def add(dcm)
      raise ArgumentError, "Invalid argument 'dcm'. Expected DObject, got #{dcm.class}." unless dcm.is_a?(DICOM::DObject)
      DoseVolume.load(dcm, self) if proper_dose_volume?(dcm)
    end
def add(dcm)
      raise ArgumentError, "Invalid argument 'dcm'. Expected DObject, got #{dcm.class}." unless dcm.is_a?(DICOM::DObject)
      DoseVolume.load(dcm, self) if proper_dose_volume?(dcm)
    end
Registers a DICOM Object to the RTDose series, and processes it to create
 (and reference) a DoseVolume instance linked to this RTDose series.

 @param [DICOM::DObject] dcm an RTDOSE DICOM object