title: [The effect of the time interval between fractions on the result of a fractionated irradiation of the R1H tumor].
abstract: BACKGROUND
  The response of an experimental tumor to hyperfractionated irradiation with different time intervals between the two daily fractions has been investigated.
  
  
  METHODS
  Tumors were exposed to irradiation five days per week over six weeks. A standard treatment of 30 fractions, i.e. one fraction per day (200 kVp X-rays) was compared with a hyperfractionated schedule of 60 fractions, i.e. two fractions per day, with time intervals of either one, two, three, five or six hours between the two daily fractions.
  
  
  RESULTS
  Compared with standard treatment a significant reduction (p < 0.005) of net growth delay was observed for the tumors treated with two daily fractions separated by two hours. However, at a time interval of five and six hours between the two daily fractions net growth delay increased considerably (p < 0.0001 and p < 0.01) as compared with the standard treatment.
  
  
  CONCLUSIONS
  Our results indicate the importance of the time interval between the daily fractions in hyperfractionated and accelerated radiotherapy.
authors.affiliation: Institut für Biophysik und Strahlenbiologie, Universität Hamburg.
authors.forename: H P
authors.initials: HP
authors.lastname: Beck-Bornholdt
authors.forename: M
authors.initials: M
authors.lastname: Kleineidam
authors.forename: A
authors.initials: A
authors.lastname: Pieconka
mesh_terms: D000818:Animals; D011879:Radiotherapy Dosage; D051381:Rats; D012208:Rhabdomyosarcoma / Q000532:radiotherapy*; D013997:Time Factors
vernacular_title: Einfluss des Zeitintervalls zwischen den Fraktionen auf das Ergebnis einer fraktionierten Bestrahlung des R1H-Tumors.