DICOM Update: DICOM reaches agreement with SNOMED

DICOM Update:
DICOM reaches agreement with SNOMED

By Herman Oosterwijk, president, OTech Inc.

The College of American Pathologists (CAP) has officially granted the DICOM committee the right to use about 1000 SNOMED terms, which are needed to encode information in DICOM objects.

Many insurance providers and HMOs accept billing information only when it includes CPT or similar codes. Procedure codes are typically passed to the image acquisition modalities using the DICOM-modality work list. This information is then copied and becomes part of the image header.

Instead of identifying something merely as a chest exam, a well-defined code specifies what the exam consists of, such as 2-view or 3-view. Another group of codes is used in DICOM images to identify such anatomic references as the body part examined, measurement information, and examination context information. Using these codes instead of free text is critical if the receiver is to know where and when to route the images and how to display them. A device might have difficulty routing an image if the criteria used are based on free text.

Say that all mammography images are to be routed to a certain workstation. If the attribute in the image can be “breast,” “Breast,” “BREAST,” or “Mammogram,”—or another string—a routing device will hesitate when determining whether the body part meets its routing criteria. But if the SNOMED code for “breast” (T04000) is used, it is uniquely identified and the software will have no problem recognizing it.

View codes are also important, especially for accommodating hanging protocols; those actions taken by a technologist or radiologist to group the films in the required order for optimum review. Here again, if the view code is encoded as an ASCII text string, the system will have a hard time determining how to display the image.

These codes are incorporated in a DICOM image as a multi-element group or sequence containing the coding scheme it came from (SNOMED, LOINC, or a private coding scheme), its version number, and the code itself. Its “meaning” is also included as a text string, which allows a receiver that does not have access to the list of codes to display the text information to a user.

The codes, which are used within DICOM, originate from the SNOMED data dictionary and from such other coding schemes as LOINC. They will be managed by a DICOM working group and published as a separate supplement.

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Miller Freeman, Inc.

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