A method, an apparatus and a system are provided for deriving a characteristic of a product using X-rays. X-ray image data associated with the product is received, the X-ray image data being derived by performing an X-ray scan of the product using an X-ray imaging apparatus and conveying attenuation information resulting from interaction of X-rays with the product. A response of a reference product to X-rays is then simulated to generate simulated X-ray image data. The simulated X-ray image data and the received X-ray image data are then processed to derive one or more characteristics of the product. Information conveying the derived characteristic of the product is then released. In a specific implementation, the product is a liquid product comprised of a bottle at least partially filled with liquid and the derived characteristic of the liquid product is a threat status assessment associated with the liquid in the bottle. In another aspect, a simulation engine for simulating interactions between X-rays and objects is also provided.