title: Influence of multi-leaf collimator leaf width in radiosurgery via volumetric modulated arc therapy and 3D dynamic conformal arc therapy.
abstract: OBJECTIVE
  To study the influence of Multileaf Collimator (MLC) leaf width in radiosurgery treatment planning for Volumetric Modulated Arc Therapy (VMAT) and 3D Dynamic Conformal Arc Therapy (3D-DCA).
  
  
  METHODS
  16 patients with solitary brain metastases treated with radiosurgery via the non-coplanar VMAT were replanned for the 3D-DCA. For each planning technique two MLC leaf width sizes were utilized, i.e. 5 mm and 2.5 mm. These treatment plans were compared using dosimetric indices (conformity, gradient and mean dose for brain tissue) and the normal tissue complication probability (NTCP).
  
  
  RESULTS
  An improvement in planning quality for VMAT was observed versus 3D-DCA for any MLC leaf width, mainly with regards to dose conformity and to a lesser extent regards dose gradient. No significant difference was observed for any of both techniques using smaller leaf width. However, dose gradient was improved in favor of the 2.5 mm MLC for either of both techniques (15% VMAT and 10% 3D-DCA); being noticeable for lesions smaller than 10cm(3). Nonetheless, the NTCP index was not significantly affected by variations in the dose gradient index.
  
  
  CONCLUSIONS
  This, our present study, suggests that the use of an MLC leaf width of 2.5 mm via the noncoplanar VMAT and 3D-DCA techniques provides improvement in terms of dose gradient for small volumes, over those results obtained with an MLC leaf width of 5 mm. The 3D-DCA does also benefit from MLC leaf widths of a smaller size, mainly in terms of conformity.
authors.affiliation: Medical Physics and Radiation Protection Department, Santa Lucia University Hospital, 30202 Cartagena, Murcia, Spain. Electronic address: alfredo.serna@carm.es.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Serna
authors.affiliation: Medical Physics and Radiation Protection Department, Santa Lucia University Hospital, 30202 Cartagena, Murcia, Spain.
authors.forename: Vicente
authors.initials: V
authors.lastname: Puchades
authors.affiliation: Medical Physics and Radiation Protection Department, Santa Lucia University Hospital, 30202 Cartagena, Murcia, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Mata
authors.affiliation: Medical Physics and Radiation Protection Department, Santa Lucia University Hospital, 30202 Cartagena, Murcia, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Ramos
authors.affiliation: Medical Physic Radiology and Physical Medicine Department, Faculty of Medicine, University of Murcia, 30100 Espinardo, Murcia, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Alcaraz
mesh_terms: D001932:Brain Neoplasms / Q000532:radiotherapy / Q000556:secondary / Q000601:surgery; D006801:Humans; D011874:Radiometry; D016634:Radiosurgery / Q000295:instrumentation / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000295:instrumentation / Q000379:methods*
keywords: Brain metastases; Conformal arc therapy; Leaf size; Radiosurgery; VMAT