Comparison of radiation effects of gadolinium and boron neutron capture reactions.

PURPOSE

Cell survival assays were performed to evaluate the effects of radiations released during neutron capture reactions by gadolinium-157, boron-10 and by the combination of both.

MATERIALS AND METHODS

Single cell suspensions with or without Gd-157 and/or B-10 were exposed to thermal neutrons produced by the Kyoto University reactor, and standard cell survival curves were obtained.

RESULTS

Under the same molarity, cytocidal effects were 1.5 times greater for Gd-157 than for boron when compared at 10% survival levels. The presence of B-10 enhanced the radiation effect of Gd-157 neutron capture by 1.2-fold, suggesting that cells were not sufficiently irradiated as a result of neutron fluency attenuation by the presence of excess neutron capture agents in the medium.

CONCLUSIONS

When an equal number of atoms were present, Gd-157 was effective as B-10 when exposed to an equal number of thermal neutrons. However, there was no benefit observed in the combination of Gd-157 and B-10 for neutron capture therapy. Further studies are needed to determine optimal Gd-157 and B-10 concentrations as a function of tumor dimension.