title: Mammalian cell survival studies characterizing multiport negative pi-meson irradiation with the Stanford Medical Pion Generator (SMPG).
abstract: Radiobiological measurements have been made under various conditions of muliport pion irradiation using the Stanford Medical Pion Generator (SMPG). Chinese hamster cells (HA-1) were suspended in a tissue-equivalent 25% gelatin/medium solution. Hypoxic and aerobic HA-1 cells were irradiated simultaneously in a cylindrical water tank at either 4 or 16 degrees C. Irradiation at the focus of 60 converging pion beams, at a peak dose rate of 6 rads/min, gave relative biological effectiveness (RBEs) of 2.8, 1.8 and 1.4 at 50, 20 and 5% survival, respectively, and an oxygen enhancement ratio (OER) of 1.7. Plateau irradiation with crossing pion beams, at a peak dose-rate of 3 rads/min, resulted in survival values very close to those obtained with similar doses of 85 kV X-rays. Preliminary studies with large irradiation volumes in broadened pion stopping regions indicate RBEs significantly > 1 for survival > 50%. Supporting microdosimetric data with the SMPG are consistent with the radiobiological results.
authors.affiliation: Department of Radiology, Stanford University School of Medicine, CA 94305.
authors.forename: G C
authors.initials: GC
authors.lastname: Li
authors.forename: P
authors.initials: P
authors.lastname: Fessenden
authors.forename: G M
authors.initials: GM
authors.lastname: Hahn
authors.forename: G
authors.initials: G
authors.lastname: Fisher
authors.forename: G
authors.initials: G
authors.lastname: Luxton
authors.forename: M A
authors.initials: MA
authors.lastname: Bagshaw
mesh_terms: D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects*; D006224:Cricetinae; D006801:Humans; D008651:Mesons; D008961:Models, Structural; D009369:Neoplasms / Q000532:radiotherapy; D012062:Relative Biological Effectiveness