Determination of correction factors and correction coefficients for calculations of the absorbed dose

The need to control the dose received by a patient during radiation therapy (RT) is dictated by the quality assurance requirements, which encompass a broad system of organizational and technical measures aimed at achieving consistency and precision in dosimetry measurements. The ultimate goal of using a quality assurance system in RT is to ensure high accuracy in delivering the dose to the tumour, reducing the irradiation volumes of normal, healthy tissues and organs near the target (tumour lesion). It has been established that to enhance the effectiveness of radiation treatment and to reduce the number of complications in subsequent periods, it is necessary to irradiate the local target in the patient’s body with a dose error no greater than ±5%. To control the calculation of the absorbed dose in water using thermoluminescent (TL) dosimeters, irradiated on a gamma therapeutic device for remote radiation therapy, it is necessary to study the influence of various factors (fading, non-linearity of indications, energy dependence, reproduction of the TL signal, presence of a holder) on the magnitude of the TL signal. We have studied and identified various corrective factors and their error values that may affect the calibration of the system (TLD-100 powder (Rexon), thermoluminescent reader PCL-3). In determining the corrective factors to account for the daily drift of the PCL-3 device, the TL signal obtained during the exposure was adjusted based on the control powder indicators. As a control powder, TLD-100 (Rexon) was used, irradiated with an absorbed dose of 2 Gy under standard conditions and aged four months to obtain a stable TL signal.