This is a Normalised Instance which represents the state of a procedure step, and is:

A Presentation Context may be considered as a negotiated “sub-channel” with a DICOM Association through which the Application Entities have agreed to exchange information.

Radiotherapy objects were DICOM’s first foray into non-image Composite Instances - i.

In the vast majority of Associations, the Association is initiated by the SCU with the SCP responding, but DICOM does allow Reverse Role Negotiation whereby the initiator can request to be regarded as the SCP.

Storage Commitment is a DICOM service which allows a creator of images or other Composite Instances to check that they have been stored safely by a server (the SCP) before deleting from its own cache.

DICOM Structured reports are DICOM SOP Instances, organised just the same way as images etc., but which hold reports rather than images. They are typically therefore only a few kilobytes in size. They contain all the same indexing information as images, and therefore fit into the standard 4 level DICOM Hierarchy, complete with their own “psuedo-modality” of SR.