Thanks for clarification,<br><br>But there are only two values x/y in header file of those low-dose CT data on tag Pixel Spacing (0028,0030).<br><br>In link, you sent me:<br><br>"Indeed the value for the spacing of the image could be coming from:
<ol><li> Imager Pixel Spacing (0018,1164)
</li><li> Nominal Scanned Pixel Spacing (0018,2010)
</li><li> Pixel Spacing (0028,0030)</li><li>Pixel Aspect Ratio (0028,0034)
</li></ol>1. and 2. and 4. are not present in those low-dose CT, so where does it take spacing for "z", when in Pixel Spacing tag, there are only two values, which ITK read as spacing in x,y?<br><br>Does it mean, that spacing in "z" for those low-dose CT data readed by ITK is correct?<br>
<br>I am just asking, because I don't know, where did it take that value spacing[2] = 4.41962, when there is nothing like that in DICOM header of those data. <br><br>Firstly I assumed that pixel spacing in "z" is the same as Slice Thickness, because in other data set from other imaging system is Slice Thickness equal to spacing in "z" when readed by ITK. <br>
<br>Maybe it's just coincidence, when you say, that those two are completely different aspects.<br><br><br><div class="gmail_quote">2011/4/13 Mathieu Malaterre <span dir="ltr"><<a href="mailto:mathieu.malaterre@gmail.com">mathieu.malaterre@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">FYI have a look at:<br>
<br>
<a href="https://sourceforge.net/apps/mediawiki/gdcm/index.php?title=Using_GDCM_API#Where_is_the_value_of_gdcm.Image.Spacing_coming_from_.3F" target="_blank">https://sourceforge.net/apps/mediawiki/gdcm/index.php?title=Using_GDCM_API#Where_is_the_value_of_gdcm.Image.Spacing_coming_from_.3F</a><br>
<br>
Slice Thickness does not means physical spacing, where did you read<br>
that ? It means the tickness of slice during acquisition time. I know<br>
some broken DICOM implementation uses it but this is is incorrect.<br>
<div><div></div><div class="h5"><br>
On Wed, Apr 13, 2011 at 2:50 PM, Bc. Michal Srna <<a href="mailto:michal@srna.info">michal@srna.info</a>> wrote:<br>
> Hello GDCM/ITK developers,<br>
><br>
> I just discovered, that ITKv4 (also ITK 3.20) reads probably wrong value of<br>
> DICOM tag "0018,050 Slice Thickness" from low-dose CT data provided by<br>
> SPECT/low-doseCT multimodal imaging system (manufacturer GE, model INFINIA)<br>
> .<br>
><br>
> If I am not wrong - when reading CT data ITK takes as value of spacing in<br>
> "z" axis value from tag "0018,050 Slice Thickness". In my original low-dose<br>
> CT data it is set to 6.1, but ITK reads spacing in "z" as 4.41962 and when I<br>
> save those data via ITK, it writes that incorrect value into that tag<br>
> "0018,050 Slice Thickness" and also into tag "0018,088 Spacing between<br>
> Slices".<br>
><br>
> So I am asking, if it's not bug, where does ITK take that value 4.41962,<br>
> when "0018,050 Slice Thickness" in original data is 6.1?<br>
><br>
> If it could help developers, I can provide example of those data, which are<br>
> affected by this problem.<br>
><br>
> Thanks for help!<br>
><br>
> --<br>
> S pozdravem Bc. Michal Srna<br>
><br>
> Fotografické portfolio:<br>
> <a href="http://michalsrna.cz" target="_blank">http://michalsrna.cz</a><br>
><br>
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--<br>
<font color="#888888">Mathieu<br>
</font></blockquote></div><br><br clear="all"><br>-- <br>S pozdravem Bc. Michal Srna<br><br>Fotografické portfolio:<br><a href="http://michalsrna.cz">http://michalsrna.cz</a><br>