Séminaires LLR

XEMIS: low dose 3γ medical imaging with a single-phase liquid xenon Compton camera

by Lucia Gallego Manzano (Subatech)

Seminar room (LLR)

Seminar room


The XEMIS (XEnon Medical Imaging System) program developed at Subatech laboratory proposes a low dose functional medical imaging technique based on the detection in coincidence of 3γ rays. This innovative imaging modality aims to directly reconstruct the position of each disintegration of a specific (β+,γ) radioisotope: the Sc-44, using for the first time a liquid xenon (LXe) camera. The benefit of this technique is expressed directly in a large reduction in the dose injected to the patient and/or the exam time. A preliminary R&D program has been successfully completed with a small dimensions LXe time projection chamber (TPC), called XEMIS1, that holds 30 kg of xenon with a drift length of 12 cm. The results obtained from a detailed study of the detector response have provided the experimental evidence of the feasibility of the 3γ imaging technique. Based on the good results obtained with XEMIS1, a larger-scale prototype for small animal imaging is now under construction. XEMIS2 is a single-phase cylindrical LXe TPC with 200 kg of xenon (active mass 70 kg) and a total drift length of 24 cm. The particular geometry of XEMIS2 was specifically designed to provide a full coverage of the small animal allowing the detection of the 3γ rays with a high sensitivity thanks to a large axial field of view. Moreover, since XEMIS2 has been designed for preclinical applications in hospital centers, a compact and completely safe cryogenic infrastructure called ReStoX (Recovery and Storage of Xenon) has been developed and successfully installed at Subatech. The XEMIS2 camera will be operational and available from 2017 for preclinical research at the Center for Applied Multimodal Imaging (CIMA) located in the Nantes Hospital. In this talk I will give an overview of the XEMIS project. I will present and discuss the latest results obtained with XEMIS1 and in particular, I will be focused in the ionization signal produced after the interaction of an ionizing particle with the LXe. Further, I will introduce the new prototype XEMIS2 and I will show that the expected results are compatible with the necessary requirements for small animal imaging with a liquid xenon Compton camera, and very promising for the future of the 3 imaging technique.