Использование явления термостимулированной радиационно- обусловленной люминесценции микрокристаллов морской соли для внутриполостной «ин виво» дозиметрии при брахитерапии рака предстательной железы источником Ir192: оценка потенциала

Abstract

Aim of the study – use of the phenomenon of thermo stimulated luminescence in natural microcrystals of sea salt (NaCl) in the range of therapeutic doses in order to develop a method for off line intracavitary «in vivo» dosimetry of patients at high dose-rate brachytherapy of prostate cancer with a 192Ir source. Samples of aliquots with natural microcrystals (a fraction with a size of about 100 m) of sea salt were used in the study. Measurements were carried out using a Harshaw 3500 device, which is a thermoluminescent reader. Irradiation of samples to construct the calibration dependences was carried out by a standard 90Sr/90Y source providing the dose rate of 2.99 mGy/s. It was established, that: (1) there is a linear dose dependence of luminescence intensity from studied microcrystals in the range of therapeutic absorbed doses from 1 to 20 Gy with an error in measuring the luminescence intensity of the studied microcrystal samples of less than 5%; (2) it was revealed that fading (decrease in microdosimeter readings over time) does not exceed 5% 5 days after irradiation; (3) clinical testing of «in vivo» dosimetry method using sea salt microcrystals for high dose-rate brachytherapy of prostate cancer shows that the results of measurements of absorbed doses in the organ at risk (rectum) using studied natural NaCl crystals are consistent, within the limits of error, with the results of measurements by synthetic LiF:Mg,Ti crystals (with intracavitary placement in the organ at risk and simultaneous irradiation both assemblies of these microcrystals). It was concluded that the use of the studied sea salt microcrystals is promising for «in vivo» dosimetry in application to 192Ir high dose-rate brachytherapy of prostate cancer.