A novel method to assess crosstalk in single-grain luminescence detection

Luminescence imaging with an EMCCD camera is an innovative approach to single-grain luminescence detection. In theory, it allows for the random placement of grains on a disc, but in practice, attributing photons to specific grains remains unachievable. Currently, single-grain discs with fixed grain placement are primarily used, though these are still susceptible to crosstalk, e.g. overlapping of luminescence signals from adjacent grains. A standardized method for identifying, correcting, or eliminating crosstalk is not yet available. In this paper, we introduce Moran's I, a measure of spatial autocorrelation, as a novel method for assessing crosstalk in single-grain luminescence detection. Using simulations with induced crosstalk, we demonstrate that Moran's I can effectively detect crosstalk when interpreted within the context of its pseudo-p value. These results are corroborated by those obtained on a measured luminescence dataset for which crosstalk is deliberately enhanced by increasing the region of interest (ROI) selected for luminescence signal integration. These results on simulated and measured data show that Moran's I can be used to select optimal ROI diameter to enhance signals whilst limiting crosstalk. Finally, we examined the effect of modelled crosstalk on three types of equivalent-dose distributions, finding that normal distributions are unaffected by crosstalk, whereas bimodal distributions became mixed, and the shape of skewed distributions alters. These results have implications for ROI selection for well-bleached, mixed and heterogeneously bleached sediments.