[vtkusers] Matching CT and RT dose coordinates

[Bill Lorensen]

Maybe I missed something.

Why can't you use the same GDCM reader for both sets of images?


On Thu, Feb 24, 2011 at 9:50 AM, Jothy <jothybasu at gmail.com> wrote:
> FrameOfReferenceUIDs do match. I think the problem is with the different
> readers used to read CT and RT dose.
>
> I will use ImagePositionPatient to register the coordinates.
>
> Thank you
>
> Jothy
>
> On Wed, Feb 23, 2011 at 6:04 PM, Scott Johnson <Scott.Johnson at neuwave.com>
> wrote:
>>
>> If the FrameOfReferenceUIDs of the CT and the RT dose are the same, they
>> both exist in the same coordinate system, if they don’t, you will have to
>> register the dose to the CT somehow.
>>
>>
>>
>> Because the resolution of the dose will generally be different than the CT
>> a reasonable strategy is to loop through your CT voxels and use the position
>> at the center of that voxel to sample into the RT Dose grid.  When you
>> sample into the RT Dose you may need to interpolate the actual dose value.
>> That dose value determines your shading.
>>
>>
>>
>> The other issue to be aware of is that the dose grid may not completely
>> cover the CT image data.  This is probably why the origins are different for
>> your data.
>>
>>
>>
>>                                 -- Scott
>>
>>
>>
>> From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf
>> Of Jothy
>>
>> Sent: Wednesday, February 23, 2011 11:38 AM
>> To: gdcm-developers; VTK Mailing List; itk;
>> python-medphys at googlegroups.com
>> Subject: [vtkusers] Matching CT and RT dose coordinates
>>
>>
>>
>> Hi all,
>>
>> I am trying to overlay an dose shade on a CT slice.I am using
>> vtkDICOMImageReader to read the CT and vtkGDCMImageReader to display the
>> dose shade.But I am having problem with the coordinates.How to relate the
>> coordinates? For e.g: I  get ImagePositionPatient of CT image for central
>> slice as [-275,-524,-128.25] and ImagePositionPatient for dose as
>> [-228.65,-419.25,-122.5] adn their spacings are [1.074,1.074,3] and
>> [2.52.5.2.5] respectively for CT and Rt dose.
>>
>> The image looks as in the attached figure.
>>
>> Any hint
>>
>> Thanks
>>
>> Jothy
>
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