As explained in Section 2.6.2, the uncertainties associated to the diffusion effects could be neglected. As for the calibration flasks, the combined uncertainty on the optical attenuation coefficients along the profile measurements took into account the uncertainties associated to the flask repositioning, the correction for spontaneous oxidation, the reading temperature variation and the post-irradiation waiting time. It consisted in subtracting the mean optical attenuation coefficient of a ROI at the center of an unirradiated flask to the optical attenuation coefficients of the irradiated flasks corresponding to the time between the acquisition of the reference and data scans of each irradiated flask.īased on these uncertainties, the linear fits, applied to the data to establish the calibration curves, provided the uncertainties associated to the fit parameters, a λ and b λ. ![]() As the spontaneous oxidation was found linear with time and reproducible for non-irradiated gel flasks of a same batch, a correction of this effect was applied to the data. The combined uncertainty on the optical attenuation took into account the uncertainties associated to the flask repositioning between the acquisition of the reference and data scans, the ROI at the center of each calibration flask for Δ μ determination, a reading temperature variation of ± 0.1☌ and a post-irradiation waiting time between 20 min and 50 min. ![]() ![]() For every gel flask used to establish the calibration curves at 590 nm and 633 nm, the standard uncertainty on the dose D delivered under the TRS 398 reference conditions with the Truebeam accelerator, u ( D ) stand, was given by 0.47 %.
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