[Insight-users] Dicom and Image Spacing

[Bill Lorensen]

Our handing of Image Position Patient in ITK is tricky to use. How are
you writing your DICOM volume? SeriesWriter or ImageWriter?

Bill

On Fri, Dec 7, 2012 at 9:02 AM, Alexander Schmidt-Richberg
<schmidt-richberg at imi.uni-luebeck.de> wrote:
> Thanks, Bill and Rômulo, for pointing that out. I just checked the
> current git version and the problem still remains: If I read, for
> example, a .mhd volume image with a spacing not equal to one (not a
> DICOM series), write it as DICOM volume file and then read the file, it
> will get a z-spacing of 1 (the in-plane spacing, however, is
> maintained). If this is really intended, it is kind of an awkward
> behavior, imo.
>
> Best regards
> Alex
>
> On Thu, 2012-12-06 at 15:52 +0000, Bill Lorensen wrote:
>> In ITK 3 and 4 we compute the distance between slice centers (spacing)
>> form the image position patient and orientation.
>> In ITKv4 there was a bug that was recently fixed. It will appear in
>> the 4.3 release. For now, you can try the latest 4.3 release candidate
>> which was announced recently on the mailing list.
>>
>> On Thu, Dec 6, 2012 at 4:35 AM, Rômulo Pinho
>> <romulo.pinho at lyon.unicancer.fr> wrote:
>> > Hello, Alex
>> > It is indeed a change in GDCM 2.x. You can read about it at
>> >
>> >
>>
> http://sourceforge.net/apps/mediawiki/gdcm/index.php?title=Using_GDCM_API#Automatic_ordering_of_slices_for_vtkGDCMImageReader.SetFileNames
>> >
>> >
>>
> http://sourceforge.net/apps/mediawiki/gdcm/index.php?title=Imager_Pixel_Spacing#Spacing_along_Z_.28third_dimension.29
>> >
>> >
>>
> http://sourceforge.net/apps/mediawiki/gdcm/index.php?title=Using_GDCM_API#Where_is_the_value_of_gdcm.Image.Spacing_coming_from_.3F
>> >
>> > Kind regards,
>> > Rômulo
>> >
>> >
>> >
>> > On 12/06/2012 10:16 AM, Alexander Schmidt-Richberg wrote:
>> >
>> > Hi,
>> >
>> > sorry if this has been discussed before. I'm sure I'm not the first
> to
>> > realize, but I couldn't find anything in the mailing lists.
>> >
>> > I have a problem with reading/writing volume images as Dicom files
>> with
>> > ITKv4, presumably due to the change from GDCM 1.x to 2.x.
>> >
>> > In ITK 3, the image spacing was stored in the tags
>> > "SpacingBetweenSlices" and "ImagerPixelSpacing". In v4,
>> > "NominalScannedPixelSpacing" is used for the in-plane spacing,
>> however,
>> > the z-spacing is not stored at all (if I'm right). That means, all
> of
>> > the "old" images I'm reading with ITK4 have a uniform spacing of 1,
>> > since the old tags are not interpreted. Moreover, programs like
>> MeVisLab
>> > ignore the new tag.
>> >
>> > Has this behavior been discussed? Is it working as intended and is
>> there
>> > any workaround?
>> >
>> > Best regards Alex
>> >
>> >
>> >
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>
>
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