UDC 53.087.44
OPTIMIZING THE TECHNIQUE FOR IN-VIVO ABSORBED DOSE RATE MEASUREMENT USING SMALL-SIZED SCINTILLATION DETECTORS
I. N. Abalakin, post-graduate student, NRNU «MEPHI», Moscow, Russia;
orcid.org/0000-0003-0703-5719, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
V. T. Samosadny, Dr. Sc. (Tech.), full professor, NRNU «MEPHI», Moscow, Russia;
orcid.org/0000-0003-0321-8120, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
A. M. Medvedkov, head specialist, NIITFA, Moscow, Russia;
orcid.org/0000-0003-2085-4890, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
A. V. Sumin, head of project office 6, NIITFA, Moscow, Russia;
orcid.org/0000-0002-9065-1610, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
The main task of this paper is evaluating the factors that impact scintillation detector signal, and compensating these factors influence measuring the characteristics of dose field in clinical practice. The design of the detector under test makes it possible to estimate the contribution of stem effect, as well as to calculate correction factor for this effect to be considered in useful signal. Due to the peculiarities of in-vivo measurements, temperature dependence of detector components and angular anisotropy of sensitivity require special attention. In addition, radiation damage leads to gradual degradation of the signal, which must also be taken into account in the algorithm of measured value calculation. The aim of this work is to increase the accuracy of absorbed dose rate measurement using small-sized scintillation detectors during contact radiotherapy procedures up to 2,5 %.
Key words: in-vivo dosimetry, scintillation detectors, gamma-therapeutic complex AGAT-VT, Vavilov-Cherenkov effect, 3D dose field analyzer, signal temperature dependence, sensitivity angular anisotropy, PSD radiation degradation.