De-identification

De-identification of the datasets is mandatory before exchanging them between insititutions. We experienced serious issues when using the treatment planning system (TPS) to do this for 4D-PET-CT images of the dataset.

The breathing phase information of such 4D datasets is stored in proprietary DICOM tags. When importing these images into XiO or Focal (CMS Software, Elekta), these tags are stripped when saving the images in a proprietary format. Subsequent DICOM export of images (with altered patient demographics) does not restore these tags, obviously. This means that no breathing phase is available anymore for future analysis.

Furthermore, regular PET or MR datasets cannot be exported by the TPS. We therefore used a DCMTK tool (dcmodify) directly on the dataset. A simple Bash shell script to do this can be downloaded here.