title: Total marrow irradiation with RapidArc volumetric arc therapy.
abstract: OBJECTIVE
  To develop a volumetric arc therapy (VMAT)-total marrow irradiation (TMI) technique for patients with hematologic malignancies.
  
  
  METHODS
  VMAT planning was performed for 6 patients using RapidArc technology. The planning target volume consisted of all the bones in the body from the head to the mid-femur, excluding the extremities, except for the humerus, plus a 3.0-mm margin. The organs at risk included the lungs, heart, liver, kidneys, bowels, brain, eyes, and oral cavity. The VMAT-TMI technique consisted of three plans: the head and neck, the chest, and the pelvis, each with three 330° arcs. The plans were prescribed to ensure, at a minimum, 95% planning target volume dose coverage with the prescription dose (percentage of volume receiving dose of ≥12 Gy was 95%). The treatments were delivered and verified using MapCheck and ion chamber measurements.
  
  
  RESULTS
  The VMAT-TMI technique reported in the present study provided comparable dose distributions with respect to the fixed gantry linear accelerator intensity-modulated TMI. RapidArc planning was less subjective and easier, and, most importantly, the delivery was more efficient. RapidArc reduced the treatment delivery time to approximately 18 min from 45 min with the fixed gantry linear accelerator intensity-modulated TMI. When the prescription dose coverage was reduced to 85% from 95% and the mandible and maxillary structures were not included in the planning target volume as reported in a tomotherapy study, a considerable organ at risk dose reduction of 4.2-51% was observed. The average median dose for the lungs and lenses was reduced to 5.6 Gy from 7.2 Gy and 2.4 Gy from 4.5 Gy, respectively.
  
  
  CONCLUSIONS
  The RapidArc VMAT technique improved the treatment planning, dose conformality, and, most importantly, treatment delivery efficiency. The results from our study suggest that the RapidArc VMAT technology can be expected to facilitate the clinical transition of TMI.
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago Pritzker School of Medicine, Chicago, IL 60637, USA. baydogan@uchicago.edu
authors.forename: Bulent
authors.initials: B
authors.lastname: Aydogan
authors.forename: Mete
authors.initials: M
authors.lastname: Yeginer
authors.forename: Gulbin O
authors.initials: GO
authors.lastname: Kavak
authors.forename: John
authors.initials: J
authors.lastname: Fan
authors.forename: James A
authors.initials: JA
authors.lastname: Radosevich
authors.forename: Kim
authors.initials: K
authors.lastname: Gwe-Ya
mesh_terms: D000465:Algorithms; D001853:Bone Marrow / Q000528:radiation effects*; D006402:Hematologic Diseases / Q000532:radiotherapy*; D006801:Humans; D058958:Organs at Risk / Q000528:radiation effects; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D014916:Whole-Body Irradiation / Q000379:methods*