[Insight-users] DICOM measures

[Luis Ibanez]

Hi Luis,

Could you please be more specific regarding
what you call "measures"   ?

Are you referring to the total physical extent of the image ?
(e.g. the volume of space that is occupied by the image).

or are you referring to measuring distances between pairs
of pixels in the image ?

If you are talking about the second case, then what
you want to do is to take the indices of  both pixels.
(let's call them index1 and index2) and do the following:


  const ImageType * image = reader->GetInput();
  ImageType::PointType point1;
  ImageType::PointType point2;

  image->TransformIndexToPhysicalPoint( index1, point1 );
  image->TransformIndexToPhysicalPoint( index2, point2 );

  const double distance = point1.EuclideanDistanceTo( point2 );

  That value of "distance" will be measured in millimeters,
   which is the default unit in DICOM,

  When the indices are converted to physical points, the
  computation process will take into account:

              A) The coordinates of the image Origin
              B) The values of pixel spacing
              C) The orientation (direction) of the image

   The resulting value of "distance" will therefore be
   in the units of physical space.


As Michiel pointed out, the values of (A), (B) and (C)
are defined in the DICOM tags.   If you are curious
about the values, you could also print them out with

    reader->Update();
    const ImageType * image = reader->GetInput();
    std::cout << image->GetOrigin() << std::endl;
    std::cout << image->GetSpacing() << std::endl;
    std::cout << image->GetDirection() << std::endl;


---

If you were talking about other type of "measures",
please, describe them in detail.


     Thanks,


           Luis


------------------------------------------------------------------------------------------
On Wed, Dec 9, 2009 at 8:13 AM, michiel mentink
<michael.mentink at st-hughs.ox.ac.uk> wrote:
> Hi Luis,
>
> try example Examples/IO/DicomSeriesReadPrintTags.cxx.
> It prints the most important tags.
>
> It is described in the itk software guide paragraph 7.12.6
> You can also see those tags summarized on my page on:
> https://sites.google.com/site/michielmentink/programming/itk/image-translate
> (on the bottom).
>
> greets,
>
> Michael
>
> On 12/9/09, l.a.pereira <l.a.pereira at uol.com.br> wrote:
>>
>> Hi,
>>
>> I'm reading a DICOM series with GDCMImageIO.
>>
>> Now, I need obtain the measures of this DICOM series to convert it in
>> milimeters.
>>
>> How can I do it ?
>>
>> There is some tags in DICOM header where I can calculate/convert this
>> measures to milimeters ?
>>
>> Thanks,
>>
>>
>>
>> Luis
>>
>>
>>
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