Selection of key parameters for the high yield production of 99mTc via 100Mo (p, 2n) 99mTc reaction in a cyclotron

Abstract

The most common radioisotope in nuclear medicine imaging is ^99mTc. One of the efficient ways to alleviate the instability of the ^99mTc supply chain in recent years is to produce ^99mTc by ¹⁰⁰Mo (p,2n) in a cyclotron. The selection of key parameters in production is crucial for enhancing resource utilization and productivity. The purpose of this study is to examine how specific factors, such as the target parameters (material type, size) and irradiation parameters (proton energy, beam spot size, beam intensity, irradiation time, and cooling time) impact the yield of ^99mTc, to obtain the appropriate technological parameters for producing ^99mTc via ¹⁰⁰Mo (p,2n) ^99mTc in a cyclotron. The ^99mTc yields of enriched targets (¹⁰⁰Mo-1, ¹⁰⁰Mo-2, ¹⁰⁰MoO₃, ¹⁰⁰Mo₂C) and natural targets (Mo-nat, MoO₃-nat) under various irradiation conditions are simulated by using the Monte Carlo software FLUKA, and the obtained results are analyzed and compared. The findings indicate that for enriched targets, the optimal beam energies for maximizing ^99mTc yield is approximately 17.3 MeV, while for natural targets, it is around 13 MeV for a high RNP of ^99mTc. Enriched ¹⁰⁰Mo metal demonstrated superior production capacity, followed by molybdenum carbide to molybdenum oxide, natural molybdenum is not recommended for production but can be used as a test material. Shorter irradiation and cooling periods are preferable. A beam radius that is marginally smaller than the target radius is ideal. The target thickness should be maintained to reduce the incident energy to the reaction threshold. The optimal production parameters corresponding to the specified targets are obtained in this work, which provides valuable guidance for selecting key parameters in the preparation of ^99mTc using a proton accelerator.