TECHNOLOGYComputed Tomography (CT) technology, or CAT scan, has been an important tool in medicine for many years. The value of CT comes from it's powerful imaging capabilities. This imaging has provided medical professionals with a much better understanding of the physical conditions of their patients. Inversa System Ltd's exclusive Backscatter Computed Tomography (BCT) technology brings the power of CT technology to industry. BCT adds another tool to the repertoire of NDT, enabling inspection through intermediaries such as insulation and cladding, while the plant is still in operation. The Problem:Traditional radiography imaging requires access to two opposite sides of an object. One-side inspection is currently possible with ultrasonic reflection, however ultrasonic waves are easily dispersed by interfaces, and require the inspected plant to be stripped of insulation and temporarily decommissioned. One-sided imaging applied to the interrogation of extended objects (e.g., aircraft structure) and thick formations (e.g., concrete walls) can be conducted with radiation scattering but its use has been hindered by the nonlinearity of the image reconstruction problem. The Reason:The nonlinearity is caused by the intensity of scattered radiation increasing with the density of the scattering point, but decreasing with the density of surrounding points, due to the attenuation of radiation before and after scattering. The nonlinearity of the scattering problem is a challenge in image reconstruction, as it leads to instability in the iterative process necessary for finding a solution to the problem. A possible way of overcoming this difficulty is to limit the solution to the low-density domain, or restrict the total distance of travel to less than the equivalent of one mean-free-path (mfp) of the incident radiation (i.e., about 0.5 mfp thickness for one-side imaging). However, this depth limitation has made backscatter tomography impractical for heavy industry. Inversa System Ltd's Solution:Developed from years of research, Inversa System Ltd's proprietary process Backscatter Computed Tomography (BCT) product overcomes the problems with traditional inspection methods and is suitable for diverse industrial usage. BCT technology will make deep inspection of dense materials in heavy industry possible for the first time and without major disruption or shutdown. The test object shown below illustrates the capabilities of BCT, in its early stages. The test object, a fire clay brick, was scanned from the side. However, the image reconstructed using Inversa System Ltd’s process gives a top view of the object as if a virtual core sample from an object was taken.
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