Analysis of IAEA thermoluminiscent and radiophotoluminiscent postal dose audit of teleradiotherapy equipment performed in Russia over the past 20 years

The article addresses results of IAEA thermoluminescent (TL) and radio-photoluminescent (RPL) postal dose audit of the external beam radiotherapy (EBRT) equipment, linacs and cobalt units, performed in Russia over the past 20 years between 1999 and 2019. The aim of the work was to evaluate results of IAEA dose audit: to compare the dose determined at the IAEA Dosimetry Laboratory with the dose stated by the Russian participant. The acceptable deviation between the doses is ≤5%. In the first-time audit 817 dosimeter sets were used, 430 of them were irradiated with 60Co of EBRT machines and 387 sets were irradiated with bremsstrahlung radiation of various energies. To search factors that affected the clinical dosimetry quality 133 beams, mainly 60Co gamma-ray beams, were retested. Over the twenty-year period a total of 9% of bremsstrahlung beams and 27% of gamma-ray beams exceeded the 5% tolerance interval. The observed deviation may be resulted from the use of outdated radiotherapy equipment, lack of trained workers with high-level experience and competence in medical radiology, medical physics, IT, as well as lack of appropriate dosimetry systems. The common reason of observed dosimetry audit outcomes may be the result of inconsistency between irradiation geometry calculated with the use of treatment planning system and the true irradiation geometry, as well as errors of calculation. Having assessed the worksheets we have found many partially completed sheets, information on irradiation conditions and dose calculation process was unavailable or incorrect, all mentioned made it difficult to analyze causes of observed deviations. Nonetheless, we witness a positive trend in the dose audit outcomes, at the same time, the amount of errors in Russian worksheets is still larger than in other countries-participants of the IAEA/WHO audit. It is possible to improve the radiation therapy quality and to increase radiotherapy benefits and effectiveness due to expanding the practice of autonomous auditors at the Federal and regional levels, as well as organizing of specialists’ on-site visits to Radiotherapy Centers. Taking such actions makes it possible avoidance of communication problems and increase in the detection rate of true causes of observed shortcomings in clinical dosimetry quality.