def add_angle(item, angle_tag, direction_tag, angle, direction, current_angle)
      if !self.send(current_angle) || angle != self.send(current_angle)
        self.send("#{current_angle}=", angle)
        DICOM::Element.new(angle_tag, angle, :parent => item)
        DICOM::Element.new(direction_tag, (direction.empty? ? 'NONE' : direction), :parent => item)
      end
    end
def add_angle(item, angle_tag, direction_tag, angle, direction, current_angle)
      if !self.send(current_angle) || angle != self.send(current_angle)
        self.send("#{current_angle}=", angle)
        DICOM::Element.new(angle_tag, angle, :parent => item)
        DICOM::Element.new(direction_tag, (direction.empty? ? 'NONE' : direction), :parent => item)
      end
    end
Adds an angular type value to a Control Point Item, by creating the
 necessary DICOM elements.
 Note that the element is only added if there is no 'current' attribute
 defined, or the given value is different form the current attribute.

 @param [DICOM::Item] item the DICOM control point item in which to create the elements
 @param [String] angle_tag the DICOM tag of the angle element
 @param [String] direction_tag the DICOM tag of the direction element
 @param [String, NilClass] angle the collimator angle attribute
 @param [String, NilClass] direction the collimator rotation direction attribute
 @param [Symbol] current_angle the instance variable that keeps track of the current value of this attribute