title: Commissioning the neutron production of a Linac: development of a simple tool for second cancer risk estimation.
abstract: OBJECTIVE
  Knowing the contribution of neutron to collateral effects in treatments is both a complex and a mandatory task. This work aims to present an operative procedure for neutron estimates in any facility using a neutron digital detector.
  
  
  METHODS
  The authors' previous work established a linear relationship between the total second cancer risk due to neutrons (TR(n)) and the number of MU of the treatment. Given that the digital detector also presents linearity with MU, its response can be used to determine the TR(n) per unit MU, denoted as m, normally associated to a generic Linac model and radiotherapy facility. Thus, from the number of MU of each patient treatment, the associated risk can be estimated. The feasibility of the procedure was tested by applying it in eight facilities; patients were evaluated as well.
  
  
  RESULTS
  From the reading of the detector under selected irradiation conditions, m values were obtained for different machines, ranging from 0.25 × 10(-4)% per MU for an Elekta Axesse at 10 MV to 6.5 × 10(-4)% per MU for a Varian Clinac at 18 MV. Using these values, TR(n) of patients was estimated in each facility and compared to that from the individual evaluation. Differences were within the range of uncertainty of the authors' methodology of equivalent dose and risk estimations.
  
  
  CONCLUSIONS
  The procedure presented here allows an easy estimation of the second cancer risk due to neutrons for any patient, given the number of MU of the treatment. It will enable the consideration of this information when selecting the optimal treatment for a patient by its implementation in the treatment planning system.
authors.affiliation: Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla 41009, Spain and Departament de Física, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Romero-Expósito
authors.affiliation: Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 4880, Chile.
authors.forename: B
authors.initials: B
authors.lastname: Sánchez-Nieto
authors.affiliation: Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla 41009, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Terrón
authors.affiliation: Serviço de Física Médica, Instituto Português de Oncologia, Coimbra 3000-075, Portugal.
authors.forename: M C
authors.initials: MC
authors.lastname: Lopes
authors.affiliation: i3N, Department of Physics, University of Aveiro, Aveiro 3810-193, Portugal.
authors.forename: B C
authors.initials: BC
authors.lastname: Ferreira
authors.affiliation: Radiotherapy Service, Russian Research Center for Radiology and Surgical Technology, Saint Petersburg 197758, Russian Federation.
authors.forename: D
authors.initials: D
authors.lastname: Grishchuk
authors.affiliation: Elekta, Ltd., Crawley RH10 9RR, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Sandín
authors.affiliation: Servicio de Radiofísica, Instituto Onkologikoa, San Sebastián 20014, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Moral-Sánchez
authors.affiliation: Servicio de Radiofísica, Hospital Universitario de la Ribera, Alzira 46600, Valencia, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Melchor
authors.affiliation: Departament de Física, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Domingo
authors.affiliation: Departamento de Física de Partículas, Universidad de Santiago de Compostela, Santiago de Compostela 15782, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Gómez
authors.affiliation: Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla 41009, Spain and Servicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla 41009, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Sánchez-Doblado
mesh_terms: D005240:Feasibility Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D016609:Neoplasms, Second Primary / Q000453:epidemiology / Q000209:etiology*; D009502:Neutrons / Q000009:adverse effects*; D011874:Radiometry; D016634:Radiosurgery / Q000009:adverse effects*; D012306:Risk