A set of electrolyte capacitors were inspected using x-ray micro-computed tomography (μ-CT) system developed at the Department of Physics Gadjah Mada University, Indonesia. Testing was done for three electrolyte capacitors. The one is in good condition and the other two are considered broken. Those were broken due to either high voltage operation or leakage of the tube. Under customized μ-CT inspection, 3-D presentations of the objects have been developed. The results showed that the image profiles, radiation attenuation profiles and linear attenuation coefficient distribution on top, middle and bottom area were able to determine the aluminum plate and electrolyte papers. Good electrolyte capacitor has higher radiation attenuation and nearly uniform across the core of the capacitor. This is in contrast with the broken capacitors.
Essentially, 3D computed tomography (CT) image should be obtained from huge data (raysum) set from multiple views and multiple projections. Due to mechanical limitation, a compromise between fast scanning process and quick data sampling has to be considered. This paper presents our approach on performing the fast scanning process and quick data sampling in order to obtained good CT image with acceptable criteria. A set of nice results were presented.
A model for 3D image reconstruction of x-ray micro-computed tomography scanner (micro-CTScan) has been developed. A small object has been put under inspection on an x-ray micro-CTScan. The object cross-section was assumed on the x-y plane, while its height was along the z-axis. Using a radiography plane detector, a set of digital radiographs represents multiple angle of views from 0º to 360º with an interval of 1º was obtained. Then, a set of crosssectional tomography, slice by slice was reconstructed. At the end, all image slices were stacked together sequentially to obtain a 3D image model of the object being inspected. From this development, lessons on the way to have better understanding on the internal structure of the object can be approached based on the cross-sectional image slice by slice and surface skin.
A method for sinogram data interpolation based on a sinusoidal pattern in computed tomography has been developed. Sampled sinograms were acquired based on angular interval scanning of 5o, 10o, and 20o. Then each resulted sinogram was interpolated following sinusoidal pattern to make a complete full scanning sinogram as if they were sampled at 1o. After that, a formal summation convolved filtered back projection was applied to each sinogram to yield a crosssectional image. This method was successfully interpolated limited number of projections data to obtained complete sinogram. It works for simple and homogenous object. However, for high variation of physical properties, e.g. linear attenuation coefficient values, this method needs more consideration on interpolation strategies to produce good image.
A quality performance indicator for digital x-ray micro-radiography system has been developed. It was used for nondestructive testing on microstructure object. A set of testing apparatus for image quality indicator (IQI) was developed from acrylic sheets that were cut carefully using laser cutting tool. These IQI apparatus imitated common standard such as step wedges, holes indicator, and lines/wires tester. The IQI step wedge was used to measure the relative x-ray penetration capability. The IQI holes indicator was used to measure the Modulation Transfer Function (MTF) of the imaging system and the IQI lines/wires tester was used for pixel calibration and image spatial resolution determination. From this experience, this simple, low cost, customized, quick made and accurate IQI set fulfilled the performance testing requirement procedure.
An x-ray micro-digital radiography (μ-DR) system has been developed at the Gadjah Mada University Indonesia. The μ- DR system was developed as an add-on unit on an x-ray Diffraction (XRD) system using one extra beam-port as its radiation source. A fluorescence screen encapsulated in a dark tube then coupled by a CCD camera was used as an imaging plate. The radiography objects were some sample clays for earthen or ceramic material of handicraft. The clays differ by particle size, namely: 40 mesh, 60 mesh, 80 mesh, and 100 mesh. The objects were put in front of the imaging plate and then they were exposed by x-ray beam. The image formed on the screen was captured by the CCD camera and then it was converted into digital microradiograph of a size of 720x576. Then, after noise suppression process and normalization procedure, the microradiograph were compared each other by considering particle size. This facility can be used as a non-destructive and testing material studies for examining the quality of earthen or ceramic handicraft.
A research on application computed tomography to quality inspection of brass alloy has been done. The aim of the research was to study the capability of computed tomography system with source radiation isotope I-131 in order to mapping different quality of any type of brass alloy and study on the influence of activity of isotope I131 to the reconstructed image has been done. The inspection has been done by scanning three type of brass alloy, and comparing to the metal Cu and Zn which are the fundamental substances of brass alloy. The quality of brass alloy was identified through the profile of absorption of radiation and the distribution value of linear coefficient attenuation (μ) on the image and image contrast. The influence of activity isotope I-131 was studied by performance through the sinogram and reconstructed image. The result showed that the good quality of brass alloy have highest absorption of radiation than the bad quality of brass alloy, which were represented by the higher value of μ. From the visual observation on the
reconstructed image, it showed that the higher activity of isotope I-131 would be used on the scanning process, the sharper sinogram contrast and reconstructed image contrast.
The comparative study on the image quality between Computed Radiography (CR) and digitized film radiograph has been carried out. We have successfully digitized a radiographic film of an aluminum step wedge, an ASTM and coins using a flatbed scanner. Then, a comparative study was developed using CR as a reference. We used 4 set-up variations of kV and mA. The image quality was assessed based on the visual analysis: brightness, sharpness, and contrast, and the
physical information analysis. The results show that visually the image quality of CR was better to the digitized film radiographs. However, CR was unable to distinguish the physical information such as the effect of voltage or current and the object characteristic to the image quality.
A computed tomography (CT) apparatus using laser beam and photodiode is currently developed for faulty detection in transparent materials such as diamonds and crystals. Faults in diamond and crystals are hard to be detected using visual inspection. A unique and artistic feature may appear on the surface due to internal cracks or anomalies. While those are hard to be distinguished, the unique feature appeared may be more precious compare to any perfect objects. A simulation study for understanding the physics behind the phenomena has been performed. This has been followed by set-up of mechanical and sensor system along with the electronics readings. Previous results on individual testing show that we may develop a pretty optical CT system that can be used for fault detection in any transparent materials.