Tomography refers to the synthesis of sectional images or slices from external measurements of a spatially varying function.
Line integrals are the most common external measures, which are also known as projections.
Availability of multiple projections at different orientations allows accurate recovery of the originating function. Because practical implementation of tomography typically requires large amounts of data and calculations, modern computing technologies are important. CT applications are numerous and diverse. Due to its penetrating power and contrast mechanism, X-ray CT has found wide use in medical imaging, industrial nondestructive evaluation, airport screening, and microtomography. If the attenuation of the body is neglected, measures are line integrals of the source distribution.