title: Helical tomotherapy-based hypofractionated radiotherapy for prostate cancer: a report on the procedure, dosimetry and preliminary clinical outcome.
abstract: BACKGROUND
  Hypofractionated intensity-modulated radiotherapy (IMRT) under image guidance using helical tomotherapy for prostate cancer improves therapeutic ratio.
  
  
  OBJECTIVE
  To report on clinical and dosimetric experience using hypofractionated helical tomotherapy for prostate cancer.
  
  
  METHODS
  Prospective consecutive case series as feasibility study approved by Institutional Review Board (IRB) (2007-11).
  
  
  METHODS
  The staging work-up, risk stratification, simulation, contouring, planning, online matching and treatment delivery methodology are described in detail. The doses to (prostate and nodal) PTV and organs at risk (bladder, rectum, bowel and femoral heads) are described. The audit of online matching was used to determine set-up errors, PTV margins and resultant translational vector. We also report the outcomes in terms of biochemical relapse-free survival and acute toxicity.
  
  
  RESULTS
  Fifty-three consecutive patients were included. The baseline PSA was 23 ng/ml (1.60-100.37). The prostate BED3 ranged from 110-129 Gy (α/β for prostate 1.5-3 Gy) and nodal 72-87.68 Gy. The required PTV margin by van Hark's formula for lateral, longitudinal and vertical axes were 11.30, 9.95 and 13.49 mm, respectively with resultant vectors 3-15 mm. There was 7% to 8% chance of missing part of CTV in absence of image guidance. There was only one patient requiring premature conclusion at 45 Gy due grade 3 genitourinary toxicity. At median follow-up of 23 months, biochemical relapse-free survival rate is 95.2%.
  
  
  CONCLUSIONS
  Hypofractionated IMRT under image guidance using helical tomotherapy for prostate cancer is feasible with acceptable acute toxicity and may be advantageous in high throughput centers.
authors.affiliation: Department of Radiation Oncology, Tata Memorial Hospital, Mumbai, India.
authors.forename: Vedang
authors.initials: V
authors.lastname: Murthy
authors.forename: Rahul
authors.initials: R
authors.lastname: Krishnatry
authors.forename: Suman
authors.initials: S
authors.lastname: Mallik
authors.forename: Zubin
authors.initials: Z
authors.lastname: Master
authors.forename: Umesh
authors.initials: U
authors.lastname: Mahantshetty
authors.forename: Shyamkishore
authors.initials: S
authors.lastname: Shrivastava
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D005240:Feasibility Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D016032:Randomized Controlled Trials as Topic