[Insight-users] DICOM measures

[michiel mentink]

Hi Luis Pereira,

If I understand correctly, you want to know how big the dicom volume is in
mm.
I think Luis has answered that already.

However, I can give you a different answer, why don't you calculate

(number of pixels along an axis) * (pixel size in mm)
(slice thickness) * (number of slices) ?

Those dimensions you can find in your dicom tags.

Good luck,

Michael




On Wed, Dec 9, 2009 at 4:00 PM, l.a.pereira <l.a.pereira at uol.com.br> wrote:

>
>  Luis, sorry i'm sending message again, I had problem with first email
> format.
>
> Luis, thanks for reply.
>
> My problem is know how tags I need use to calculate original DICOM
> dimensions x,y,z to milimeters.
>
> I believe that if I get the total physical extend image I will solve my
> problem.
>
> My application read a DICOM series and create a Volume. After that, the
> user will work from slices x,y,z obtained from
>
> vtkImagePlaneWidget->GetResliceOutput(), so I need to establish a
> co-relation between vtkImagePlaneWidget->GetResliceOutput() and the
>
> original measures of DICOM Series in milimeters.
>
>
>
>
>
> Em 09/12/2009 13:27, Luis Ibanez < luis.ibanez at kitware.com > escreveu:
>
>
> 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
>  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  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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