Monte Carlo characterization of 169Yb as a high-dose-rate source for brachytherapy application by FLUKA code

Higher initial dose rate and simplifying HDR room treatment of 169Yb element among other brachytherapy sources has led to investigating its feasibility as high-dose-rate seed. In this work, Monte Carlo calculation was performed to obtain dosimetric parameters of 169Yb, Model M42 source at different radial distances according to AAPM TG-43U1 and HEBD Report about HDR sources in both air vacuum and spherical homogeneous water phantom. The deposited energy resulted by FLUKA as Monte Carlo code using binning estimators around 169Yb source was converted into radial dose rate distribution in polar coordinates surrounding the brachytherapy source. The results indicate a dose rate constant of 1.14 ± 0.04 cGy.h(-1).U(-1) with approximate uncertainty of 0.04%, air kerma strength, 1.082± 2.6E-06 U.mCi(-1) and anisotropy function ranging from 0.386 to 1.00 for radial distances of 0.5-10 cm and polar angles of 0°-180°. Overall, FLUKA dosimetric outputs were benchmarked with those published by Cazeca et al. via MCNP5 as one of validate dosimetry datasets related to 169Yb HDR source. As a result, it seems that FLUKA code can be applicable as a valuable tool to Monte Carlo evaluation of novel HDR brachytherapy sources.