Development and evaluation of a standard for absorbed dose to water from alpha-particle-emitting radionuclides

Abstract Targeted radionuclide therapy (TRT) and brachytherapy with alpha particles has gained significant clinical relevance recently. Absorbed dose traceability to a standard is currently lacking in the dosimetry chain. The short range of water <100 μm complicates absorbed measurements form attenuation perturbation effects. aim this work was develop validate for from alpha-particle-emitting radionuclides. A dosimetric formalism realize surface per unit activity using windowless cylindrical parallel-plate ion chamber (IC) introduced. IC-based Monte Carlo (MC)-based correction factors were calculated planar circular 210 Po alpha-particle emitter. measured air compared MC-calculated dose. IC nominal 4 mm collector diameter composed polystyrene-equivalent material utilized as standard. MC simulations performed TOPAS code finite source size, backscatter, emission angle divergence by modeling source. Multiple measurement trials measure ionization current at gaps 0.3-0.525 range. proposed employed calculate point-like recombination polarity be <0.50% when 150 V/mm electric field strength applied. agreed within 2.05%. size backscatter corrections <10% being 93-239% 2.8913×10 -6 Gy s -1 Bq combined uncertainty 4.23% k=1. This demonstrated ability