Determination of operational quantities Hp(0.07) and Hp(3) for an indigenously developed ¹⁰⁶Ru/¹⁰⁶Rh source for beta...

The ¹⁰⁶Ru/¹⁰⁶Rh radionuclide is extensively utilized in nuclear science, radiation therapy, and industrial applications due to its unique properties. This beta-gamma emitter, derived from spent nuclear fuel, exhibits a mean beta energy of 1.43 MeV and a maximum beta energy of 3.54MeV, making it ideal for various therapeutic interventions while minimizing damage to surrounding tissues. Its significance extends beyond medicine, being recommended by the International Organization for Standardization (ISO) as a calibration source for radiation dosimeters. The latest ISO revision underscores its use in generating reference beta-particle radiation fields, both with and without beam-flattening filters, facilitating accurate dose measurements and calibration standards. In India, the Bhabha Atomic Research Centre (BARC) has pioneered the incorporation of indigenously developed ¹⁰⁶Ru/¹⁰⁶Rh source for personnel monitoring. Using an extrapolation chamber as the primary standard, operational quantities Hp(0.07) and Hp(3) were determined at source-to-chamber distances of 11cm, 20 cm, and 30cm, both with and without a Mylar beam-flattening filter, while implementing all newly introduced ISO 6980-2, 2023, correction factors. Measurements showed that at 11 cm, the inclusion of a flattening filter produced a ∼4% increase in Hp(0.07), attributed-via simulation-to additional low-energy electrons generated in the filter. At 30cm, TLD-based evaluations confirmed beam uniformity within ±5% over a 15-cm² area when the flattening filter was used. Comprehensive characterization of the source, updated dosimetry following revised ISO protocols, and confirmation of beam uniformity support the inclusion of the ¹⁰⁶Ru/¹⁰⁶Rh source in the Beta Secondary Standard (BSS-2) system.