write dicom rt file

Dear

I woul like to anonymize an dicom rt file, but rather than remove the patient IDs I would like to change them to have a control number

For example if the info.PatientName is John i would like to change to Something_01 or Something_53

For dicom images the is no problem:

        info=dicominfo(fileDCM);
        info.PatientName.FamilyName=NewSurname;
        info.PatientName.GivenName=NewName;
        info.PatientID=NewID;
        img = dicomread(fileDCM);
        dicomwrite(img,fileDCM,info)

For rtstructs and rtplan I can do something similar

        info=dicominfo(fileDCM);
        info.PatientName.FamilyName=NewSurname;
        info.PatientName.GivenName=NewName;
        info.PatientID=NewID;
        dicomwrite([ ],fileDCM,info,'CreateMode', 'Copy')

But for rtdose the code for images does not work, matlab report an error:

Writing multiple frames to one file requires a 'CreateMode' value of 'copy' or an object type of 'Secondary Capture Image Storage'

I think that the problem is that now img is an 4-D matrix and dicomwrite expect a 2-D matrix, but I do not know.

Any sugestion?

Thanks in advanced!

[Rik]

Sometimes it is easier to try to separate the image data from the other dicom fields in binary, and then put them back together after processing (with fread etc). However, I have never worked with rtdose data, so I don't know how feasible that strategy is.