Comparison of the relative biological effectiveness of neutron irradiation of different energies on melanoma cells.

PURPOSE: Understanding the energy-dependent variation in relative biological effectiveness (RBE) is crucial for both neutron radioprotection and therapeutic applications. This study aims to evaluate the biological impact of neutron irradiation on A375 human melanoma cells using neutron beams of different energy ranges, with the goal of contributing to the optimization of radioprotection standards and the advancement of neutron-based cancer therapies, such as Boron Neutron Capture Therapy (BNCT).

MATERIAL AND

METHODS

A375 human melanoma cells were irradiated using two distinct neutron beams: one in the keV range at the CNA facility in Sevilla, and another in the MeV range at the CIEMAT facility in Madrid. Clonogenic assays were performed to evaluate cellular response and determine RBE values. The biological effects were assessed and compared with previously obtained data from thermal-equivalent neutron energies and reference photon irradiation.

RESULTS

The MeV-range neutron beam induced slightly stronger biological effects than the keV-range beam, but the observed RBE difference was notably smaller than the ∼50% gap predicted by ICRP models. Instead, the experimental trend closely aligned with previous theoretical RBE estimations based on secondary particle contributions. These results underscore the need to reevaluate current radioprotection weighting factors and support the refinement of neutron-based therapeutic protocols.