Embed the Patient information in the dicom image using dcmtk

I think I get it, you want to do overlays right? I just don't understand why you are trying to alter the actual pixel data within the image instead of storing an external file and moving on. The solution I posted was for actually altering the pixeldata, since you have to re-sign the file using a valid DICOM UID if you make any edits at all to the original file. I don't know what your application is, so it's hard to understand your motive for doing this, but one possible reason is that you are digitizing a CR from film and want to insert patient data into the DCM file so that when the file is sent to a DICOM printer it will burn into the film, right? In this case, you will have a DCM UID issued from the digitizer (which usually allows you to edit the demographic data right at the capture, by the way) with whatever the tech typed in at capture time burned into the header. So, say the tech types in 'patient^one', and you want to modify that to show up as 'another^patient' when it prints (as the overlay). You would create a new DICOM file (from a UID base/root) and then add the pixeldata and header to match your needs, then you have a uniquely signed DICOM file. Again, this is all presuming you have to modify the file for some reason... have you looked into DICONDE yet (DICOM + Non Destructive Edits)? I think you may be driving a nail with a sledgehammer in a way. All demographic data from the header is applied as overlays, with the exception of US and CR/Film (there are other exceptions, but those mainly will show up in weird formats). In the DICOM standard, this is almost certainly covered in the 'hanging protocols' area, so if this explanation does not cover what you are looking for, you could look there as well.

Hope that helps.