DICOM versus HL7 for modality interfacing

Digital modalities such as CT, MRI, Ultrasound and Computerized Radiography systems, generating softcopy images to be used by a Picture Archiving and Communication System (PACS), need to identify the images properly in order to retrieve and manage them. In many cases, a technologist re-enters patient demographic and study related information at the modality, even although it is usually already present somewhere in the hospital information system (IS). In order to achieve a higher level of efficiency and uniquely identify the created image objects, it is obvious that an interface between the IS and modality to exchange this information is highly desired. There are two options for a modality vendor to implement an IS interface, either using the Health Level (HL7) or Digital Imaging Communication in Medicine (DICOM) communication standard. This paper will explain characteristics of both protocols, and demonstrate that it is preferred to use DICOM versus HL7. In addition, it will show that DICOM is supported by most modality vendors, based on the result of a poll of their Modality Worklist versus HL7 support.