This is the ValueSet that contains all the codes in Isotopes Value Set (http://hl7.org/fhir/uv/radiation-dose-summary/ValueSet/isotope-rds-vs) and Isotopes Value Set (http://hl7.org/fhir/uv/radiation-dose-summary/ValueSet/isotope-rds-vs). E.g. what you have to deal with if you get resources containing codes in either of them