Director of Medical Imaging Professor Guang-Zhong Yang speaks to Reuters in front of a video of robotic surgery on a lung at Imperial College London October 24, 2008. A mechanical snake that can perform operations through the mouth or rectum is just one of the futuristic devices researchers believe will transform traditional surgical techniques. Picture taken October 24, 2008. To match feature HEALTH-ROBOTS/ REUTERS/Luke MacGregor (BRITAIN)