Speaker
Description
The gamma-MRI approach proposes to use spin-aligned long-lived nuclear states and to combine the detection of their asymmetric gamma-ray emission with spin manipulation as in Magnetic Resonance Imaging (MRI). It aims to pave the way to a new medical imaging modality capable of overcoming some of the limitations of existing imaging modalities (PET, SPECT, MRI): the low spatial resolution of the nuclear medicine imaging techniques and the low sensitivity of the MRI.
Gamma-MRI is an ambitious and multidisciplinary endeavor requiring a multistep approach. Here, we report about its first milestone and proof-of-concept experiments, namely the production and detection of spin-aligned long-lived nuclear states.
The necessary experimental setup was assembled, commissioned, and tested with radioactive metastable Xe (mXe) isotopes in the summer of 2019 in the chemistry laboratories at ISOLDE.
The selected radioactive isotopes - $^{129m}Xe$ ($t_{1/2} = 9$ days, $E_γ = 197$ keV, $I = 11/2^{-}$) and $^{131m}Xe$ ($t_{1/2} = 12$ days, $E_γ = 164$ keV, $I = 11/2^{-}$) - were produced at the nuclear reactor in Grenoble (ILL), transferred to MEDICIS, where the samples were decontaminated in order to reassure the chemical cleanliness of the Xe samples, and then used experimentally for performing the proof-of-principle experiments. The feasibility of radioactive Xe isotopes production was also tested at ISOLDE at the GLM beamline ($^{133m}Xe$; $t_{1/2} = 2.19$ days, $E_γ =233$ keV, $I = 11/2^{-}$) in the summer of 2018.
Preliminary data analysis hints at modest, but clear, gamma-emission asymmetry, which proves the build-up of nuclear-spin alignment of metastable Xe. Further analysis and in-depth interpretation of the results is ongoing, taking into account different scenarios of nuclear-sublevel occupations, and supported by computational simulations.
This talk aims to cover the progress that has been made so far in the project.