Modeling rhenium-186 and rhenium-188 distribution in a neutron-activated rhenium wire and effect of the distribution on beta dosimetry in a water phantom

Radioactive β-emitting rhenium wire brachytherapy sources produced by neutron activation in an isotropic thermal neutron field have a non-uniform radial radioisotope distribution. We modeled this distribution and confirmed the model by experimental measurements on wires of 0.1–1.0 mm diameter. When the corrected radial distributions of 186Re and 188Re were used, the calculated dose distribution around a 0.5-mm wire agreed with the distribution measured with Gafchromic film in a solid water phantom to within 5.0% over the therapeutic range (radius of 0.4–2.8 mm).