DICOM Glossary

A comprehensive reference of DICOM terminology.

A

Abstract Syntax The specification of data elements and semantics for a particular DICOM service, typically identified by a SOP Class UID.

Accession Number A unique identifier assigned by the RIS to link imaging studies to orders. Critical for billing and workflow integration.

AE Title (Application Entity Title) A unique 16-character identifier for a DICOM application on a network. Case-sensitive and used for addressing and authentication.

Association A network connection between two DICOM applications (SCU and SCP) that enables the exchange of DICOM messages.

C

C-ECHO The DICOM verification service used to test connectivity between DICOM applications. Equivalent to a network “ping”.

C-FIND The DICOM query service used to search for studies, series, or instances based on matching criteria.

C-GET A retrieve service where images are sent directly back to the requesting application.

C-MOVE A retrieve service where images are sent to a third-party destination specified by the requester.

C-STORE The DICOM storage service used to send images from one system to another.

Conformance Statement A formal document describing what DICOM services and features a product supports.

D

DICOM Digital Imaging and Communications in Medicine - the international standard for medical images and related information.

DICOMweb RESTful web services for DICOM operations, including QIDO-RS (query), WADO-RS (retrieve), and STOW-RS (store).

DIMSE (DICOM Message Service Element) The protocol layer that defines DICOM operations like C-STORE, C-FIND, C-MOVE, etc.

F

FHIR Fast Healthcare Interoperability Resources - a modern healthcare data exchange standard that can integrate with DICOM.

G

GSPS (Grayscale Softcopy Presentation State) A DICOM object that stores how an image should be displayed, including window/level, annotations, and zoom settings.

I

IHE (Integrating the Healthcare Enterprise) An initiative that develops integration profiles using standards like DICOM and HL7.

IOD (Information Object Definition) A template that defines what information can be stored in a DICOM object, organized into modules.

Instance A single DICOM object (e.g., one image slice), uniquely identified by its SOP Instance UID.

M

Modality The type of imaging equipment used to create medical images (e.g., CT, MR, US, CR, DX).

Modality Worklist (MWL) A DICOM service that provides scheduled procedure information from the RIS to imaging devices.

MPPS (Modality Performed Procedure Step) A DICOM service for reporting what procedures were actually performed, enabling workflow tracking.

P

PACS (Picture Archiving and Communication System) A system for storing, retrieving, and distributing medical images using DICOM protocols.

PDU (Protocol Data Unit) The basic unit of data exchange in DICOM network communication.

Pixel Data The actual image data in a DICOM file, stored in tag (7FE0,0010).

Presentation Context A combination of Abstract Syntax (SOP Class) and Transfer Syntax that is negotiated during association establishment.

Q

QIDO-RS Query based on ID for DICOM Objects - RESTful Services. The DICOMweb equivalent of C-FIND.

R

RIS (Radiology Information System) A system for managing radiology workflow, including scheduling, reporting, and billing.

S

SCP (Service Class Provider) The server role in DICOM communication that responds to requests from an SCU.

SCU (Service Class User) The client role in DICOM communication that initiates requests to an SCP.

Series A collection of related DICOM instances (images) within a study, typically from a single acquisition.

SOP Class (Service-Object Pair Class) A combination of an IOD and DIMSE services that defines what you can do with a type of DICOM object.

SOP Instance UID A globally unique identifier for a single DICOM object.

STOW-RS STore Over the Web - RESTful Services. The DICOMweb equivalent of C-STORE.

Structured Report (SR) A DICOM object that encodes findings and measurements in a machine-readable format.

Study A collection of all images and related information from a single examination, identified by Study Instance UID.

Study Instance UID A unique identifier for a study, shared by all series and instances within that study.

T

Tag A unique identifier for a DICOM data element, consisting of a Group Number and Element Number (e.g., 0010,0010).

Transfer Syntax Rules for encoding DICOM data, including byte order (endianness), VR encoding (explicit/implicit), and compression.

Type 1/2/3 Attributes

• Type 1: Required and must have a value
• Type 2: Required but may be empty
• Type 3: Optional

U

UID (Unique Identifier) A globally unique string that identifies DICOM entities (studies, series, instances, SOP classes, etc.).

V

VOI LUT (Value of Interest Look-Up Table) Transformation applied to pixel values for display, typically defined by Window Center and Window Width.

VR (Value Representation) The data type of a DICOM attribute’s value (e.g., DA for Date, PN for Person Name, UI for UID).

W

WADO-RS Web Access to DICOM Objects - RESTful Services. The DICOMweb equivalent of C-GET/C-MOVE.

Window Center/Width Parameters that define the range of pixel values to display, controlling image brightness and contrast.

Worklist See Modality Worklist (MWL).

Common Abbreviations

This glossary provides a quick reference for the terminology used throughout this tutorial.