| Abstract [eng] |
In developed countries more than 20 % [1] of all radiation exposure can be attributed to the medical field. All medical applications require some type procedures that guarantee their quality control. This is very important because any errors or miscalculations can lead to negative effect to patient health. Dosimetric measurements are a part of quality control measures. In-vivo dosimetry using thermoluminescent dosimeters is preferred in this practice, due to the broad availability of detector materials and variety of detector size and shape. High measurement uncertainties is the main disadvantage of this method. This problem in personal dosimetry is being solved applying different calibration and uncertainty evaluation methodologies, but radiotherapy field still lacks this kind of practice. In this work uncertainty assessment methodologies for both systematic and random uncertainty values evaluation were applied for medical practise and used for low energy radiotherapy. It was found that after exposure to 2 Gy of dose TLDs measured doses from 1,6 GY to 2,26 Gy, variations in results being from -14% to +20,7%. Using of correct uncertainty estimation methodology expanded uncertainty of TLD measurements can be reduced by ~20-21% with the result reproducibility of ~ 88% for dose range of 2-4 Gy. After comparison of doses measured by TLDs and by GafChromic films it was found, that in the case of low scattering, dose measurement errors were lower than 10 %. |
