ESTRO 2022 - Abstract Book

S99

Abstract book

ESTRO 2022

Purpose or Objective To characterize the response of small active detectors - suitable for measurements in a water phantom - in terms of energy and angular dependence at low energy X-ray beams and give recommendations for their use in electronic BrachyTherapy (eBT) dosimetry. Materials and Methods Three active small detectors, Exradin A26 chamber, IBA RAZOR Nano chamber, and PTW 60019 microDiamond were calibrated in terms of air kerma using the N (ISO 4037-1) and TW (DIN 6809-4) X-ray calibration series from 7.5 kV to 100 kV. The responses to mono-energetic photons and their uncertainties were determined using Bayesian parameter estimation, assuming a thin plate spline parametrized model. The angular dependence of the three detectors was also measured in air in a 180° range using the Zeiss INTRABEAM system (50 kV). For both, energy and angular response, the detectors were in parallel orientation. Results The air kerma response functions for the three detectors are shown in Figure 1. The approach followed improves on the traditional procedure of associating the response to the mean energy of the corresponding spectra since it is consistent with 18 calibration qualities simultaneously. The in-air measured angular response of the detectors is shown in Figure 2, note that charge readings were normalized to the parallel incidence (0°).

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