Deposition of Ag125I on silver substrates for fabrication of radioactive seed for brachytherapy

• Grant number: 12/01312-3
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): April 01, 2012
• Effective date (End): December 31, 2013
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal Investigator: Koiti Araki
• Grantee: Roberta Mansini Cardoso
• Home Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The low cost production of radioactive seeds is urgently demanded by the Brazilian government to enable the treatment of localized cancer by thePublic Health System (SUS). The process for deposition of radioactive iodine on silver wire segments (based on the exchange of chloride by iodide used asa radioactive source) has been developed in the 1970s. Nevertheless allattempts in reproducing it were unsuccessful particularly due to two problems:low reproducibility and low efficiency. Thus, in this project we aim the understanding and control of the AgCl deposition and chloride exchange processes to produce AgI films, as well as the development of alternative deposition methods to generate thin homogeneous, adherent and stable films of Ag125I on small pieces of silver wire that will be used for the manufacture ofradioactive seeds for treatment of localized cancer. In this case, direct AgI deposition methods on pieces of silver wire, ideally leading to 100% deposition efficiency of radioactive iodine, will be pursued. In addition, themethod should be simple, cheap and fast allowing the deposition of homogeneous AgI films exhibiting suitable radioactivity (about 800 mCi) in some hour instead of tens of hour. Those characterists are essential to make the large scale production of radioactive seeds for brachytherapy (batches of tens to hundreds of units) economically viable to meet the demands of the Brazilian Public Health System.The source of radioactive material is a solution of iodate/iodide obtained by disproportionation of 125I2 in a sodium hydroxide solution(commercially available as a solution of radioactive sodium iodide). This project will be carried out in collaboration with Dr. Mary Elisa Martins Chuery Rostelato Darwish and the doctoral student Carla de Souza responsible for the development of the national project for production of radioactive seeds forbrachytherapy at IPEN.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

CARDOSO, ROBERTA MANSINI; DE SOUZA, CARLA DARUICH; CHUERY MARTINS ROSTELATO, MARIA ELISA; ARAKI, KOITI. Highly efficient method for production of radioactive silver seed cores for brachytherapy. Applied Radiation and Isotopes, v. 120, p. 76-81, FEB 2017. Web of Science Citations: 0.