Um acelerador linear compacto para a produção de radioisótopos de tomografia por emissão de pósitrons (PET): estudos preliminares

Abstract

A compact linear accelerator will be designed for the local production of Positron Emission Tomography (PET) radioisotopes in the forthcoming Brazilian Maximum Biological Containment Laboratory (LNMCB), a biosafety level 4 (BSL-4) laboratory under construction inside the campus of the Brazilian Center for Research in Energy and Materials (CNPEM). The local production is vital to allow the use of short halflife PET radioisotopes, such as 11C (20.4 min), 13N (10 min), 15O (2 min) and 18F (110 min), for the study of highly dangerous pathogens in small animals using a hybrid PET/MR imaging system. The accelerator is under development within the framework of a collaboration agreement with the European Organization for Nuclear Research (CERN), which suggests a solution based on an innovative and very compact linear accelerator known as High Frequency Radio-Frequency Quadrupole (HF-RFQ). This solution presents several technological challenges and demands high specialized human resources, which is ideal for a frontier scientific center as CNPEM. This thesis documents part of the first efforts to understand not only theoretical and practical aspects of an HF-RFQ, but also the specific demands of the application for which the accelerator is being designed, the production of short half-life PET radioisotopes. The main routes of production of the desired radioisotopes were identified and their cross-sections curves were analysed in order to decided the most proper bombarding ion and the best output energy range for the accelerator. It was concluded by this preliminary analysis that protons accelerated up to an energy range of around 7 and 8 MeV could properly produce the short half-life PET isotopes 11C, 13N, 15O and 18F. Also, a bibliographic review of all the four existing HF-RFQ projects is presented for the purpose of gathering useful material that will help CNPEM engineers to learn from what other research groups around the world are developing.