def print_rt
      @patients.each do |p|
        puts p.name
        p.studies.each do |st|
          puts "  Study (UID: #{st.uid})"
          st.image_series.each do |is|
            puts "    #{is.modality} (#{is.images.length} images - UID: #{is.uid})"
            is.structs.each do |struct|
              puts "      StructureSet (#{struct.rois.length} ROIs - UID: #{struct.uid})"
              struct.plans.each do |plan|
                puts "        RTPlan (#{plan.beams.length} beams - UID: #{plan.uid})"
                plan.rt_doses.each do |rt_dose|
                  puts "          RTDose (#{rt_dose.volumes.length} volumes - UID: #{rt_dose.uid})"
                end
                plan.rt_images.each do |rt_image|
                  puts "          RTImage (#{rt_image.images.length} images - UID: #{rt_image.uid})"
                end
              end
            end
          end
        end
      end
    end
def print_rt
      @patients.each do |p|
        puts p.name
        p.studies.each do |st|
          puts "  Study (UID: #{st.uid})"
          st.image_series.each do |is|
            puts "    #{is.modality} (#{is.images.length} images - UID: #{is.uid})"
            is.structs.each do |struct|
              puts "      StructureSet (#{struct.rois.length} ROIs - UID: #{struct.uid})"
              struct.plans.each do |plan|
                puts "        RTPlan (#{plan.beams.length} beams - UID: #{plan.uid})"
                plan.rt_doses.each do |rt_dose|
                  puts "          RTDose (#{rt_dose.volumes.length} volumes - UID: #{rt_dose.uid})"
                end
                plan.rt_images.each do |rt_image|
                  puts "          RTImage (#{rt_image.images.length} images - UID: #{rt_image.uid})"
                end
              end
            end
          end
        end
      end
    end
Prints the nested structure of the DataSet from a radiotherapy point of
 view, where the various series beneath the patient-study level is presented
 in a hiearchy of image series, structure set, rt plan, rt dose and rt image,
 in accordance with the object hiearchy used by RTKIT.