Monte Carlo simulation of an x-ray luminescence optical tomography scanner prototype

In this work we report the calculation of the deposited energy distribution produced by an x-ray luminescence optical tomography (XLOT) system in a phantom containing different concentrations of Gd2O2S: Eu nanoparticles. The calculations were performed via Monte Carlo simulation considering spectra from a W target x-ray tube operating between 30 and 90 kVp, with 1.0 mm Al added filtration. CT and XLOT tomographic images were reconstructed from the same data. The results show that XLOT has better detectability than CT alone, that the dose scales linearly with kVp for a fixed concentration of Gd2O2S: Eu and air-kerma rate, the scattered radiation contribution to the total dose and signal is about 20% and that the dose ratio for a 3 mm diameter insert containing 10 mg/ml Gd2O2S embedded in a 30 mm diameter water phantom is 6:1. This ratio drops to less than 2:1 for a 1 mg/ml concentration. Finally we show that the method of conjugate images can be used to correct for artifacts due to attenuation effects in XLOT images.