It must be clear that the delivered dose to a volume in a Treatment Phase is only dose from this phase, and does not include previous phases, i.e. it is not the running total up to this phase, which could be expected in cases where phases are sequential. This is already to some degree covered with the explanation of totalDoseDelivered in the extension Dose Delivered to Volume, which already says: *"*The total amount of radiation delivered to this volume within the scope of this dose delivery." We should clarify in Teleradiotherapy Treatment Phase and Brachytherapy Treatment Phase http://hl7.org/fhir/us/mcode/2021May/StructureDefinition-mcode-teleradiotherapy-treatment-phase-definitions.html#Procedure.extension:doseDeliveredToVolume.extension:totalDoseDelivered and the respective element description in the Brachy Phase http://hl7.org/fhir/us/mcode/2021May/StructureDefinition-mcode-brachytherapy-treatment-phase-definitions.html#Procedure.extension:doseDeliveredToVolume  that this summarizes dose only from this phase that is represented by the Procedure, not up to this phase. Suggested Definition: "The total amount of radiation delivered to this volume within the scope of this phase, not including dose from any other phase. For summary over multiple phases, see Radiotherapy Course Summary."

Maybe in the extension http://hl7.org/fhir/us/mcode/2021May/StructureDefinition-mcode-radiotherapy-dose-delivered-to-volume-definitions.html#Extension.extension:totalDoseDelivered "The total amount of radiation delivered to this volume within the scope of this dose delivery" add "i.e. dose delivered from the Procedure in which this extension is used."