[en] Dual energy x-ray radiography can be used to separate soft and dense-material images for medical and industrial applications. It can be performed successfully with a line-scanning system because of its scatter-free nature. With area detectors, however, scattered radiation also contributes to the signal. This undesired behavior of scattered x-ray photons in radiography causes serious degradation of contrast in observed images, and poor separation of soft- and dense-material images. The percentage of scattered photons is typically 60 % to 70 % in the lungs and 80 % to 95 % in the mediastinum for a standard PA chest radiograph. Even though anti-scatter grids can reduce the scatter fractions to 20 % to 30 % in the lungs and 40 % to 60 % in the mediastinum, dual-energy radiography requires additional scatter correction. Several methods for scatter correction have been suggested to improve results. Such methods, however, require additional lead blocks or detectors, and additional exposures to estimate the scatter fraction for every correction. Others have used only one or two convolution kernels, even though the scatter point spread functions have different shapes as a function of object thickness. A new scatter correction method in dual-energy radiography called the TB scatter correction method is suggested by this study, based on iterative thickness estimation using unique scatter point spread functions. The TB correction method uses information from a dual-energy algorithm to correct the images. In order to verify the effectiveness of this method, a set of MCNP simulation and experiment was performed. The scatter information for each combination of thickness of two materials, aluminum-water phantom in simulation and aluminum-acryl phantom in experiment, was represented in the form of a scatter point spread function. Scatter point spread functions can be either simulated, or measured and induced by Fourier transform. The way to measure the scatter point spread function is also proposed, and it may give the great possibility for various other applications to the TB correction method. In TB correction, based on the uncorrected signals, the thickness of each material is calculated by a conventional dual-energy algorithm. The scatter information of corresponding thickness from the database of the scatter spread function is then used to correct the original signals. For the aluminum-water simulation, the iteration of TB scatter correction reduced the relative-thickness error from 32 % to 3.4 % in aluminum, and from 41 % to 2.8 % in water. As the experimental verification using aluminum and acryl, the TB correction method reduced the relative errors by 50 % to 5 %. The suggested TB scatter correction method has several merits over conventional methods. It does not use any additional hardware or exposure, and has better performance than others because of nearly exact correction in spatial distribution of scatter signals using material and thickness-dependent unique scatter point spread functions. One drawback of the proposed approach arises from a characteristic of the scatter point spread function. Scatter point spread functions with several different orders of object materials or with a different thickness of air gap may have different shapes and magnitudes. In contrast with CT, dual-energy radiography does not specify the arrangement of the material (i.e., which material is located on the top and which is on the bottom) These effects were not taken into account in this study, since preliminary simulation results indicated that these differences were insignificant in the range of interest for this study. And moreover, an idea for the modified TB correction method is suggested in this study for the application to chest radiography. Overall, the TB correction method considerably improved the dual-energy imaging. The TB scatter correction method can be applied to two-material dual-energy radiography such as mammography, contrast imaging, and industrial inspections. As additional application examples of dual-energy radiography, two works are also presented in this study. Preliminary experiments have been performed for detection of organic materials focusing on organic material detection by different high-energy detectors, which are use CsI and CWO as a scintillator. Organic and inorganic materials were successfully separated in a thin objects range. Generally, plastic explosives contain a high concentration of organic material, especially nitrogen and oxygen, and have a higher density than other organic materials. Using these characteristics, the organic material detection capability of a dual-energy method can be applied to an inspection system with simple modification of conventional systems. Volume estimation of solitary pulmonary nodules in chest radiography using dual-energy algorithm is suggested as the second application. Successful elimination of rib shadows with tissue-selective imaging and volume estimation of nodule with background rejection were performed. This method gave an accurate estimation of isolated solitary pulmonary nodules from the lung boundary, but with some errors for overlapping with the lung boundary. This estimation method, based on dual-energy subtraction, could be applied to detection and measurement of lung nodules in chest radiographic CAD. Even though those works do not use scatter correction method, further research may show other applications for the dual-energy scatter correction method