The DICOM Standard
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## The DICOM Standard

This Standard, which is currently designated Digital Imaging and Communications in Medicine (DICOM), embodies a number of major enhancements to previous versions of the ACR-NEMA Standard:

- It is applicable to a networked environment. The ACR-NEMA Standard was applicable in a point-to-point environment only; for operation in a networked environment a Network Interface Unit (NIU) was required. DICOM supports operation in a networked environment using the industry standard networking protocol TCP/IP.

- It is applicable to an off-line media environment. The ACR-NEMA Standard did not specify a file format or choice of physical media or logical filesystem. DICOM supports operation in an off-line media environment using industry standard media such as CD-R and MOD and logical filesystems such as ISO 9660 and PC File System (FAT16).

- It specifies how devices claiming conformance to the Standard react to commands and data being exchanged. The ACR-NEMA Standard was confined to the transfer of data, but DICOM specifies, through the concept of Service Classes, the semantics of commands and associated data.

- It specifies levels of conformance. The ACR-NEMA Standard specified a minimum level of conformance. DICOM explicitly describes how an implementor must structure a Conformance Statement to select specific options.

- It is structured as a multi-part document. This facilitates evolution of the Standard in a rapidly evolving environment by simplifying the addition of new features. ISO directives that define how to structure multi-part documents have been followed in the construction of the DICOM Standard.

- It introduces explicit Information Objects not only for images and graphics but also for waveforms, reports, printing, etc.

- It specifies an established technique for uniquely identifying any Information Object. This facilitates unambiguous definitions of relationships between Information Objects as they are acted upon across the network.

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