The OSI Basic Reference Model is used to model the interconnection of medical imaging equipment. As shown in Figure 6.1-1 seven layers of communication protocols are distinguished. DICOM uses the OSI Upper Layer Service to separate the exchange of DICOM Messages at the Application Layer from the communication support provided by the lower layers.
This OSI Upper Layer Service boundary allows peer Application Entities to establish Associations, transfer Messages and terminate Associations. For this boundary, DICOM has adopted the OSI Standards (Presentation Service augmented by the Association Control Service Element). It is a simple service that isolates the DICOM Application Layer from the specific stack of protocols used in the communication support layers.
The DICOM Upper Layer protocol augments TCP/IP. It combines the OSI upper layer protocols into a simple-to-implement single protocol while providing the same services and functions offered by the OSI stack
The DICOM Upper Layer Service is defined in PS 3.8.
Figure 6.1-1DICOM Network Protocol Architecture