Performance evaluation of alpha-particle discrimination using ultra-thin plastic scintillation sheets and their application to alpha-emitters for targeted alpha therapy.

Alpha-particle discrimination using ultra-thin plastic scintillator sheets for measuring the activity of α-emitters under the existence of α- and β-emitters was investigated. Am, P and Ra were also used to evaluate the applicability of the present technique to α-emitters for medicine, and the self-absorption effect due to additives was investigated for validation. The results demonstrated that ≥95% of detection efficiency for α-particles emitted from Am with ≤1% β-contribution of P for the low carrier salt concentration solution. Regarding using Ra, ≥90% of α-efficiency was achievable with ≤1% β-contribution through sufficient dilution and selection of scintillator sheets of appropriate thicknesses.