[Insight-users] Problem in copying DICOM image: Study instance UID value is changed

[Mathieu Malaterre]

Subrahmanyam,

On Wed, Jul 2, 2008 at 11:30 AM, Subrahmanyam Gorthi
<subrahmanyam.gorthi at gmail.com> wrote:
> Dear Mathieu,
>
> Many THANKS for your detailed & prompt reply.
>
> Here is what I am actually trying to implement in ITK:
>
> Using a segmentation algorithm in ITK, I obtained the coordinates for 3-D
> ROI of a patient's image .
> I am now trying to export these results into a "DICOM-RT Structure-Set"
> file, for RT-Planning in IMRT.

*Very* cool ! Is this integrated with any of the Mesh and/or the Meta
Object in ITK too ?

> In addition to ROI module, as the DICOM-RT structure-set file has to contain
> other
> mandatory modules like patient-module, study module etc.,
> I am trying to selectively copy those modules from the associated patient's
> 3-D CT image.

Ah, I see why the UID can remains the same here. You did not modify the image :)

> I compared the tags of structure-set file that I am creating in ITK with
> the  file generated by another software that
> a Physician here is using in his hospital;
> he was manually drawing the contours on the CT image and the corresponding
> DICOM-RT structure-set file is generated by the software.

ok

> I observed that for the "structure-set" file generated by that software,
> "study-instance UID" tag is same as that of the
> other 3-D CT DICOM images and hence, I am trying to do the same for the file
> created through ITK.

Yup, in this very special case, then you are even encouraged to keep
the same UID :)

> From your reply, I understand the importance safety issues in  changing the
> default behavior.
> I would like to know:
> 1. Is it possible to change the default behavior for ONLY selected UIDs that
> are specified by the user?, and how?

I am not sure I understand that. but I guess you can do the in your
code (application level):

  if( currentuid match [set of known uids] )
    GDCMImageIO->KeepOriginalUIDOn ()

> 2. I want to finally contribute this code to ITK.

Even better !

> It would be very happy to know and most probably, implement any better ways
> or modifications to the current approach.
> Your suggestions in this regard will be of great help to me.

IMHO ITK is clearly lacking support for RTSTRUCT object, so any kind
of contribution would be AFAIK very welcome. For instance in a newer
release of GDCM, we have now integrated RTSTRUCT object nicely in VTK:

See:
  http://gdcm.sourceforge.net/html/classvtkGDCMPolyDataReader.html

Thus RTSTRUCT now appears as a set of vtkPolyData which is the base
object for 2D unstructred data in VTK.
I would think that a similar approach can (should?) be taken for ITK.
You would need to implement a itk::somethingIO that will read RTSTRUCT
and then convert it to either a itk::Mesh/itkQEMesh or SpatialObject
and convert back to file. This would be IMHO the most flexible for
people.

And thus you pipeline would become:

1. GDCMImageIO read (filename)
2. Segmentation
3. RTSTRUCT_IO write ouput_filename

does this make sense ?

Regards,
-- 
Mathieu