Reconstruction is the mathematical process by which the displayed image is produced from the raw data.
Used equipment and data processing methods to reconstruct CT images:
See also Zoom Reconstruction, Reconstruction Matrix and Multiplanar Reconstruction.

Back projection is a mathematical procedure used to reconstruct CT images. Back Projection is based on the blurring of the x-rays within a projection back along the direction in which they were measured.

Decontamination is a process to reduce or remove unwanted material, such as radioactive, toxic chemical or biological substances. Decontamination from the surface of an object or from an area applies to removal by washing, biological agents, chemical action, mechanical cleaning, or other techniques.

Gamma radiation is electromagnetic radiation emitted in decay of radionuclides. Also called gamma ray and sometimes shortened to gamma (e.g., gamma-emitting radionuclides).

Fissile isotopes such as 233U, 235U or 239Pu get exposed to a thermal neutron beam. The resulting nuclear chain reaction is controlled by moderators such as graphite, Beryllium or heavy water.
For example Mo-99, source for Tc-99m, is produced by fission of highly enriched uranium (HEU) in a few reactors around the world (monitored and controlled by The International Atomic Energy Agency).