title: A universal dose-response curve for radiochromic films.
abstract: OBJECTIVE
  This paper presents a model for dose-response curves of radiochromic films. It is based on a modified version of single-hit model to take into account the growth experienced by lithium salt of pentacosa-10,12-diynoic acid polymers after irradiation.
  
  
  METHODS
  Polymer growth in radiochromic films is a critical phenomenon that can be properly described by means of percolation theory to provide an appropriate distribution function for polymer sizes. Resulting functional form is a power function featuring a critical exponent and two adjustable parameters. Moreover, these parameters act as scaling factors setting a natural scale for sensitometric curves where the dependence on channel sensitivity is removed. A unique reduced response curve is then obtained from all the color channels describing film behavior independently of film dosimetry system.
  
  
  RESULTS
  Resulting functional form has been successfully tested in several sensitometric curves from different Gafchromic EBT models, providing excellent agreement with experimental data in a wide dose range up to about 40 Gy and low dose uncertainty.
  
  
  CONCLUSIONS
  The model presented in this paper describes accurately the sensitometric curves of radiochromic films in wide dose ranges covering all typical ranges used in external radiotherapy. Resulting dose uncertainty is low enough to render a reasonably good performance in clinical applications. Due to cross-correlation, only one of the adjustable parameters is totally independent and characterizes film batches.
authors.affiliation: Radiofísica Hospitalaria, Hospital Regional Universitario, Málaga 29010, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Martín-Viera Cueto
authors.affiliation: Radiofísica Hospitalaria, Hospital Regional Universitario, Málaga 29010, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Parra Osorio
authors.affiliation: Radiofísica Hospitalaria, Hospital Regional Universitario, Málaga 29010, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Moreno Sáiz
authors.affiliation: Radiofísica Hospitalaria, Hospital Regional Universitario, Málaga 29010, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Navarro Guirado
authors.affiliation: Radiofísica Hospitalaria, Hospital Regional Universitario, Málaga 29010, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Casado Villalón
authors.affiliation: Radiofísica Hospitalaria, Hospital Regional Universitario, Málaga 29010, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Galán Montenegro
mesh_terms: D000465:Algorithms; D005373:Film Dosimetry; D008962:Models, Theoretical; D035501:Uncertainty