Provided is a diagnostic method and system capable of applying tomography to industrial long cylindrical process systems, such as a pipe line, which are difficult to diagnose using existing medical or industrial computed tomography (CT) scanners. Existing industrial X-ray CT scanners cannot be used for such a pipe that is attached to the process system and thus cannot be placed on the turntable, and existing image diagnostic apparatuses of a fan beam type, a collimated beam type, etc. having a stereotyped structure are next to impossible to move and use for undetachable process systems and their peripheral devices. To solve these problems, there is provided a gamma-ray tomography scanning system that is capable of being directly attached to a pipe in operation and measuring a cross section of the pipe.
