title: A dosimetric comparison of IMRT versus helical tomotherapy for brain tumors.
abstract: OBJECTIVE
  Helical tomotherapy (HT) can deliver highly conformal, uniform doses to the target volume. However, HT can only be delivered in a coplanar mode. The purpose of this study was to perform a dosimetric comparison of HT versus coplanar (cIMRT) and non-coplanar (n-cIMRT) beam arrangements on a conventional linear accelerator in a diverse group of brain tumors.
  
  
  METHODS
  A total of 45 treatment plans were calculated retrospectively for 15 cases. For each case, 3 different delivery techniques (n-cIMRT, cIMRT and HT) were used. The treatment plans were compared using the parameters of the target coverage (conformity index; CI) and homogeneity (HI) for the planning target volume (PTV) and the maximum and mean doses for organs at risk (OARs).
  
  
  RESULTS
  Median HI and CI were the best for HT plans and the worst for cIMRT. The largest reduction of maximum dose for lenses and mean dose for both eyes was achieved for n-cIMRT plans. Mean dose for chiasm and the ipsilateral optic nerve were the lowest for HT. The contralateral optic nerve was most spared with n-cIMRT. For D1% in the brain stem, there was no significant difference between HT and the IMRT plans.
  
  
  CONCLUSIONS
  Both HT and n-cIMRT are capable of producing conformal and homogeneous treatment plans with a good sparing of OARs. However, due to the non-coplanar capabilities of IMRT, n-cIMRT led to a superior dose reduction to the lenses.
authors.affiliation: Department of Medical Physics, Greater Poland Cancer Centre, Garbary 15, 61-866 Poznan, Poland. Electronic address: malgorzata.skorska@wco.pl.
authors.forename: M
authors.initials: M
authors.lastname: Skórska
authors.affiliation: Department of Medical Physics, Greater Poland Cancer Centre, Garbary 15, 61-866 Poznan, Poland; Department of Electroradiology, University of Medical Sciences, Poznan, Poland.
authors.forename: T
authors.initials: T
authors.lastname: Piotrowski
authors.affiliation: Department of Electroradiology, University of Medical Sciences, Poznan, Poland; Department of Radiotherapy II, Greater Poland Cancer Centre, Poznan, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Kaźmierska
authors.affiliation: Second Radiotherapy Ward, Greater Poland Cancer Centre, Poznan, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Adamska
mesh_terms: D001932:Brain Neoplasms / Q000532:radiotherapy*; D006801:Humans; D058958:Organs at Risk / Q000528:radiation effects; D010315:Particle Accelerators; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*
keywords: Brain tumor; Plan comparison; Radiotherapy; Tomotherapy; Treatment planning