RQR beam qualities measurement with the Timepix4 detector

This work presents, to the best of the authors’ knowledge, the first attempt at reconstructing X-ray spectra with a hybrid pixel detector for radiation protection applications in the scattered field around fluoroscopy devices. The performance of the Timepix4 detector was evaluated under reference conditions using RQR beam qualities. A dedicated methodology was developed to correct for detection efficiency, explicitly accounting for contributions from Compton scattering and the photoelectric effect. Accuracy was assessed through Monte Carlo simulations and comparisons with published RQR reference spectra. In addition, particle fluence measurements obtained with Timepix4 were validated against values derived from kerma factors and ionisation chamber measurements performed in a calibration laboratory. The results show excellent agreement between reconstructed and reference spectra up to 70keV, with residuals below 1.7% and relative photon fluence shifts within 5%. At higher energies, discrepancies increase due to the low detection efficiency of the silicon sensor, requiring large correction factors and leading to greater statistical fluctuations. Nevertheless, the system demonstrated acceptable performance up to 120keV, with fluence shifts remaining below 16%. Linearity was confirmed across all beam qualities and intensities investigated, consistent with previous studies on earlier Timepix ASIC generations. Overall, these findings demonstrate that Timepix4 can provide reliable spectral and fluence measurements in reference X-ray beams, offering valuable information for radiation protection studies in scattered fields where conventional detectors are of limited use. Future improvements in readout bandwidth and spectral deconvolution methods are expected to extend its applicability to higher energies and clinical environments. •Spectral measurements were taken in reference conditions with Timepix4.•Results show strong agreement with published reference spectra.•Consistent results in terms of particle fluence were found up to 120 keV.•Timepix4 shows great potential for spectral measurements in interventional radiology.