title: Comparison of deliverable IMRT and VMAT for spine metastases using a simultaneous integrated boost.
abstract: OBJECTIVE
  To effectively treat spine metastases, significant dose must be delivered to regions surrounding the spinal cord. We present a study comparing both step-and-shoot intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques to deliver a concomitant hypofractionated prescription dose to the diseased region and to the involved vertebrae.
  
  
  METHODS
  Seven-field IMRT and a single arc VMAT were inversely planned on five (two cervical and three thoracic) spinal metastatic patients. Planning target volumes PTVm (macroscopic) and PTVe (elective involved vertebrae) and associated organs at risk were localised. Mean doses of 35 Gy to PTVm and 20 Gy to PTVe were prescribed in five fractions. Dose statistics, estimated delivery time and results of verification using Delta(4) (ScandiDos, Uppsala, Sweden) were compared.
  
  
  RESULTS
  Deliverable plans were achieved with both IMRT and VMAT. The coverage to PTV was similar for both IMRT and VMAT (p=0.5) and the dose to the regions adjacent to the spinal cord was 1% higher with VMAT (p=0.04). The mean delivery time for VMAT was 3.5 min compared with 10.5 min for IMRT. Fewer monitor units were required to deliver IMRT than to deliver VMAT. The median (range) percentage of measured points with a γ-index <1 with 3%/3 mm was 100 (99.9-100)% for IMRT and 100 (88.5-100)% for VMAT.
  
  
  CONCLUSIONS
  Both VMAT and IMRT can deliver the concomitant hypofractionated regime proposed, and both offer different benefits in dose delivery. IMRT is currently preferred for its superior pre-treatment verification results and shorter planning times.
  
  
  CONCLUSIONS
  This study explores the feasibility of delivering tumouricidal doses of radiation to metastatic spine disease in the vicinity of the spinal cord.
authors: Joint Department of Physics, The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, UK. young.lee@rmh.nhs.uk
authors: Y K
authors: YK
authors: Lee
authors: J L
authors: JL
authors: Bedford
authors: H A
authors: HA
authors: McNair
authors: M A
authors: MA
authors: Hawkins
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae; D005240:Feasibility Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D013125:Spinal Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D013904:Thoracic Vertebrae; D014057:Tomography, X-Ray Computed
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