Production of 99Mo and 64Cu in a mixed field of photons and neutrons in a clinical electron linear accelerator

Abstract

The medical isotopes 99Mo and 64Cu were produced via the dual routes of 100Mo(γ,n)99Mo + 98Mo(n,γ)99Mo and 65Cu(γ,n) 64Cu + 63Cu(n,γ)64Cu reactions from natMo and natCu targets via irradiation with bremsstrahlung + neutrons field using a 15MV clinical electron linear accelerator (linac). The activities of 99Mo and 64Cu measured by off-line γ-ray spectrometry were 1.05 and 13.5 Bq per gram of natMo and natCu per gray-second irradiation. Fluka calculations estimate 28.77 ± 5.5 and 33.35 ± 6.33% contribution to 99Mo and 64Cu yield, respectively due to the secondary co-produced neutrons by (γ,n) reactions in the linac head. The 64Cu yield is observed to increase up to 46% after moderation of the neutrons with varying thickness of a solid water phantom. This study suggests the possibility of irradiating natural targets of Mo and Cu in an electron linac to produce 99Mo and 64Cu as a cost saving measure for medical applications.