[Gate-users] Ecat7 sinogram output. Cannot open it with a viewer

[COMTAT Claude]

Hi,



I'm not aware of a freely available software that would allow you to display easily ecat7 sinograms. Most of the time, such software can display ecat7 images, but not ecat7 sinograms.



You can try to visualize them as a flat format, using Vinci. The header offset is 2048 bytes (main header --- 512, directory --- 512, and subheader --- 1024) and the data are stored as Big Endian. For the fist segment of HR+ data, you have to specify (X : number of radial bins, Y : number of axial bins in segment 0, Z : number of azimuthal bins) :



[cid:image002.jpg at 01CCECD2.0BFB7D20]



By default, an azimuthal mashing is applied to real HR+ ecat7 data (from 288 to 144). If you use the "raw" sinogram output format, you keep your 288 views.



In the raw sinogram output format, you have a series of 2D sinograms (2D means radial and angular), one per pair of rings in coincidence (1024 for a 32 rings system).



In the ecat7 output format, the data are organized differently and compressed (azimuthal and polar mashing).



Hope this helps,



Claude



-----Message d'origine-----
De : gate-users-bounces at lists.opengatecollaboration.org [mailto:gate-users-bounces at lists.opengatecollaboration.org] De la part de J.Jones at surrey.ac.uk
Envoyé : jeudi 16 février 2012 17:13
À :
Objet : [Gate-users] FW: Ecat7 sinogram output. Cannot open it with a viewer





   Hi,

I am new to GATE and use Gate 6.1.98524.

I want to use the ecat7 module to produce ecat7 sinograms for processing by STIR.

But first I would like to inspect the GATE / ecat7sinograms with a file viewer.



I based my run on examples/examplePET/PET_Ecat_System.mac..

Gate produces a non-empty file yourSinogram.S but I can not view it.

With Amide 'unable to read file' is reported.

With ecatssum from Turku PET centre 'Missing Matrix/matrices' is reported.

With Vinci (Latest down loaded yesterday.) 'valid ecat7 file but wrong plugin'.



Main Question: Does anybody know of a viewer that should work?



Whilst trying to read what is going on I noticed that 'Gate to Sinogram' was reporting

288 azimuthal bins but a few lines later GateSinoToEcat was reporting just 144.

Changing mashing from 2 to 1 increased the output file size but viewers would still

not open the yourSinogram.S file.  Does anybody think that might be significant?



Further reading led to one section of comment that indicated that 2D sinograms were

being built but another suggested 4D sinograms. Does anybody know which is correct?



Thanks

John



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