What is Tomography?
Tomography imaging is the process where image slices of the object of interest are taken. These slices can then be reconstructed to produce a full image representing the original object. Computer Tomography (CT) is a widely used imaging service which has been in used for medical purposes since the early 1970s.
Industrial Process Tomography (IPT) is the equivalent imaging process used in a wide variety of industrial applications. Instead of being used to look inside the human body, IPT can be used to look inside industrial processes. IPT is a relatively new process, and currently still in an early stage of development. It does however offer many important solutions for the monitoring of industrial processes in a non-destructive and non invasive manner, allowing for the monitoring of chemical processes, improving product yield and quality.
There are three basic elements for tomography :
1. A number of fixed sourced or a mobile source surrounding the targeted object;
2. A number of fixed detectors or a mobile detector surrounding the targeted object;
3. Reconstruction of the image through PC reconstruction algorithms.
There are 2 broad types of tomography, ‘hard field’ and ‘soft field’.
Hard Field Tomography
Hard field simply means that regardless of the type of material or medium, the direction of travel of the energy waves from the power source is constant. Examples of Hard Field Tomography are X-ray micro-tomography (XMT), Magnetic Resonance Imaging (MRI) and Positron emission tomography (PET).
Soft Field Tomography
Electric current is introduced to the medium being imaged and the electric field distribution is determined by the physical electrical properties of that material, allowing a map of resistance, capacitance or impedance to be reconstructed by a computer to form the tomogram. The nature of soft field is much more complex than hard field, and requires considerably more computer analysis and algorithms to reconstruct the image. Examples of Soft Field Tomography are Electrical Resistance Tomography (ERT), Electrical Capacitance Tomography (ECT) and Electrical Impedance Tomography (EIT).