MODELING OF CONTINUOUS LOW-DOSE RATE AND ACCELERATED FRACTIONATED HIGH-DOSE-RATE IRRADIATION TREATMENTS IN A HUMAN GLIOMA CELL-LINE

The Incomplete-Repair model of Thames in its original and in its two-r epair processes forms is used to analyse continuous and fractionated i rradiation of a glioma cell line treated in vitro. Furthermore, the In complete-Repair model is rederived based on the linear-quadratic model bearing a cubic term. Our results show a potentially enhanced but non significantly improved fit to the data when comparing the cubic to the original form of this model. The repair halftime values showed a decr ease, followed by an increase, as a function of small doses (<1.5 Gy) per fraction. This is observed using both the original and the cubic f orms of the model. We propose this behaviour to be due to an induced r esistance of the repair system followed by a saturation process. Two-r epair processes were not seen directly due to the large scatter in the fast and the slow components of repair. Repair half-time values are e stimated for various dose per fraction protocols using the original an d extended forms of the Incomplete-Repair model. Two-repair processes that are consistent as a function of dose per fraction were not detect able in a glioma cell line treated in vitro.