Purpose: To compare the difference in relative biological effectiveness (RBE) between (10)B ions and a (60)Co gamma-ray beam for human melanoma cells using in vitro cell survival based on a clonogenic assay.
Materials and methods: Cells were irradiated in vitro under aerobic conditions with (60)Co and (10)B ions with different linear energy transfer (LET) (40, 80 and 160 eV nm(-1)). The dose to the cells was determined using ferrous sulphate dosimetry and an ionisation chamber. The standard linear-quadratic model and the newly proposed repairable conditionally repairable damage (RCR) model were used to calculate the RBE.
Results: The RBE at 10% cell survival for 40, 80 and 160 eV nm(-1) boron ions compared with (60)Co were 1.98 (1.83-2.22), 2.85 (2.64-3.11) and 3.37 (3.17-3.58), respectively, of almost independence of the model used in the calculation.
Conclusions: Different cell survival models may generate different RBE, especially at low doses and high cell survival levels.