Investigation of the response variability of ionization chambers for the standard transfer of SIR-Spheres

Cheick Thiam (1) , Christophe Bobin (1) , Valérie Lourenço (1) , Vanessa Chisté (1) , Marie-Noëlle Amiot (1) , Xavier Mougeot (1) , Didier Lacour (1) , Fabrice Rigoulay (1) , Laurent Ferreux (1)

1 LNHB - Laboratoire National Henri Becquerel

The present paper addresses the calibration of well-type ionization chambers (ICs) used at LNE-LNHB as standard transfer instruments to calibrate hospitals in the case of $^{90}$Y-labelled resin microspheres SIR-Spheres (Sirtex, Australia). Developed for interventional oncology, this radiopharmaceutical is directly injected in the liver for cancer treatment by radioembolization also known as selective internal radiation therapy. The present work was carried out in the framework of the European project MetroMRT (Metrology for molecular radiation therapy). As commonly performed in radionuclide metrology for radiopharmaceuticals, the objective is to ensure the metrological traceability of SIR-Spheres to nuclear medicine services. The first studies were focused on primary measurements of SIR-Spheres based on the Triple to Double Coincidence Ratio method (using both liquid scintillation and Cerenkov counting), applied after the chemical dissolution of the $^{90}$Y-labelled resin microspheres. Because $^{90}$Y is a high-energy $\beta^-$-emitter, the IC response strongly depends on the transport of electrons in the radioactive solution and the surroundings (vial, chamber liners and materials). The variability of IC-responses due to the geometry dependence is investigated by means of measurements and Monte Carlo simulations (Geant4 code) in the case of a Vinten IC. The aim of the present study was also to propose a reliable uncertainty for IC calibration for the standard transfer of SIR-Spheres to end-users.

Keywords: $^{90}$Y; MICROSPHERES; metrology; ionizing radiations; SIR-Spheres® standardization; Radionuclide metrology; Radionuclide Calibrator; Nuclear-Medicine; Ionization chamber calibration; SIR-Spheres standardization; Monte Carlo simulation; $^{90}$Y-labelled resin microspheres; Calibration of ionization chambers; Simulation Method

Domains: Nuclear Experiment [nucl-ex]; Medical Physics [physics.med-ph]; Nuclear medicine; Pharmaceutical sciences; Modeling and Simulation

Cheick Thiam, Christophe Bobin, Valérie Lourenço, Vanessa Chisté, Marie-Noëlle Amiot, et al.. Investigation of the response variability of ionization chambers for the standard transfer of SIR-Spheres. 20th International Conference on Radionuclide Metrology and its Applications, ICRM2015, TU – Vienna University of Technology; BOKU – University of Natural Resources and Life Sciences, Vienn; BEV – Federal Office of Metrology and Surveying, Jun 2015, Vienne, Austria. Paper number RMLS-0-142. ⟨cea-02477222⟩