title: Modelling of cell killing due to sparsely ionizing radiation in normoxic and hypoxic conditions and an extension to high LET radiation.
abstract: OBJECTIVE
  An approach for describing cell killing with sparsely ionizing radiation in normoxic and hypoxic conditions based on the initial number of randomly distributed DNA double-strand breaks (DSB) is proposed. An extension of the model to high linear energy transfer (LET) radiation is also presented.
  
  
  METHODS
  The model is based on the probabilities that a given DNA giant loop has one DSB or at least two DSB. A linear combination of these two classes of damage gives the mean number of lethal lesions. When coupled with a proper modelling of the spatial distribution of DSB from ion tracks, the formalism can be used to predict cell response to high LET radiation in aerobic conditions.
  
  
  RESULTS
  Survival data for sparsely ionizing radiation of cell lines in normoxic/hypoxic conditions were satisfactorily fitted with the proposed parametrization. It is shown that for dose ranges up to about 10 Gy, the model describes tested experimental survival data as good as the linear-quadratic model does. The high LET extension yields a reasonable agreement with data in aerobic conditions.
  
  
  CONCLUSIONS
  A new survival model has been introduced that is able to describe the most relevant features of cellular dose-response postulating two damage classes.
authors.affiliation: Centro Nazionale di Adroterapia Oncologica , Pavia , Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mairani
authors.forename: Till T
authors.initials: TT
authors.lastname: Böhlen
authors.forename: Ivana
authors.initials: I
authors.lastname: Dokic
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Cabal
authors.forename: Stephan
authors.initials: S
authors.lastname: Brons
authors.forename: Thomas
authors.initials: T
authors.lastname: Haberer
mesh_terms: D016923:Cell Death / Q000528:radiation effects; D015687:Cell Hypoxia / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D018499:Linear Energy Transfer; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism*; D011336:Probability
chemical_list: D010100:Oxygen