, number of 
projections, bits per pixel, size of the pixels in mm)
- Geometry data (you can find some information on the RTK geometry on 
the wiki, http://wiki.openrtk.org/index.php/Main_Page#Geometry). It 
usually consists in a few (from 9 to 15) floats per projection

I worked with a Philips C-Arm during my PhD indeed. I was employed by 
Philips, so I had the tools to export the raw data and geometry 
information readily available.
Depending on how well-documented the data you have is, it may range from 
very easy to very difficult to extract this information (if you have to 
look for it manually in undocumented Dicom fields, for example, it may 
take time, while if all you need is a geometry converter, it's a matter 
of a few hours).

Can you be precise on what kind of data you are able to extract from the 
Zeego ?

Regards,
Cyril

On 08/15/2014 04:16 PM, Schoenke, Daniel wrote:
>
> Thanks!
>
> My goal is to use RTK for Reconstruction of Siemens Artis Zeego 
> projection data. You´ve worked with a Philips Scanner -- so as I 
> understood from your PhD thesis. If you have any advices regarding 
> writing code for the read-in of data this would be very helpful for me 
> (I´m a physicist and no real programmer...)
>
> Again thanks a lot and have a nice weekend!
>
> Daniel
>
> *Von:*Cyril Mory [mailto:cyril.mory at creatis.insa-lyon.fr]
> *Gesendet:* Donnerstag, 14. August 2014 14:58
> *An:* Schoenke, Daniel; rtk-users at openrtk.org
> *Betreff:* Re: [Rtk-users] SART with Elekta Dataset
>
> Hi Daniel,
>
> Welcome to RTK. It's always a pleasure to have new people around.
> Your problem is a frequently encountered issue with SART: your 
> reconstruction volume is too small, and some of the object lies 
> outside of it.
>
> Another user recently had a similar issue, so I'll copy/paste what I 
> wrote for her :
> 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.
>
> 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.
>
> Best regards,
> Cyril
>
> On 08/14/2014 11:46 AM, Schoenke, Daniel wrote:
>
>     Hello,
>
>     I´ve just begun to work with RTK.
>
>     Question: Why do I get strange results for the SART reco with the
>     Elekta dataset?
>
>     My commands:
>
>     rtkelektasynergygeometry --image_db
>     ../../../elekta/elekta/IMAGE.DBF --frame_db
>     ../../../elekta/elekta/FRAME.DBF --dicom_uid
>     1.3.46.423632.135428.1351013645.166 -o elektaGeometry
>
>     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
>
>     One slice of the result:
>
>     With rtkfdk its working fine (like in the wiki).
>
>     Can you help me please?
>
>     Thanks.
>
>     Daniel
>
>
>
>
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>
>
> -- 
> --
> 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

-- 
--
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

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