def add_isosenter(site_setup, item)
      if site_setup
        # Create an element if the value is new or unique:
        if !@current_isosenter
          iso = "#{(site_setup.iso_pos_x.to_f * 10).round(2)}\\#{(site_setup.iso_pos_y.to_f * 10).round(2)}\\#{(site_setup.iso_pos_z.to_f * 10).round(2)}"
          if iso != @current_isosenter
            @current_isosenter = iso
            DICOM::Element.new('300A,012C', iso, :parent => item)
          end
        end
      else
        # Log a warning if this is the first control point:
        unless @current_isosenter
          logger.warn("No Site Setup record exists for this plan. Unable to provide an isosenter position.")
        end
      end
    end
def add_isosenter(site_setup, item)
      if site_setup
        # Create an element if the value is new or unique:
        if !@current_isosenter
          iso = "#{(site_setup.iso_pos_x.to_f * 10).round(2)}\\#{(site_setup.iso_pos_y.to_f * 10).round(2)}\\#{(site_setup.iso_pos_z.to_f * 10).round(2)}"
          if iso != @current_isosenter
            @current_isosenter = iso
            DICOM::Element.new('300A,012C', iso, :parent => item)
          end
        end
      else
        # Log a warning if this is the first control point:
        unless @current_isosenter
          logger.warn("No Site Setup record exists for this plan. Unable to provide an isosenter position.")
        end
      end
    end
Adds an Isosenter element to a Control Point Item.
 Note that the element is only added if there is a Site Setup record present,
 and it contains a real (non-empty) value. Also, the element is only added if there
 is no 'current' attribute defined, or the given value is different form the current attribute.

 @param [SiteSetup, NilClass] site_setup the associated site setup record
 @param [DICOM::Item] item the DICOM control point item in which to create an element