DICOM: Medical Imaging Data Standards

DICOM (Digital Imaging and Communications in Medicine) is the international standard for representing, storing, and exchanging medical images together with their associated data. It defines both a file format that binds pixel data to descriptive metadata and a set of network services for transferring images and managing imaging workflow between modalities, archives, and viewing systems.

Definition

DICOM is a standard that encapsulates medical image pixel data within a structured information object carrying standardised metadata — patient, study, series, and acquisition attributes — and defines network services for storing, querying, and retrieving these objects, so that imaging devices and systems from different manufacturers can interoperate.

Scope

This entry covers the DICOM data model (the information object and its attributes), the DICOM network services for storage, query, and retrieval, and the role of DICOM in picture archiving and communication systems and radiology workflow. It treats DICOM as an interoperability standard and a methodological topic; it does not give imaging-protocol, acquisition, or clinical-interpretation guidance.

Core questions

• How does DICOM bind image pixel data to descriptive metadata in a single object?
• What is the patient–study–series–image information hierarchy?
• Which network services move images between modalities, archives, and viewers?
• How does DICOM relate to PACS and to radiology information systems?

Key concepts

• Information Object Definition (IOD) and attributes
• Patient–study–series–image hierarchy
• Service-Object Pair (SOP) classes
• Unique Identifiers (UIDs)
• DICOM network services (C-STORE, C-FIND, C-MOVE)
• Modality worklist
• Picture Archiving and Communication Systems (PACS)

Mechanisms

A DICOM object combines the image pixel data with a set of standardised attributes describing the patient, the study, the series, and the acquisition, organised in a four-level information hierarchy and identified by globally unique identifiers. The behaviour applied to an object is defined by a Service-Object Pair class, which pairs an information object with a service such as storage. DICOM network services then move and manage these objects: storage transfers images to an archive, query and retrieve services locate and pull prior studies, and the modality worklist supplies acquisition devices with scheduled patient and study information. Together these elements let imaging modalities, picture archiving and communication systems, and viewing workstations from different vendors interoperate within radiology workflow.

Clinical relevance

DICOM underpins the storage and exchange of essentially all cross-sectional and digital medical imaging, enabling images to be archived, retrieved, and reviewed across systems and sites. This entry describes how DICOM structures and transports imaging data; it is reference material about the standard and is not guidance for acquiring, processing, or interpreting medical images.

Evidence & guidelines

DICOM is maintained as a continuously updated standard by the DICOM Standards Committee (under the National Electrical Manufacturers Association) and is the basis for imaging conformance and the Integrating the Healthcare Enterprise profiles. Mildenberger, Eichelberg, and Martin (2002) provide an authoritative introduction to the standard's structure and services, and Benson and Grieve's textbook situates imaging interoperability within the broader standards landscape.

History

DICOM grew out of the ACR-NEMA standards developed by the American College of Radiology and the National Electrical Manufacturers Association in the 1980s to connect imaging equipment from different manufacturers. The 1993 release introduced the DICOM name, the object-oriented information model, and network services, and the standard has since been maintained and extended continuously to cover new modalities and workflow needs, becoming the universal basis for digital imaging exchange.

Key figures

• Peter Mildenberger
• Marco Eichelberg
• Oleg Pianykh
• Steven Horii

Seminal works

• mildenberger-2002

Frequently asked questions

Does a DICOM file contain only the image?

No. A DICOM object binds the image pixel data together with standardised metadata — patient, study, series, and acquisition attributes — in a single structured object, which is part of what makes cross-vendor imaging exchange possible.

What is the difference between DICOM and a PACS?

DICOM is the standard for the image objects and the network services that move them; a picture archiving and communication system (PACS) is the system that stores, distributes, and displays images, using DICOM to interoperate with modalities and viewers.