title: Clonogenic survival of human keratinocytes and rodent fibroblasts after irradiation with 25 kV x-rays.
abstract: Low energy x-rays (E(ph) </=50 keV) are widely used in diagnostic radiology and radiotherapy. However, data on their relative biological effectiveness (RBE) are scarce. Of particular importance for risk estimation are the RBE values of x-rays in the range which is commonly used in mammography (10-30 keV). We have determined clonogenic survival after low-energy x-ray irradiation for three cell lines: primary human epidermal keratinocytes (HEKn), mouse fibroblasts (NIH/3T3) and Chinese hamster fibroblasts (V79). Experiments were performed with a 25 kV x-ray tube and compared to 200 kV x-rays as a reference. Compared to the effect of 200 kV x-rays, irradiation with 25 kV x-rays resulted in a decreased survival rate in the murine fibroblasts, but not in the human epithelial cell line. The RBE value was calculated for 10% surviving fraction. For HEKn cells, RBE was 1.33+/-0.27, for NIH/3T3 cells 1.25+/-0.07 and for V79 cells 1.10+/-0.09, respectively. No consistently increased RBE was observed in the various cell lines. Nevertheless, a potential of increased cytogenetic changes has to be considered for risk estimation of low-energy x-rays.
authors.affiliation: Institute of Nuclear and Hadron Physics, Forschungszentrum Rossendorf, P.O. Box 510119, 01314 Dresden, Germany. A.Panteleeva@fz-rossendorf.de
authors.forename: Anna
authors.initials: A
authors.lastname: Panteleeva
authors.forename: Dorota
authors.initials: D
authors.lastname: Słonina
authors.forename: Katarina
authors.initials: K
authors.lastname: Brankovic
authors.forename: Kathrin
authors.initials: K
authors.lastname: Spekl
authors.forename: Jörg
authors.initials: J
authors.lastname: Pawelke
authors.forename: Cordelia
authors.initials: C
authors.lastname: Hoinkis
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Dörr
mesh_terms: D016475:3T3 Cells / Q000528:radiation effects*; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D006224:Cricetinae; D005347:Fibroblasts / Q000528:radiation effects*; D006801:Humans; D015603:Keratinocytes / Q000528:radiation effects*; D008327:Mammography / Q000592:standards; D051379:Mice; D011874:Radiometry / Q000592:standards*; D012062:Relative Biological Effectiveness; D018570:Risk Assessment