De-identification (DICOM anonymisation)
De-identification is the removal or replacement of patient-identifying data elements in a DICOM object so that the images can no longer be linked to an individual through that metadata.
What De-identification (DICOM anonymisation) means in practice
The standard defines it as a set of confidentiality profiles, each naming exactly which attributes to remove, replace or keep, because "anonymise" on its own is too vague to implement consistently. Two points are routinely missed: identifiers also appear in private elements and in text burned into the pixels themselves, and removing too much can leave a study that no longer displays correctly — which is why the profiles specify per-attribute actions rather than blanket deletion.
Source
This definition follows NEMA PS3.15 Annex E — Attribute Confidentiality Profiles, published by NEMA as part of the DICOM standard.
Related terms
DICOM tag
A DICOM tag is the pair of numbers — a group number and an element number — that identifies one specific data element inside a DICOM file, such as (0010,0010) for Patient's Name.
Pixel Data
Pixel Data is the DICOM data element, tag (7FE0,0010), that holds the actual image content of an instance, encoded according to the file's transfer syntax.
Patient, Study, Series and Instance
DICOM organises imaging data in a four-level hierarchy: a Patient has Studies (one imaging visit each), a Study has Series (one acquisition run each), and a Series has Instances (the individual images or objects).