A COMPARISON OF EXPERIMENTAL AND CALCULATED SURVIVAL CURVES FOR V79 CELLS GROWN AS MONOLAYERS OR IN SUSPENSION EXPOSED TO ALPHA-IRRADIATIONFROM BI-212 DISTRIBUTED IN THE GROWTH-MEDIUM

It has been shown that a survival curve can be constructed from the di stribution of doses to the nuclei of cells exposed to high LET irradia tion using the variable D0 (specific lethal dose). D0 is a function of cell type and LET and exp(-D(i)/D0) is the fraction of cells which su rvive a dose D(i). The variation of D(o) with LET can be found from th e literature on track segment irradiation. Using the variation of D0 w ith LET, the survival of V79 cells irradiated by Bi-212 alpha sources was calculated by finding the probability of surviving individual pasa ges through the nuclei where the dose and LET for each passage is diff erent. The D0 obtained experimentally for V79 cells exposed to growth medium containing Bi-212 is 141 kBq.ml-1 for suspended cells and 259 k Bq.ml-1 for cell monolayers. Monte Carlo calculations give a D0 of 159 kBq.ml-1 for suspended cells and 266 kBq.ml-1 for cell monolayers.