Development and characterisation of a radiobiology proton beamline using radiochromic film dosimetry

Objective.To develop and optimise a dedicated low-energy proton beamline at the Centre for Micro-Analysis of Materials (CMAM, Madrid, Spain) for radiobiological applications.Approach.An automated irradiation system was implemented, integrating Gafchromic EBT3 radiochromic film dosimetry corrected for linear energy transfer dependent quenching and post-irradiation darkening. Dosimetric calibration was performed using multichannel analysis, and beam performance was systematically evaluated as a function of distance, raster scanning area, beam intensity and reproducibility.Main results.Optimal operating conditions were identified at moderate beam currents (⩽1 nA) and scanning areas of40×40to50×50 mm², yielding homogeneous dose distributions with reproducibility better than 8%. The dosimetric protocol demonstrated linearity across clinically relevant dose ranges and allowed a reliable correlation between irradiation parameters and absorbed dose. Proof-of-concept experiments on U-87 MG glioblastoma cells confirmed the system's ability to deliver controlled and biologically effective proton exposures, as demonstrated by clonogenic survival assays.Significance.These results establish the CMAM implantation beamline as a robust and versatile platform for preclinical proton radiobiology, providing accurate dosimetric control and supporting investigations of relative biological efficacy. The system facilitates translational advances in proton radiobiology, bridging physical and biological studies in low-energy proton irradiation.