title: Optimising the dosimetric quality and efficiency of post-prostatectomy radiotherapy: a planning study comparing the performance of volumetric-modulated arc therapy (VMAT) with an optimised seven-field intensity-modulated radiotherapy (IMRT) technique.
abstract: OBJECTIVE
  The purpose of this study was to compare and evaluate radiotherapy treatment plans using volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) for post-prostatectomy radiotherapy.
  
  
  METHODS
  The quality of radiotherapy plans for 10 patients planned and treated with a seven-field IMRT technique for biochemical failure post-prostatectomy were subsequently compared with 10 prospectively planned single-arc VMAT plans using the same computed tomography data set and treatment planning software. Plans were analysed using parameters to assess for target volume coverage, dose to organs at risk (OAR), biological outcomes, dose conformity and homogeneity, as well as the total monitor units (MU), planning and treatment efficiency.
  
  
  RESULTS
  The mean results for the study population are reported for the purpose of comparison. For IMRT, the median dose to the planning target volume, V(95%) and D(95%) was 71.1 Gy, 98.9% and 68.3 Gy compared with 71.2 Gy, 99.2% and 68.6 Gy for VMAT. There was no significant difference in the conformity index or homogeneity index. The VMAT plans achieved better sparing of the rectum and the left and right femora with a reduction in the median dose by 7.9, 6.3 and 3.6 Gy, respectively. The total number of monitor units (MU) was reduced by 24% and treatment delivery time by an estimated 3 min per fraction without a significant increase in planning requirements.
  
  
  CONCLUSIONS
  VMAT can achieve post-prostatectomy radiotherapy plans of comparable quality to IMRT with the potential to reduce dose to OAR and improve the efficiency of treatment delivery.
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Locked Bag 1, A’Beckett Street, Vic. 8006, Australia. btnguyen321@yahoo.com.au
authors.forename: Brandon T
authors.initials: BT
authors.lastname: Nguyen
authors.forename: Colin
authors.initials: C
authors.lastname: Hornby
authors.forename: Tomas
authors.initials: T
authors.lastname: Kron
authors.forename: Jim
authors.initials: J
authors.lastname: Cramb
authors.forename: Aldo
authors.initials: A
authors.lastname: Rolfo
authors.forename: Daniel
authors.initials: D
authors.lastname: Pham
authors.forename: Annette
authors.initials: A
authors.lastname: Haworth
authors.forename: Keen-Hun
authors.initials: KH
authors.lastname: Tai
authors.forename: Farshad
authors.initials: F
authors.lastname: Foroudi
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk; D018579:Patient Selection; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed