A short introduction to DICOM

What is DICOM?

DICOM (Digital Imaging and Communications in Medicine) is an open standard for the exchange of information in medicine e.g. digital images, additional information such as segmentation, surface definitions, image registrations, patient and workflow related information as well as different kinds of results or treatment information.

History of DICOM

It was created in 1985 by the ACR (American College of Radiology) and NEMA (National Electrical Manufacturers Association) in order to standardize the data transmitted between the different radiological equipment. The first two versions of the standard were respectively called "ACR/NEMA 300" and "ACR/NEMA 2.0". In 1993, with version 3.0, it was renamed from "ACR/NEMA" in DICOM. Since then new revisions of the standard appear at regular intervals, but the designation "3.0" is not used. Instead, the different versions of the standard are referred to by the year of publication of the respective version.

The advantages of DICOM

Before the widespread use of DICOM, each manufacturer of imaging equipment was using a proprietary data format, resulting in major problems for the management and maintenance in healthcare facilities (incompatibilities, cost, loss of information). Printouts of images was no longer essential and greatly reduced the cost of an X-ray.

Medical monitoring of patients, especially in case of serious diceases often requiring the transfer from a health facility to another depending on the resources and skills available, has directly benefited from the introduction of this standard. The images in DICOM format accompanying medical records are readable on any compatible hardware, and make the transport snapshots by traditional media obsolete.

Almost all manufacturers of imaging modalities (e.g. digital radiography, magnetic resonance, computed tomography or ultrasound), image processing systems and digital image archiving systems (e.g. PACS, Picture Archiving and Communication System) implement the DICOM standard into their products. This made the interoperability between systems from different manufacturers in a clinical environment possible.

What does the standard define ?

DICOM standardizes both the format for storing the data, as well as the communication protocol for the exchange.

It defines not only data fields (eg. information about images, reports, patients, studies, series), the syntax and semantics of commands and messages but also defines standard rules for the description of DICOM-compliant devices and software, as for each DICOM-compliant device a precise description of the system DICOM capabilities must be available and published (DICOM Conformance Statement).

Standardization process 

The DICOM standard is continuously being expanded by several working groups to meet the continuing development of medical, hardware and software technology. The working groups extend DICOM to several areas (e.g. radiotherapy, ECG, nuclear medicine, data security, ...). Members of the working groups are employees of medical device manufacturers, hospitals, universities and other research institutions.

Further developments will be added to the standard by so-called supplement. These are first written by one or several working groups and then submitted to the Working Group 6 (Base Standard) for evaluation. The supplement will be allocated a number if the extension appears useful. Once the working groups have finalized their supplements, they are the submitted to a vote by the DICOM Voting Members. After a positive vote, the supplement becomes valid and is incorporated into the next version of the DICOM standard.

Changes to the default or error in the documents can be submitted to the various working groups through a change proposal and will also be presented by the DICOM Working Group 6 (Base Standard) to the voting members.