There are a lot of extensions defined in this IG with scopes of a variety of resources, as well as the generic Extension data type.  Most of these scopes are not appropriate.  For example, https://hl7.org/fhir/us/codex-radiation-therapy/StructureDefinition-codexrt-radiotherapy-fractions-delivered.html is defined as the amount actually delivered.  As such, it should never appear on definition or request resources.  Only those resources where the IG expects the extension to actually be used should appear as a scope.

The generic Extension data type should NEVER be a scope for an extension, as that's saying this extension is something that would be appropriate to appear on any extension at all.  If this is appropriate to appear in the context of other extensions, those extensions should be enumerated explicitly by URL.  If new extensions are developed where this content might also be relevant, those can be introduced in a future version of the IG.