At first glance this appears to be one of those annoying posters where you have to "unfocus your eyes" to see the image that, along with halogen lamps and the Spin Doctors, is one of the bits of detritus by which many of us remember the nineties. But no! It's actually the CT scan of a human skull afflicted with a cancerous thyroid. Radiologist Kai-hung Fung transforms the CT scans he takes into works of art; you can see more here.