Image Object Change Management (IOCM) is a relatively new service in DICOM which uses (some would say, abuses) KOS object to provide a controlled mechanism for requesting the deletion of images from an archive. The process is as follows:
The SCU creates a KOS object which defines both the reason for deletion and the list of images to be deleted.
The KO object is itself part of the study (i.e. it shares a Study UID) with the images to be deleted.
The KOS is sent to the SCP, which is expected to act on the instuctions, and possibly (depending on the type of deletion) to either:
The first option is used where there is a safety aspect to the deletion (e.g. wrong patient), and the second option is used where the images have simply outlived their expected retention period (but might subsequently be restored from backup or a patient-provided CD etc.)