X-rays were first discovered in 1895 by the German physicist Wilhelm Röntgen and are used in medical imaging to evaluate bone fractures. Occasionally, X-rays are unable to identify microfractures in the bone. Therefore if nanoparticles are incorporated with hafnium, they have been shown to attach to microcracks in the bone and allow X-rays to form a coloured image using computed technology developed by MARS. This spectral computed tomography (CT) imaging with hafnium produces high resolution coloured images at the location of the microcracks in the bone. The hafnium composition makes it detectable to X-rays which generate a signal that can be used to image the cracks. Also, this technique can be used to determine if any blockages are present in the heart. Conventional CT does not have a soft-tissue contrast compared to spectral CT. When X-rays pass through the body, they become attenuated and produce radiographs at various intensity levels. A Medipix3 detector can measure the energy of the X-ray attenuation. All materials can attenuate at different wavelengths due to the atomic structure of the material involved. For example, the bone is made mostly from calcium and is able to attenuate the X-rays which appear white on the radiographs. Also, when using the contrast agent iodine, the attenuated X-rays will appear white. However, by using the MARS CT scanner, it is possible to differentiate between the density and atomic variation of the material. The density is a function of the brightness of the image and the atomic structure determines the colour.