<div>Jaety,</div>
<div> </div>
<div>The CT 9800 is a really old GE scanner. I believe it existed before DICOM. Sounds like this is a client problem.</div>
<div> </div>
<div>Bill<br><br> </div>
<div><span class="gmail_quote">On 3/12/07, <b class="gmail_sendername">Jaety Edwards</b> <<a href="mailto:jaety@cs.berkeley.edu">jaety@cs.berkeley.edu</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Hello All,<br>I've been trying to debug a problem with ITK loading certain DICOM<br>images, and I've finally realized that the problem is in the header of
<br>the DICOM image itself. The header has the following fields<br><br>PixelRepresentation = 1<br>BitsAllocated = 16<br>BitsStored = 12<br>HighBit = 11<br><br>This should mean that the pixel are signed, and 12 bits long. However,
<br>in reality the pixels are unsigned. Since ITK/gdcm is (correctly<br>according to the header) treating these pixels as signed, the highest<br>values are getting flipped to be negative.<br><br>This is not a bug in a single file. I've seen it in a number of files
<br>I've received. What I'm trying to figure out is how I can reliably<br>catch this problem in DICOM files I'm sent.<br><br>The header tells me (DerivationDescription) that the image is 'From GE<br>CT 9800 by DICOMatic
1.5 rev-1d'. Online, I've seen some references<br>indicating that this signed/unsigned confusion is a known problem with<br>some dicom files (e.g. <a href="http://tinyurl.com/3afz55">http://tinyurl.com/3afz55</a>), but I haven't been
<br>able to get any details. Is it a known problem in all files coming<br>from a GE CT 9800? Is it probably a problem with the DICOMatic<br>software the client used to convert it?<br><br>Other headers that might be clues:
<br>PixelPaddingValue = -32768<br>RescaleIntercept = -1000<br><br>Any suggestions greatly appreciated.<br>Thanks,<br>Jaety<br>_______________________________________________<br>Insight-users mailing list<br><a href="mailto:Insight-users@itk.org">
Insight-users@itk.org</a><br><a href="http://www.itk.org/mailman/listinfo/insight-users">http://www.itk.org/mailman/listinfo/insight-users</a><br></blockquote></div><br>