The study was conducted to calibrate and characterise the response of the Timepix3 photon-counting hybrid pixel detector. The study was conducted to calibrate and characterise the response of the Timepix3 photon-counting hybrid pixel detector. The goal was also to determine the impact of the angular variation of the detector to the source, of temperature change, and of ambient or strobe light on the on the detector response (measured fluence and energy spectrum). The impacts were studied using X-ray fluorescence lines, as well as Am-241 and Fe-55 radioactive sources. Angular variation measurements indicated angular dependence. This dependency increased with the angle and increased with lower energies. A decrease in fluence of up to 98.4% was recorded for Fe-55 (5.89 keV) and 43.1% for Am-241 (59.56 keV) at an angle of 90 degrees. Temperature measurements showed a 4% decrease of photon count when increasing the temperature from 10 degrees C to 36 degrees C. Energy spectra were shifted to lower energies when the temperature increased. Measurements with variable light intensities showed no variations in terms of fluence or energy spectra. However, if it was a strobe light, the fluence was overestimated by 10% and the spectral shape presented an additional artefactual peak around 3 keV. To restrict the variability of the detector response and avoid a time-consuming calculation of the error factor, due to the detector's temperature variation, we showed that it is necessary to keep the measurement temperature as close as possible to the temperature at which the calibration was performed. We also discovered the necessity of focusing on other relevant parameters such as the effect of the ambient light level or the angle of incidence of the X-ray beam impinging the detector on the detector response. This enabled us to propose a set of correction factors that can be used for other applications.