What is X-Ray Tomography ? (CT)
X-ray computed tomography (CT) is a non-destructive technique for visualizing features within solid objects and for obtaining digital information about their geometry and 3-dimensional properties.
Synchrotron X-Ray tomography provides high-quality X-ray energy to capture the three-dimensional internal structure of real objects non-destructively and with high spatial resolution from micrometers to nanometers. This allows detailed microstructural analysis of many different materials such as small engineering components.
A CT image is often called a slice, because it corresponds to what the scanned object would look like if it were cut open along a plane. Think of it as simply as a slice from a loaf of bread, because just as a slice of bread has a thickness, a CT slice corresponds to a certain thickness of the scanned object. So, while a typical digital image is composed of pixels (pixels), CT slice images are made up of voxels (cubic points). Taking the analogy one step further, just as a loaf of bread can be reconstituted by stacking all its slices, a complete cube of an object is obtained by obtaining a single slice. Continuous CT.
The gray levels in CT slice images correspond to X-ray attenuation, which reflects the proportion of X-rays that are scattered or absorbed as they pass through each voxel. X-ray attenuation mainly depends on the properties of the X-ray energy and the density and composition of the material being imaged.
Basic principles of X-Ray Tomography (CT)
Tomographic imaging involves shining X-rays at an object from multiple directions and measuring the decrease in intensity along a series of straight lines. This reduction is characterized by Charlie's Law, which describes intensity reduction as a function of X-ray energy, path length, and material linear attenuation coefficient. A specialized algorithm is then used to reconstruct the X-ray attenuation distribution in the imaged cube.
How does X-ray computed tomography (CT) work?
The elements of X-ray tomography are the X-ray source, a series of receivers that measure X-ray intensity attenuation along multiple beam paths, and rotational geometry with respect to the object being imaged. Different configurations of these components can be used to create CT scanners optimized for imaging objects of different sizes and layouts.
The majority of CT systems use X-ray tubes, although tomography can also be performed using a synchrotron. (X-ray microscope “Synchrotron”, or gamma rays as monochromatic X-ray sources. The important tube characteristics are that depending on the target material and the maximum X-ray energy, the X-ray spectrum produced; electric current, determines X-ray intensity; and focal spot size which affects spatial resolution.
Most X-ray detectors use photomultipliers. The important parameters are the scintillator material, size and geometry, and what the photomultiplier detects and counts. In general, smaller receivers provide better image resolution, but reduce counting rates because their signal capture area is reduced compared to larger receivers. To compensate, a longer acquisition time is used to reduce noise. Common scintillation materials are Cesium iodide, gadolinium oxysulfide and sodium metatungstate.
Strength
Limitations
X-Ray Tomography (CT) has many applications in practice, in industry, medicine as well as in engineering and life sciences.
