http://fhir.patientsknowbest.com/codesystem/diagnosticreport-category
https://www.hl7.org/fhir/STU3/codesystem.html
There are several different PKB data types which might be represented in FHIR® as DiagnosticReport resources.
This code set allows these data types to be distinguished.
concept[0]
code = RADIOLOGY
display = Radiology
definition = Radiology