Precession measurement of perturbed angular correlation in double-photon emission nuclides with magnetic field for novel RI imaging method

Abstract

Nuclear medical imaging techniques such as single-photon emission computed tomography and positron emission tomography, are important and sensitive diagnostic methods in the field of medicine. These techniques are used to measure and visualize the accumulation of radiolabeled molecules using gamma rays. In a previous study, we investigated a novel method, double-photon emission imaging, by utilizing cascade nuclides with cascade gamma rays. This method helps extract information regarding the local microenvironment, such as pH and chemical state, around a nucleus through the time–space correlation of emitted gamma rays (Shimazoe et al., 2022). In this study, we used a magnetic field as the external field for inducing Larmor precession by the magnetic field and characterized the effect in a liquid-state cascade radioisotope. We designed eight GAGG-MPPC 8 × 8 (512 channels in total) array detectors using an individual time-over-threshold readout system to form a ring and characterize the angular correlation of the direction of gamma-ray emission of an aqueous solution of 111In caused by the magnetic field. The impact of the existence and strength of the magnetic field (from 0 to 3T) on the angular correlation were measured and characterized. A method for estimating the location of the source was discussed using the fact that information on the strength of the magnetic field applied to the source can be calculated from the gamma radiation readings.