Estimation of Uncertainty in Measurements of Dosimetric Characteristics of Photon Fields Generated by Linear Electron Accelerators

he article considers the main components of the uncertainty budget when measuring
the average ambient dose equivalent rate H*(10) (or ADE for short) generated by a medical linear electron accelerator (or LINAC for short). The budget of the ADE uncertainty is made for the case of assessment of the performance of dosimetric equipment in the fields of pulsed microsecond photon radiation generated by LINAC according to the method described in [1,2,3,4]. The estimation of the ADE uncertainty generated by LINAC at the measurement point was performed according to the procedure described in GOST 34100.3.2-2017 [5]. According to this scheme, at the first stage the determination of the basic dosimetric quantity – kerma rate in air (or kerma rate for short), generated by LINAC at a given point, was performed by using the reference dosimeter DKS AT5350/1 in combination with the ionization chamber TM32002. At the second stage, the kerma rate was converted to the ADE using the conversion coefficient according to STB ISO 4037-3-2022 [6]. The uncertainty estimation after each stage was based on the explicit form of the expression linking the input and output parameters (current – kerma rate for the first stage, kerma rate – ADE for the second stage). It was found that the uncertainty of the ADE generated by the LINAC at the measurement point, calculated according to the above described scheme, does not exceed 13% for all operating modes of the LINAC.