Pilot study of a postal dosimetric audit for radiotherapy in reference conditions
DOI:
https://doi.org/10.37004/sefm/2022.23.1.002Keywords:
postal audit, dosimetry, quality assurance, OSL, radiotherapyAbstract
In 2019 a pilot study for postal dosimetry audits in radiotherapy centers was performed by the “Centro Nacional de Dosimetría”. The audit consisted in a verification of the calibration of megavoltage photon beams in reference conditions, for which optically stimulated luminescence (OSL) dosimeters placed in a water phantom were used. Forty-eight radiation beams were audited, with energies: 6, 10 and 15 MV with flattening filter and 6 and 10 MV flattening filter free (FFF). A difference between the declared absorbed dose and the measured dose below 5% was considered acceptable.
The mean difference between the declared and measured doses was 0.8%, ranging from −0.9% to +1.9%. The uncertainty in the dose measurement was 1.6% (k = 1). No results above the acceptance limit were observed.
From this study it is concluded that the proposed method to audit radiotherapy photon beams is viable and the results obtained for the different audited centers are below the acceptance limit. The uncertainty in the determination of the absorbed dose is similar to that of other organizations that offer this service.
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