Speakers
Description
Ensuring international metrological traceability for Air Kerma-Area Product (PKA) measurements is crucial for modern clinical dosimetry. Traditional calibration methods have limitations in geometry, uncertainty, and clinical deployment. This study proposes a hybrid methodology to establish a robust traceability chain for PKA meters. To develop and validate a computational protocol for the PKA calibration chain, integrating high-resolution spectrometry and Monte Carlo (MC) simulations to reduce systematic uncertainties and provide a validated model for calibration audits. A hybrid approach was implemented in three stages: (1) An experimental cascade substitution calibration chain (reference chamber → Patient Dose Calibrator (PDC) → clinical PKA meter). (2) Precise characterization of X-ray spectra (RQR3-RQR10) using a CdTe detector and correction algorithms. (3) Faithful modeling of the experimental setups in TOPAS MC code, using the measured spectra as input to independently calculate calibration coefficients (N_K). The results were cross-validated. The PDC was validated as a transfer standard with an expanded uncertainty (k=2) of ~3%. Excellent agreement was observed between measured and simulated spectra. The direct comparison of calibration coefficients for the clinical meter (e.g., RQR8 quality) showed a difference of <3% between experimental (N_K=1.02 ± 3.0%) and MC (N_K=1.05 ± 1.5%) methods, within experimental uncertainties. The integration of MC simulations validated by CdTe spectrometry proved to be a powerful tool for metrological auditing, systematic uncertainty reduction, and protocol optimization. This framework provides a robust, exportable model for metrology laboratories, promoting the international harmonization of PKA dosimetry practices.