A Model for estimating dose-rate effects on cell-killing of human melanoma after boron neutron capture therapy

Matsuya, Yusuke  ; Fukunaga, Hisanori*; Omura, Motoko*; Date, Hiroyuki*

When delivering a high absorbed dose to cancer cells following boron neutron capture therapy (BNCT), heterogeneous dose distribution, the time line of B concentrations and the long dose-delivery time must be considered. Changes in radiosensitivity during such a long dose-delivery time can reduce the probability of tumor control; however, such change has not yet been evaluated. Here, we developed a cell-killing model that accounts for changes in microdosimetric quantities and dose rates depending on the B concentration and investigated dose-rate effects (cell recovery during BNCT irradiation) of melanoma. The developed model shows good agreement with in-vitro experimental survival data for exposure to Co -rays, thermal neutrons, and BNCT. The model estimation suggests that the impact of cell recovery during BNCT irradiations with high linear energy transfer (LET) is reduced compared to Co -rays irradiation with low LET. The present model is expected to predict radio-sensitivity for BNCT irradiations.