title: Volumetric modulated arc therapy with simultaneous integrated boost for locally advanced rectal cancer.
abstract: OBJECTIVE
  To report the feasibility of volumetric modulated arc therapy (VMAT) for neoadjuvant radiotherapy in locally advanced rectal cancer in a dose-escalation protocol and simultaneous integrated boost (SIB) approach. Moreover, the VMAT technique was compared with three-dimensional conformal radiotherapy (3D-CRT) and fixed-field intensity modulated radiotherapy (IMRT), in terms of target coverage and irradiation of organs at risk.
  
  
  METHODS
  Eight patients with locally advanced rectal cancer were treated with the SIB-VMAT technique. The VMAT plans were compared with 3D-CRT and IMRT techniques in terms of several clinically dosimetric parameters. The number of monitor units and the delivery time were analysed to score the treatment efficiency. All plans were verified in a dedicated solid water phantom using a two-dimensional array of ionisation chambers.
  
  
  RESULTS
  All techniques meet the prescription goal for planning target volume coverage, with VMAT showing the highest level of conformality. VMAT is associated with 40, 53 and 58% reduction in the percentage of volume of small bowel irradiated to 30, 40 and 50Gy, compared with 3D-CRT. No significant differences were found with respect to SIB-IMRT. VMAT plans showed a significant reduction of monitor units by nearly 20% with respect to IMRT and reduced treatment time from 14 to 5min for a single fraction.
  
  
  CONCLUSIONS
  SIB-VMAT plans can be planned and carried out with high quality and efficiency for rectal cancer, providing similar sparing of organs at risk to SIB-IMRT and resulting in the most efficient treatment option. SIB-VMAT is currently our standard approach for radiotherapy of locally advanced rectal cancer.
authors.affiliation: Medical Physics Unit, "John Paul II" Center for High Technology Research and Education in Biomedical Sciences, Catholic University, Campobasso, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Cilla
authors.forename: L
authors.initials: L
authors.lastname: Caravatta
authors.forename: V
authors.initials: V
authors.lastname: Picardi
authors.forename: D
authors.initials: D
authors.lastname: Sabatino
authors.forename: G
authors.initials: G
authors.lastname: Macchia
authors.forename: C
authors.initials: C
authors.lastname: Digesù
authors.forename: F
authors.initials: F
authors.lastname: Deodato
authors.forename: M
authors.initials: M
authors.lastname: Massaccesi
authors.forename: M
authors.initials: M
authors.lastname: De Spirito
authors.forename: A
authors.initials: A
authors.lastname: Piermattei
authors.forename: A G
authors.initials: AG
authors.lastname: Morganti
mesh_terms: D000368:Aged; D006801:Humans; D008875:Middle Aged; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012004:Rectal Neoplasms / Q000532:radiotherapy*