Deriving absolute values of alpha and beta for dose fractionation, using dose-incidence data.
A method is described for calculating absolute "operational" values of the parameters alpha and beta that characterise dose fractionation data for tissues, by using the steepness of dose-incidence curves measured around each dose per fraction investigated. The values are deduced from published mouse lethality data after irradiation of the bone marrow (alpha = 0.9 Gy-1; beta = 0.06 Gy-2), the lung (alpha = 0.14 Gy-1; beta = 0.02 Gy-2), and the oesophagus (alpha = 0.06 Gy-1; beta = 0.004 Gy-2). With bone marrow and other hierarchical renewal tissues, the operational values apply also to the inactivation of target cells which are the stem cells in the tissue. For other tissue types the interpretation of the values is unknown. The operational values are useful in characterising the steepness of dose-incidence curves for normal tissue injury after different fractionation schedules.
D000818:Animals; D002470:Cell Survival / Q000528:radiation effects*; D051379:Mice; D011829:Radiation Dosage