def add_rt_dose(rt_dose)
      raise ArgumentError, "Invalid argument 'rt_dose'. Expected RTDose, got #{rt_dose.class}." unless rt_dose.is_a?(RTDose)
      @rt_doses << rt_dose unless @associated_rt_doses[rt_dose.uid]
      @associated_rt_doses[rt_dose.uid] = rt_dose
    end
def add_rt_dose(rt_dose)
      raise ArgumentError, "Invalid argument 'rt_dose'. Expected RTDose, got #{rt_dose.class}." unless rt_dose.is_a?(RTDose)
      @rt_doses << rt_dose unless @associated_rt_doses[rt_dose.uid]
      @associated_rt_doses[rt_dose.uid] = rt_dose
    end
Adds a RTDose series to this Plan.

 @param [RTDose] rt_dose an RTDose instance to be associated with this plan