title: Biological effectiveness of isolated short electron tracks: V79-4 cell inactivation following low dose-rate irradiation with Al(K) ultrasoft X-rays.
abstract: OBJECTIVE
  To investigate the biological effect of single, isolated, short electron tracks (<70 nm) relevant to practical human exposures to low-linear energy transfer radiation.
  
  
  METHODS
  An irradiation rig was constructed that allowed environmentally controlled, protracted irradiations with an individually prescribed dose to up to 20 samples over a period of days. Inactivation of V79-4 mammalian cells by Al(K) ultrasoft X-rays was studied at high and low dose-rates with a maximum exposure time of 42 h.
  
  
  RESULTS
  A significant increase in clonogenic survival was observed at the higher doses when the exposure time was increased from <6 min to 21 h, with no further increase observed for 42-h exposures. Despite the short range of the low-energy electrons produced (<70 nm), significant cell inactivation was observed for these low dose-rate exposures.
  
  
  CONCLUSIONS
  The results are consistent with the hypothesis that even individual tracks can be biologically effective.
authors.affiliation: MRC Radiation & Genome Stability Unit, Harwell, Didcot OX11 0RD, UK. m.hill@hat.mrc.ac.uk
authors.forename: M A
authors.initials: MA
authors.lastname: Hill
authors.forename: D L
authors.initials: DL
authors.lastname: Stevens
authors.forename: D A
authors.initials: DA
authors.lastname: Bance
authors.forename: D T
authors.initials: DT
authors.lastname: Goodhead
mesh_terms: D000535:Aluminum; D000818:Animals; D002453:Cell Cycle / Q000528:radiation effects*; D002460:Cell Line; D048429:Cell Size / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D006224:Cricetinae; D004307:Dose-Response Relationship, Radiation; D004583:Electrons; D005347:Fibroblasts / Q000166:cytology / Q000528:radiation effects*; D018499:Linear Energy Transfer; D018613:Microscopy, Confocal; D016012:Poisson Distribution; D011829:Radiation Dosage; D012062:Relative Biological Effectiveness; D013997:Time Factors; D014965:X-Rays
chemical_list: D000535:Aluminum