[vtkusers] What ditermines whether the slice order should be reversed?

[David Gobbi]

Hi Liu Peng,

What versions of VTK and vtk-dicom you are using?

 - David

On Mon, Aug 28, 2017 at 12:31 AM, Liu_tj <tjlp at netease.com> wrote:

> Hi, David,
>
> As far as I know, in the RCS system, the direction of Z axis is from foot
> to head.So by default, the slice order in your dicom reader is consistent
> with the RCS system.When the reader sorts the slices, does it consider the
> Patient Postion tag(0080,5100)? Some doctors might use some DICOM tools
> which the slice order is from head to foot and get used to that.
>
> My code block for load slices is as follow:
>
>        vtkStringArray* vtkDICOMFilePaths = vtkStringArray::New();
>         vtkDICOMFilePaths->SetNumberOfValues(aDICOMFilePaths->Length);
>         for(int i = 0; i < aDICOMFilePaths->Length; i ++)
>         {
>             String^ filePath = aDICOMFilePaths[i];
>             const char* filePathByChars = MDKStringUtility::
> NStringToChars(filePath);
>
>             vtkDICOMFilePaths->SetValue(i, filePathByChars);
>         }
>
>         vtkDICOMReader* reader = vtkDICOMReader::New();
>         vtkImageData* imageData = reader->GetOutput();
>
> Thanks
> Liu Peng
> 在2017-08-28，"David Gobbi" <david.gobbi at gmail.com> 写道：
>
> -----原始邮件-----
> *发件人:*"David Gobbi" <david.gobbi at gmail.com>
> *发送时间:*2017年08月28日 星期一
> *收件人:*"Liu_tj" <tjlp at netease.com>
> *抄送:*"vtkusers" <vtkusers at vtk.org>
> *主题:*Re: What ditermines whether the slice order should be reversed?
>
>
> Hi Liu Peng,
>
> The vtkDICOMReader sorts according to the Image Plane Module:
> http://dicom.nema.org/MEDICAL/dicom/current/output/chtml/
> part03/sect_C.7.6.2.html
> That is, the slices are sorted in a manner such that the VTK image data
> has a right-handed coordinate system (called an RCS in the link above).
>
> Sorting the slices to get an RCS means that sometimes the slices will be
> sorted the same as the InstanceNumber, and sometimes they will be sorted
> opposite to InstanceNumber, depending on the order in which scanner ordered
> the slices.
>
> You can perform the sorting yourself by calling reader->SortingOff().  If
> Sorting is Off, the reader will take the slices in the same order as the
> vtkStringArray that you passed to reader->SetFileNames().
>
> If you send me the block of code where you set up and call the reader,
> then I might be able to provide more help.  Don't forget to also say what
> versions of VTK and vtk-dicom you are using.
>
> Cheers,
>  - David
>
>
>
> On Sun, Aug 27, 2017 at 10:41 AM, Liu_tj <tjlp at netease.com> wrote:
>
>> Hi,
>>
>> I have a question about the DICOM slice order. I use the DICOM reader by
>> David Gobbi to read the slice series to vtkImageData. And I found that the
>> oder is the same as the order by DICOM instanceNumber tag. However, some
>> doctors tell me that the order should be reversed because the scan should
>> start from head to foot.
>>
>> @David, if I need to reverse, how to achieve that by your DICOM reader?
>>
>> Thanks
>> Liu Peng
>>
>>
>>
>>
>
>
>
>
>
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