ACR/NEMA Digital Image Interface Standard (An Illustrated Protocol Overview)

Abstract

The American College of Radiologists (ACR) and the National Electrical Manufacturers Association (NEMA) have sponsored a joint standards committee mandated to develop a universal interface standard for the transfer of radiology images among a variety of PACS imaging devices .

The resulting standard interface conforms to the IS0/0SI standard reference model for network protocol layering . The standard interface specifies the lower layers of the reference model (Physical, Data Link, Transport and Session) and implies a requirement of the Network Layer should a requirement for a network exist. The message content has been considered and a flexible message and image format specified.

The following Imaging Equipment modalities are supported by the standard interface. . .

• CT Computed Tomography

• NM Nuclear Medicine

• MR Magnetic Resonance

• DS Digital Subtraction

• US Ultrasound

• DR Digital Radiology

The following data types are standardized over the transmission interface media. . . .

• IMAGE DATA

• HEADER DATA

• TEXT

• GRAPHICS

• DIGITIZED VOICE

• RAW DATA

• REPORTS

• OTHERS

This paper consists of text supporting the illustrated protocol data flow. Each layer will be individually treated. Particular emphasis will be given to the Data Link layer (Frames) and the Transport layer (Packets). The discussion utilizes a finite state sequential machine model for the protocol layers.