Radiobiological studies on the 62 MeV therapeutic proton beam at lns catania: I. survival of HTB140 melanoma cells

The aim of this study was to determine the initial inactivation of cells induced by high-energy proton beam designed for the treatment of eye melanoma. Exponentially growing HTB140 cells were exposed to an unmodulated 62 MeV proton beam delivered over the single dose range from 8 Gy to 24 Gy. Position of samples was in the zone of the Bragg peak, having high LET values. Surviving fractions were evaluated at 6, 24 and 48 h post-irradiation. The survival curves exhibited a well-known shoulder, decreasing for doses higher than 8 Gy. Therefore, a significant dose dependent early cell inactivation after single delivery of 16 Gy to 24 Gy to the cell monolayer was observed. With the increase of the post-irradiation incubation time, a better killing effect, as the consequence of clonogenic survival, was detected.