A method for determining the position of an array of ¹²⁵I sources based on a scintillator fiber-optic dosimeter

Abstract The aim of this study is to improve the interpolated positional accuracy of 125 I seeds in brachytherapy (BT) by combining a fiber-optic dosimeter (FOD) made up of a high-Z scintillator attached to the end of a polymer optical fiber with Monte Carlo (MC) simulation techniques. The dose detection capability of the FOD is simulated and its angular response is analyzed. A source position prediction algorithm based on the signal provided by the FOD and MC simulation is proposed by simulating the dose distribution around the 125 I source and the effect of multiple source dose superposition. This algorithm makes use of the genetic algorithm’s optimization process and fuses the output of the FOD with the a priori knowledge base to accurately predict the source position. The validation case shows that the algorithm can effectively predict the offset position of 125 I source in intertissue irradiation, which is important for improving the dose coverage accuracy and treatment effect of brachytherapy.