Papers by Keyword: Digital Radiography

Abstract: The correct endodontic treatment involves the exact determination of the working length. This is accomplished by combining several techniques: the tactile technique, X-ray with the needle or the endodontic probe in the root canal and comparing with the average tooth length.The determination of average tooth length depends on the geographic area. The current table used in practice contains the values gathered on a population group that is different than ours; the table has been made on Caucasian subjects.In conclusion, our study aims to determine the proper average values of our geographic zone, the table obtained by completing the equation of the endodontic therapy that will admit the proximity of the Romanian reality.

Abstract: The paper presents foundations of the algorithm of processing primary radiographic images of large-size cargoes that allows determination of their masses. Two possible approaches to form definite algorithm of processing radiographic information were analyzed. The choice of the approaches depends on the completeness of information about the test object. The first approach to design mass determination algorithm is connected with inspecting industrial products. Industrial inspecting products are characterized by a completeness of information about the material, its structure, the geometry. The information augmented by selecting maximum X-ray energy and calibrating by test object allows determination the mass of inspecting object by the only radiographic image with high precision. The second approach is caused by indeterminacy and incomplete information about inspecting object. This case is typical for problems of cargo inspection. Corresponding algorithm modification is based on using dual-energy X-ray imaging that allows determination of the effective atomic number of test object and provision of the required precision of mass estimation.

Abstract: As known, there always exist severely degradation problems in digital radiography. How we can extract necessary textures from degraded radiographic images is the post-processing key. Local binary pattern (LBP) is a well-known method, which is widely used in fast image texture extraction. However, for noisy images, LBP can’t work well due to its sensitivity to details. On the other hand, as one of the important shock filters developed in recent years, complex shock filter possesses excellent capabilities in textural image processing. Here, by combining complex shock filter with LBP, a novel fast and efficient method, C-LBP is presented for texture extraction of degraded radiographic images. Experimental results show that comparing with traditional LBP, C-LBP not only distinguishes between noise and details in radiographic images, but also extracts image textures efficiently and rapidly, which plays an important role in developing nondestructive detection technique by low-dose ray radiography.

Abstract: Attempts have been made to develop a gray value-matching detection method for quantitative evaluation of defects and density of green parts in metal injection moulding, based on the analysis of X-ray digital radiography images. The results show that the range of gray values should be in about 1.4% when the dimensional accuracy is required within 0.3%, and voids are present where fluctuation of the gray value is larger than 10%. The quantitative evaluation of voids, powder content and density distribution through the gray value-matching can respectively predict severity of voids, shrinkage, and deformation in the sintering stage. Furthermore, the ability to detect defects and particle density distribution of this method allows for the development of an inference system to predict the optimal parameters.

Abstract: In order to improve detection efficiency of casting bolster and side frame of railway freight car, the method to automatically detect railway casting porosity and shrinkage cavity using watershed transformation based on X-ray digital radiography is presented. Firstly, while castings of a bolster and a side frame are scanned by 9Mev X-ray digital radiography system, the DR images are obtained. Then one of interested regions is selected in an image. Defects segmentation is implemented by using watershed transformation algorithm in this paper. Lastly, defects area and occupy rate are acquired by analyzing and computing, so that we can judge the casting quality. The experimental results show that defect regions and contours can be accurately acquired. This method has high robustness and practicality. It improves the efficiency of automated inspection of railway castings.

Abstract: Since Power Plant has tens of thousands welded parts in its structures, the quality on the welded parts are always a key factor for ensuring the reliability of the structures. Film based Radiography Test (hereinafter called “FRT”) is a generally accepted solution in inspecting the welded structure. However, the RT demands complex workflow, high cost, hazardous waste disposal, and etc…. In an effort to get over such shortcomings from FRT and present alternative inspection tools, this study was intended to evaluate a Digital Radiography Test (hereinafter called “DRT”). In this study, the evaluation were focused on if a DRT is applicable to the inspection of Welded structure in Power Plants, and what benefits can be generated in a use of DRT.

Abstract: Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) phosphor screen is the most popular X-ray converter in diagnostic radiology. We have investigated the fundamental imaging performance of Gd2O2S:Tb screens in terms of X-ray sensitivity and MTF (modulation-transfer function). The measurements were performed for a wide range of coverages (34 – 135 mg/cm2) by using a conventional film radiographic method. In addition, CsI:Tl having columnar structure was also investigated.

Abstract: In order to develop a cost-effective digital X-ray imaging system, we considered a CMOS (complementary metal-oxide-semiconductor) photodiode array in conjunction with a scintillation screen. Imaging performance was evaluated in terms of MTF (modulation-transfer function), NPS (noise-power spectrum) and DQE (detective quantum efficiency). The presampled MTF was measured using a slanted-slit method. The NPS was determined by 2-dimensional Fourier analysis. Both the measured MTF and NPS, and a self-developed computational model for the X-ray spectral analysis were used to determine the spatial frequency-dependent DQE. From the measured MTF, the spatial resolution was found to be about 10.5 line pairs per millimeter (lp/mm). For a 45-kVp tungsten spectrum, the measured DQE around zero spatial frequency was about 40%.

Abstract: The gas electron multiplier (GEM), placed in the drift volume of a conventional gas detector, is a conceptually simple device for producing a large gas gain by concentrating the drift electric field over a very short distance to the point that electron avalanching occurs. This device consists of a thin insulating foil of several tens of μm in thickness, covered on each side with a thin metal layer, with tiny holes, usually 100 μm or less in diameter, and with a spacing of 100-200 μm through the entire foil, perforated by using chemical etching or high-powered laser beam technique. In this study, we have investigated its operating properties with various experimental conditions and demonstrated the possibility of using this device as a digital X-ray imaging sensor, by acquiring X-ray images based upon the scintillation lights of the GEM with a standard CCD camera.