For questions related to radon transform. It's an integral transform whose inverse is used to reconstruct images from medical CT scans.
Radon transform is the integral transform which takes a function $f$ defined on the plane to a function $Rf$ defined on the (two-dimensional) space of lines in the plane, whose value at a particular line is equal to the line integral of the function over that line. The Radon transform is widely applicable to tomography, the creation of an image from the projection data associated with cross-sectional scans of an object.