Physics colloquium, Samuli Siltanen (University of Helsinki, Finland): "The magic of math: three-dimensional X-ray vision"

Abstract:

X-ray images were invented in the late 19th century and immediately found applications in medicine: bone fractures could be easily seen in radiographs. In the 1970’s a new X-ray based innovation was introduced. Tomography, or slice imaging, revealed the inner structure of a patient point by point as a three-dimensional map of tissues. This opened up a new world for doctors as they could do precise diagnosing based on these "CAT-scans.” Tomography is based on recording X-ray images of the patient along many directions, and then using mathematics in a clever way for combining the information into a 3D image. This talk explains that process in simple terms. An important research topic in modern mathematics is to look for a way to do tomographic imaging with the least possible amount of radiation dose to the patient. This is based on a process called regularisation, also illustrated in the talk in an easy-to-understand way. Also: there is a fun quiz revealing natural tomographers among the audience.