The Media resource captures a specific type of Observation – an Observation whose value is audio, video or image data. This resource is the preferred representation of such forms of information as it exposes the metadata relevant for interpreting the information. However, in some legacy environments, media information may occasionally appear in Observation instead. Systems should be aware of this possibility.
The Media resource is able to contain medical images in a Digital Imaging and COmmunications in Medicine (DICOM) format. These images may also be made accessible through an ImagingStudy resource, which provides a direct reference to the image to a Web Access to DICOM Objects (WADO)-RS server.
For such images, the WADO-RS framework is a preferred method for representing the images – the WADO-RS service may include rendering the image with annotations and display parameters from an associated DICOM presentation state, for instance.
On the other hand, the media resource allows for a robust transfer of an image across boundaries where the WADO-RS service is not available. For this reason, medical images can also be represented in a Media resource, but the Media.content.url should provide a reference to a source WADO-RS service for the image.