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Computed Tomography (CT) has witnessed remarkable advancements in the last decade, particularly in the reduction of X-ray exposure, while maintaining high-quality images. A novel concept that enhances contrast-to-noise ratio substitutes the anti-scatter grid with a photon filtering method based on time of flight (ToF). The ToF-CT detector design includes an array of small, optically isolated scintillator crystals, each connected to an independent photosensor, to measure the ToF information of individual X-ray photons. However, the interaction of photons produced by an X-ray with a scintillator crystal can result in the emission of visible light beyond the crystal boundaries, leading to signal contamination and reduced performance through inter-crystal crosstalk. As the crystals become narrower for better spatial resolution, the probability of optical crosstalk is expected to increase. To assess the impact of inter-crystal crosstalk on the sensitivity and spatial resolution of ToF-CT detectors, we conducted a Monte Carlo simulation of scintillation events in the detector and evaluated several crosstalk metrics for various configurations of LYSO crystals connected to SiPM arrays. For a spherical collimated source located in the middle of a central scintillation detector measuring 1x1x2.5 mm3 and a lower energy threshold of 20 keV, the probability of optical crosstalk for one X-ray was found to be 0.12%. These findings indicate that ignoring crosstalk signals can reduce tomograph sensitivity using these detectors, along with a 7% decrease in energy resolution.