[Insight-users] Update: Problem while reading dicom series --> wrong positioning in the space

["Eliana M. Vásquez Osorio"]

Hello itk-users.
I have tricked the system by changing the sign for the spacing(2).
ImageType::SpacingType spacing = dcmreader->GetOutput()->GetSpacing();
spacing[2] = -spacing[2];
dcmreader->GetOutput()->SetSpacing( spacing );

and now the z-coordinate behaves as expected!.  Is this a bug? or is it 
there something special I should do before reading the dicom files?  I 
can send a print out of all the flags that are in the data... maybe it 
will give a hint on what's the problem

Eliana


-------- Original Message --------
Subject: 	Problem while reading dicom series --> wrong positioning in 
the space
Date: 	Tue, 29 Jan 2008 11:32:04 +0100
From: 	"Eliana M. Vásquez Osorio" <e.vasquezosorio at erasmusmc.nl>
To: 	insight-users at itk.org



Hello itk-users.
I came across a problem while reading dicom series. I got 100 slices of 
512x512 pixels.

Checking the image tags with a viewer, I can see that the dicom header 
'0020|1041': Slice Location vary between
1339.18 and 1636.12. And the '0020|0032': Image Position Patient vary 
between [0, 0, -1339.18] and [0, 0, -1636.12] .

When I read the image, using ImageSeriesReader + GDCMImageIO, the volume 
Z-coordinate vary between
-1339.18 and -1048.13.
I wonder is why the Z-coordinate changes the range from (-1636.12 and 
-1339.18) to (-1339.18 and -1048.13)...
... Any idea?

I checked the Image Orientation tag '0020|0037', and it is 1\0\0\0\-1\0. 
That will account for the minus in the Z, but not for the change in the 
range. I think it's something related to the scaling, when it is defined...


Regards,

-- 
Eliana M. Vásquez Osorio
PhD Student (OIO)
Erasmus Medical Center - Daniel den Hoed Cancer Center
Department of Radiation Oncology
Groene Hilledijk 301 
3075 EA Rotterdam
The Netherlands

T: +31 10 – 43 91 491 
F: +31 10 – 43 91 012
E-mail: e.vasquezosorio at erasmusmc.nl




-- 
Eliana M. Vásquez Osorio
PhD Student (OIO)
Erasmus Medical Center - Daniel den Hoed Cancer Center
Department of Radiation Oncology
Groene Hilledijk 301 
3075 EA Rotterdam
The Netherlands

T: +31 10 – 43 91 491 
F: +31 10 – 43 91 012
E-mail: e.vasquezosorio at erasmusmc.nl