Development Of Target System For Medical Isotope Tc-99m Production Based On The Superconducting Linac

^99mTc is currently one of the most widely used medical isotopes in the world.It is typically used in Single Photon Emission Computed Tomography（SPECT）after pharmaceutical processing.In China,the supply of ^99mTc mainly relies on imports.Lanzhou University and the Institute of Modern Physics（IMP）of the Chinese Academy of Science have launched a collaboration to research and develop the ^99mTc production solution based on the 25 Me V superconducting proton linac,so as to mitigate the pressure of medical isotope supplies and alleviate China’s dependence on medical isotope imports.This thesis elaborates the research and development of the high-power target system,which meets the requirement of 24 Me V@500μA proton beam impinging highly-enriched ¹⁰⁰Mo target continuously for 6 hours.The target system consists of three subsystems:（1）vacuum system,（2）target body and cooling system and（3）driving and auto-control system.After theoretical analysis and experimental verifications,each subsystem and the whole system meet the design requirements.The conclusions are as follows:（1）The leak rate of the vacuum chamber is less than 1×10^-12 mbar·L/s in the atmosphere and the ultimate pressure is less than 1×10^-6 Pa,which are both lower than the design parameters;（2）The target and cooling system meets the heat dissipation requirement given 6-h irradiation of the 12-k W proton beam;（3）The driving and auto-control system can realize the function of remote control and ensure the stable operation of the target system in a high-level radiation field.High-power proton beam bombardment of a ¹⁰⁰Mo target body would produce a high-level radiation field.Based on the parameters of the beam,this work utilizes FLUKA to perform shielding assessment of the target system and the experimental terminal.The conclusions are as follows:In each stage of the irradiation,the internal and external dose rates of the terminal are lower than the regulated limit,the key electrical actuators can be effectively protected.The target system finally passed the quality acceptance check after the on-site test.This work accumulates experience for the subsequent development of high-power target systems for accelerator-based large-scale medical isotopes production.