Extended angular response investigation of a Timepix4 silicon sensor assembly using broad X-ray spectra

Hybrid pixel detectors of the Timepix family have shown great performances for spectral and dosimetric measurements in the interventional radiology energy range. For such applications, knowledge of the angular response is essential to assess detector suitability and to establish reliable uncertainty budgets. This study presents an extended investigation of the angular response of a Timepix4 detector bonded to a 300 µm silicon sensor, measured over an angular range of −60° to + 60° in 15° steps using two reference X-ray beam qualities: RQR9 (IEC 61267) and N-20 (ISO 4037-1), covering the 10–120 keV energy range relevant to interventional radiology. Exploiting the spectroscopic capabilities of the detector, the angular response was characterised in 2 keV energy bins, enabling energy-resolved analysis for the first time using realistic broad X-ray spectra. For the RQR9 beam quality (20–120 keV), the total fluence ratio remains within 2 % of unity across all tested angles, demonstrating a flat angular response over this range. For the N-20 beam quality (10–18.6 keV), a cosine-shaped dependence is observed, with fluence decreasing by up to 30 % at 60°, consistent with the photon mean free path becoming comparable to the sensor thickness at these energies. These results confirm that Timepix4 silicon sensor assemblies are well suited for dosimetric and spectroscopic applications in interventional radiology and support its use for ambient dose equivalent measurements in this energy range. The angular response data reported here provide a robust basis for uncertainty budgets on Timepix measurements across a broad range of practical applications.