X-ray is a form of electromagnetic radiation that is used in medical imaging. SPEX (4 letters) is an acronym for 'Soft X-ray Emission Spectroscopy', which is a technique used to analyze the chemical composition of materials. SEEINTO (7 letters) is an acronym for 'Soft X-ray Emission Imaging and Tomography', which is a technique used to create three-dimensional images of objects. Both SPEX and SEEINTO are used to study the structure and composition of materials on the atomic level.