Standards Update: Integrating systems outside the radiology department

Standards Update: Integrating systems outside the radiology department

Herman Oosterwijk, president, OTech Inc.

The first meeting of the new DICOM Working Group 20, a joint DICOM/HL7 committee that deals with issues in integrating images into information systems, occurred at the recent HL7 meeting in San Diego.

The impetus for this joint standards activity is twofold. It has become increasingly clear that when providing patient information to a physician, including an image can complement and enhance that information. Images are also helpful for physician reimbursement. Under the new HIPAA (Health Insurance Portability and Accountability Act) regulations in the U.S., attaching digital images to an electronic claim would facilitate and simplify information exchange between payers and providers, in accordance with HIPAA mandates.

IHE, the joint activity being sponsored by RSNA and HIMSS to demonstrate and achieve interoperability between imaging and information systems, is also driving the need to address integration issues. These issues include:

• Information models. An accurate information model not only specifies the information involved in the transaction but explicitly defines the behavior and/or intention of the sender and receiver. Information models also define relationships. Both HL7 and DICOM have model definitions; alignment of both models is critical for interoperability.
• Attributes. HL7 and DICOM need to accommodate one another’s attributes so that information can be correctly aligned and communicated through the interface. For example, HL7 has certain identifiers that help to manage orders and their results. Imaging systems should accommodate these attributes and maintain them as part of their schedule list, or even store them in the image header.
• Length. DICOM is more exact in length specification than HL7. Some data elements in HL7 have an overall length limit while DICOM has a maximum length specification for the specific items that make up that data element. Again, ensuring that these elements align on both sides is necessary for true data compatibility.
• Functionality. There are some instances where either an HL7 or a DICOM interface can be used. For example, the normalized patient/study management services in DICOM exchange patient demographic information, something that can also be done with HL7 transactions. The challenge is to determine which service best fits the specific application.
• Encoding. HL7 is strictly character-based. However, DICOM has a powerful definition of data types for the encoding of image pixels and other binary data, in addition to the character-based information, such as patient demographics. It will take some work to accommodate these DICOM objects within the HL7 object framework, especially the new HL7 patient record architecture proposals.

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