title: Accelerated large volume irradiation with dynamic Jaw/Dynamic Couch Helical Tomotherapy.
abstract: BACKGROUND
  Helical Tomotherapy (HT) has unique capacities for the radiotherapy of large and complicated target volumes. Next generation Dynamic Jaw/Dynamic Couch HT delivery promises faster treatments and reduced exposure of organs at risk due to a reduced dose penumbra.
  
  
  METHODS
  Three challenging clinical situations were chosen for comparison between Regular HT delivery with a field width of 2.5 cm (Reg 2.5) and 5.0 cm (Reg 5.0) and DJDC delivery with a maximum field width of 5.0 cm (DJDC 5.0): Hemithoracic Irradiation, Whole Abdominal Irradiation (WAI) and Total Marrow Irradiation (TMI). For each setting, five CT data sets were chosen, and target coverage, conformity, integral dose, dose exposure of organs at risk (OAR) and treatment time were calculated.
  
  
  RESULTS
  Both Reg 5.0 and DJDC 5.0 achieved a substantial reduction in treatment time while maintaining similar dose coverage. Treatment time could be reduced from 10:57 min to 3:42 min / 5:10 min (Reg 5.0 / DJDC 5.0) for Hemithoracic Irradiation, from 18:03 min to 8:02 min / 8:03 min for WAI and to 18:25 min / 18:03 min for TMI. In Hemithoracic Irradiation, OAR exposure was identical in all modalities. For WAI, Reg 2.5 resulted in lower exposure of liver and bone. DJDC plans showed a small but significant increase of ∼ 1 Gy to the kidneys, the parotid glans and the thyroid gland. While Reg 5.0 and DJDC were identical in terms of OAR exposure, integral dose was substantially lower with DJDC, caused by a smaller dose penumbra.
  
  
  CONCLUSIONS
  Although not clinically available yet, next generation DJDC HT technique is efficient in improving the treatment time while maintaining comparable plan quality.
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, INF 400, 69120, Heidelberg, Germany. sonja.krause@med.uni-heidelberg.de
authors.forename: Sonja
authors.initials: S
authors.lastname: Krause
authors.forename: Sebastian
authors.initials: S
authors.lastname: Beck
authors.forename: Kai
authors.initials: K
authors.lastname: Schubert
authors.forename: Steffen
authors.initials: S
authors.lastname: Lissner
authors.forename: Susanta
authors.initials: S
authors.lastname: Hui
authors.forename: Klaus
authors.initials: K
authors.lastname: Herfarth
authors.forename: Juergen
authors.initials: J
authors.lastname: Debus
authors.forename: Florian
authors.initials: F
authors.lastname: Sterzing
mesh_terms: D000005:Abdomen / Q000528:radiation effects; D001853:Bone Marrow / Q000528:radiation effects; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D013909:Thorax / Q000528:radiation effects; D013997:Time Factors