[Insight-users] Bugs (maybe) in itkDicomImageIO.cxx and questions

[Mark Foskey]

There are definitely problems with this file.  I am in the process of 
adding the key you mentioned as a step towards reading a directory full 
of slices into a single 3D image.  A am also cleaning up some 
infelicities in the code, including the unfreed memory.

Streams are automatically closed by their destructors, when they go out 
of scope.

This has been on my plate for some time.  Thanks for handing me a fork.

Feng Ma wrote:
> Hi,
> 
>  I worked a little bit with file itkDicomImageIO.cxx to read CT dicom 
> files. I found a few place that are possibly bugs.
> 
>  1. In method CanReadFile(), inputStream is not closed. Nor is it closed 
> in CheckTagTable(). I am not experienced in C++. Does an open stream 
> need not to be closed?
> 
>  2. In method ReadImageInformation(), array value, spac1value, 
> spac2value are not freed in the end of this method. inFile stream is not 
> closed.
> 
> 
>  Below are my questions.
> 
>  1. Dicom header size. I printed out m_InputPosition, which is supposed 
> to be the dicom header size. I read one image and got the header size 
> 2522 (which is a 512x512 2 bytes CT image, file size 526812). this 
> number is different from what I got from commecial merge library. The 
> mergelib number is 2524 which is closer to the guess 
> 526812-512x512x2=2524. This happens in many files. Is the header size 
> reported by itkDicomImageIO class possibly wrong?
> 
>  2. Unable to read image position tag (0x0020 0x0032). This tag is very 
> important to determine the z-value of the dicom image in a volume. When 
> I add a segment of code to read this tag, method GoToTag() simply can 
> not find it. I posted my code segment here. The last few lines in the 
> posted method CheckTagTable() is what I added. I did rewind the file 
> pointer before call GoToTag(). What's could be wrong?
> 
> Btw, my ITK version is Oct 7 CVS version.
> 
> Thank you very much.
> 
> -Feng
> 
> **** Run output ****
> fma@ctreg1:/r2net/space_fma1/vhds/test 728 % 
> ../../Devel/ITKDebug/bin/DicomImageViewer 
> /r2net/space_fma2/data/LV00000500/LV00000500_152.dcm
> Loading File: /r2net/space_fma2/data/LV00000500/LV00000500_152.dcm
> Can not locate position tag 0x0020 0x0032
> Header Size: 2522
> ...Done Loading File
> 
> **** Code segment of CheckTagTable() ****
> 
> bool DicomImageIO::CheckTagTable(std::ifstream & inputStream,std::list 
> <Tag> &TableOfTags) const
> {
>  long int i, j;
>  long int max;
>  Tag tagcurrent;
>  unsigned char c;
>  char chaine[4];
> 
>  i=0;
>  //0x7FE0 and 0x0010 is the last tag before data pixel
>  if(!DicomImageIO::GoToTheEndOfHeader(inputStream,i,tagcurrent))
>  {
>    return (false);
>  }
>  else
>  {
>    TableOfTags.push_back(tagcurrent);
>    max=i;
>    //start the reading of the Stream from the begining
>    inputStream.seekg(0);
>    i=0;
>  }
> 
>  ////0x0028 and 0x0010 >> tag before the number of rows
>  if(!DicomImageIO::GoToTag(inputStream,0x0028,0x0010,i,max,tagcurrent))
>  {
>    return false;
>  }
>  else
>  {
>    TableOfTags.push_back(tagcurrent);
>  }
> 
>  //0x0028 and 0x0011 >> tag before the number of columns
>  if(!DicomImageIO::GoToTag(inputStream,0x0028,0x0011,i,max,tagcurrent))
>  {
>    return false;
>  }
>  else
>  {
>    TableOfTags.push_back(tagcurrent);
>  }
> 
>  //0x0028 and 0x0030 >> tag before each the value of spacing
>  if(!DicomImageIO::GoToTag(inputStream,0x0028,0x0030,i,max,tagcurrent))
>  {
>    //if there is no information about the spacing, we set the value 
> compt to 0
>    tagcurrent.Balise1[1]=0x28;
>    tagcurrent.Balise1[0]=0x00;
>    tagcurrent.Balise2[1]=0x30;
>    tagcurrent.Balise2[0]=0x0;
>    tagcurrent.compt=0;  //
>    TableOfTags.push_back(tagcurrent);
>    //start the reading of the Stream from the begining
>    inputStream.seekg(0);
>    i=0;
>  }
>  else
>  {
>    TableOfTags.push_back(tagcurrent);
>  }
> 
>  //0x0028 and 0x0100 >> tag before the number of bits allocated
>  if(!DicomImageIO::GoToTag(inputStream,0x0028,0x0100,i,max,tagcurrent))
>  {
>    return false;
>  }
>  else
>  {
>    TableOfTags.push_back(tagcurrent);
>  }
> 
>  //0x0028 and 0x0103 >> tag before the place of sample representation
>  if(!DicomImageIO::GoToTag(inputStream,0x0028,0x0103,i,max,tagcurrent))
>  {
>    return false;
>  }
>  else
>  {
>    TableOfTags.push_back(tagcurrent);
>  }
> 
>  i = 0;
>  inputStream.seekg(0);
>  ////0x0020 and 0x0032 >> tag before value of position
>  if(DicomImageIO::GoToTag( inputStream,0x0020,0x0032,
>                             i,max,tagcurrent)){
>     std::cout << "Position tag located.\n";
>  }
>  else
>     std::cout << "Can not locate position tag 0x0020 0x0032\n";
> 
>  return(true);
> }
> 
> 
> 
> 
> 
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-- 
Mark Foskey    (919) 843-5436   Computer-Aided Diagnosis and Display Lab
mark_foskey@unc.edu             Department of Radiology, CB 7515, UNC
http://www.cs.unc.edu/~foskey   Chapel Hill, NC  27599-7515