DICOM PS3.3 2019a - Information Object Definitions

8.9 Equivalent Code Sequence

The Equivalent Code Sequence (0008,0121) Attribute may optionally be used to convey different codes for the same concept.

Equivalence is defined as having the same or similar meaning, and requires that equivalent concepts do not include different aspects, properties, features, characteristics, or parameters.


E.g., the SNOMED and FMA codes for a structure of the breast, (T-04000, SRT, "Breast") and (57983, FMA, "Breast") would be considered equivalent. Neither would be equivalent to concepts that pre-coordinated other aspects such as laterality, e.g., (T-04030, SRT, "Left breast"), or entire body organ, e.g., (T-04009, SRT, "Entire breast").

Some scenarios in which it is helpful for the creating system to send equivalent codes include:

The Table 8.8-1b may be used to identify a Context Group from which the codes were selected, such as for a particular cross-institutional, cross-application context for trials, research and knowledge-based applications.

DICOM PS3.3 2019a - Information Object Definitions