GET /api/v2/order_documents returns report, dicom, and invoice when each
exists (null/omitted otherwise). Dedicated routes exist for each document type.
DICOM
Defaultdelivery is base64 (JSON body, zip of the study), which increases
the transferred size of large studies. The base64 delivery mode is
deprecated. Pass delivery=url for a short-lived HTTPS URL (15 minutes).
Scan will not base64-expand studies larger than 500 MB.
Timeouts for the Ambra fetch are 5s connect / 30s read. If the study is missing,
the dedicated DICOM route returns 404.
FHIR ImagingStudy is explicit that instances do not live inside the resource —
use the download URL, not a blob in JSON. See FHIR mapping.