Present state and future prospect of neutron tomography

As to the neutron tomography (NCT) in Japan, the results of researches began to be reported around 1980. At present, there are more than 50 reports in Japan and abroad. In this report, the outline of NCT and the present state of its research in Japan are described, and the problems and the future form of NCT technology are discussed. As the method of NCT, the photographing of a series of one-dimensional images, logarithmic conversion, the making of sinograms, and restructuring computation are carried out. There are more than ten algorithms for the restructuring, such as filter correction back projection process and Fourier transformation. The main results of the researches on NCT in Japanese universities and Japan Atomic Energy Research Institute are reported. NCT is at research stage, and for putting it to practical use, there are a number of physical limitations. It is difficult to obtain the portable neutron sources with sufficient strength. Also often the time for acquiring images is limited. In the case of NCT, the elimination of scattered beam is difficult, and the photographing system with excellent gradation resolution has not yet been obtained. As to the general discussion on the present state and problems of NCT, it is expected to make explanation in the periodical ''Hibaku Kensa (Nondestructive Inspection)''. (K.I.)