Monte Carlo-based dosimetric comparison of indigenous and commercial ¹⁰⁶Ru/¹⁰⁶Rh eye plaques using a mathematical eye phantom

This study evaluates and compares the dosimetric performance of the Bhabha Atomic Research Centre (BARC)¹⁰⁶Ru/¹⁰⁶Rh eye plaques and a commercially available similar BEBIG CCA eye plaque using Monte Carlo simulations via the FLUKA code. Simulations were performed in both spherical water and mathematical eye phantoms to determine dosimetric parameters such as reference absorbed dose rates, percentage depth doses, off-axis dose profiles, and 2D dose mappings. The on-axis reference absorbed dose rates at 1 mm depth in the mathematical eye phantom was calculated as 10.712 ± 0.003 mGy/min-MBq for the BEBIG CCA plaque and 10.194 ± 0.003 mGy/min-MBq for the BARC plaque, showing close agreement between the two applicators. Off-axis and depth dose distributions confirmed that the BARC plaque delivers comparable dose profiles to the BEBIG plaque, with all critical eye structure doses, including the lens, retina, and cornea, well within established tolerance limits. The similarity in dose distributions between water and mathematical phantoms suggests that water can serve as a practical approximation for dosimetry evaluations. This study demonstrates that the BARC plaque provides dosimetric characteristics comparable to the BEBIG plaque, support its potential use in clinical ophthalmic brachytherapy.