title: Three-dimensional conformal radiotherapy, static intensity-modulated and helical intensity-modulated radiotherapy in glioblastoma. Dosimetric comparison in patients with overlap between target volumes and organs at risk.
abstract: OBJECTIVE
  Radiotherapy is the standard treatment of glioblastoma. Three-dimensional conformal radiotherapy is the standard technique to treat glioblastoma. Intensity-modulated radiotherapy and helical intensity-modulated radiotherapy (tomotherapy) are becoming widely used. The present study compared three-dimensional conformal radiotherapy, intensity-modulated radiotherapy and tomotherapy in terms of target coverage and preservation of organs at risk.
  
  
  METHODS
  Ten patients treated with three-dimensional conformal radiotherapy, with a target volume close to or superimposed to the organs at risk, were retrospectively selected. The plans were re-planned with step-and-shoot 3/5 fields intensity-modulated radiotherapy and tomotherapy. Target coverage and sparing of organs at risk were statistically compared.
  
  
  RESULTS
  Mean planning target volume V95% improved with sophisticated techniques (87.2%, 93.2%, 97.6% with three-dimensional conformal radiotherapy, intensity-modulated radiotherapy and tomotherapy, respectively). The comparison of three-dimensional conformal radiotherapy and intensity-modulated radiotherapy did not show significant differences, whereas differences were significant when three-dimensional conformal radiotherapy and tomotherapy as well as intensity-modulated radiotherapy and tomotherapy were compared. Mean planning target volume/clinical target volume D99-D98-D95 were not different between three-dimensional conformal radiotherapy and intensity-modulated radiotherapy, but they were different between tomotherapy and three-dimensional conformal radiotherapy and intensity-modulated radiotherapy, with better clinical target volume/and planning target volume coverage with the tomotherapy plans. Brain D33/66 were 31.1/11.8 Gy, 37.5/18.3 Gy and 28.5/14.7 Gy with three-dimensional conformal radiotherapy, intensity-modulated radiotherapy and tomotherapy, respectively. Mean brainstem, optic nerves and chiasma Dmax were always within the defined constraints. The homogeneity index improved with intensity-modulated radiotherapy/tomotherapy compared to three-dimensional conformal radiotherapy. Tomotherapy was better than intensity-modulated radiotherapy in all patients.
  
  
  CONCLUSIONS
  In this selected group of patients, a significant dosimetric advantage was evident for tomotherapy compared with three-dimensional conformal radiotherapy and intensity-modulated radiotherapy. Significant advantages were evident in terms of panning target volume coverage (V95), D99, D98 and D95. The clinical significance of the results should be defined.
authors: Michela
authors: M
authors: Buglione
authors: Luigi
authors: L
authors: Spiazzi
authors: Federica
authors: F
authors: Saiani
authors: Loredana
authors: L
authors: Costa
authors: Blerina
authors: B
authors: Shehi
authors: Barbara
authors: B
authors: Lazzari
authors: Chiara
authors: C
authors: Uccelli
authors: Nadia
authors: N
authors: Pasinetti
authors: Paolo
authors: P
authors: Borghetti
authors: Luca
authors: L
authors: Triggiani
authors: Laura
authors: L
authors: Donadoni
authors: Sara
authors: S
authors: Pedretti
authors: Stefano M
authors: SM
authors: Magrini
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000532:radiotherapy*; D005260:Female; D005909:Glioblastoma / Q000532:radiotherapy*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007558:Italy; D008297:Male; D008875:Middle Aged; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000009:adverse effects* / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome