Calibration of the LNMRI Secondary Standard Ionization Chamber for 131I capsules used in nuclear medicine

• Published in: Journal of radioanalytical and nuclear chemistry 2012-07, Vol.293 (1), p.211-216
• Main Authors: Chaves, Tainá Olivieri, Iwahara, Akira, Tauhata, Luiz, Rezende, Eduarda Alexandre, Correia, Amanda Ribeiro, de Oliveira, Estela Maria
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Diagnostic Radiology; Hadrons; Heavy Ions; Inorganic Chemistry; Nuclear Chemistry; Nuclear Physics; Physical Chemistry
• ISSN: 0236-5731; 1588-2780
• DOI: 10.1007/s10967-012-1660-y

The radionuclide 131 I has been increasingly used in nuclear medicine therapy procedures. Nowadays, the 131 I source administered to the patient is manufactured in two different geometries: solution and capsules. The purpose of this study is the accurate measurement of the activity present in a 131 I capsule without destroys it. The methodology to determine the capsules activity is to obtain the calibration factor of an IG12 secondary standard activity measurement system based on the IG12 well-type ionization chamber set up at Brazilian national metrology laboratory for ionizing radiation (LNMRI) of institute of radiation protection and dosimetry (IRD).The result obtained, 6.4670 ± 0.0381 × 10 −18  A Bq −1 , is quite similar to the calibration factor of the 131 I solution contained in the standard ampoule geometry, 6.4515 ± 0.0368 × 10 −18  A Bq −1 . After obtaining the calibration factor it was used to measure 131 I therapy capsules in order to check the performance of radionuclide calibrators of some Brazilian nuclear medicine centers.