Quantitative Cerenkov luminescence imaging: Measurements and simulations

Cerenkov luminescence imaging (CLI) is an optical imaging modality recently proposed to image β emitting radionuclides through the Cerenkov light they produce in tissue. CLI has been suggested in particular for β
^-
emitting isotopes, which are difficult to study by other means, and as a cost-effective alternative to PET, yet with reduced penetration depth and spatial resolution. In this work we tested the predictive capabilities of a Monte Carlo model developed within the Geant4 platform for the description of a CLI experiment. Our final goal is to use Monte Carlo simulations to quantitatively correlate the number of detected Cerenkov photons with the radionuclide distribution. The code could be used also as a tool for experiment planning, for example in evaluating CLI applications. To test the reliability of the Monte Carlo predictions, CLI measurements were performed with a simple geometry that can be easily simulated (a radionuclide diluted in water) and the CLI signal measured with an electron multiplying charge coupled device (EMCCD) was compared with the Monte Carlo prediction. We observed that, below a certain detection limit and for particular acquisition settings, the measured signal depended on the acquisition settings. Apart from these exceptions, the simulated CLI signal was systematically 0.8 times the measured one. This small and constant offset suggests that the code could have good predictive capabilities in water.