[Experimental and clinical studies on utility of advanced multiple-beam equalization radiography for the diagnosis of pulmonary mass lesions].

The thorax has a wide dynamic range from low (lung fields) to high X-ray absorption (mediastinum, retrocardiac and retrodiaphragmatic areas). The conventional screen/film system cannot visualize each area of the thorax with good contrast on a single sheet of film with the wide latitude. To solve this problem, advanced multiple-beam equalization radiography (AMBER), a type of scanning equalization radiography, has been developed. The present studies were designed to evaluate the usefulness of AMBER for the chest from the experimental and clinical aspects. In the experimental study, an imaging technology assessment of density and contrast properties and a phantom study for detecting a simulated pulmonary nodule were carried out. In the clinical study, visualization of the normal structures and abnormal shadows in chest radiographs was assessed. X-ray findings in the AMBER films were compared with those of conventional chest radiographs using the screen/film system. In the analysis of density and contrast properties, AMBER showed more favorable contrast properties than the conventional system, regardless of background density. In the phantom study, the detectability of the nodule in the retrocardiac or retrodiaphragmatic region in an AMBER film was superior to that of the conventional system, and there was no reduction in detectability in other regions of the peripheral lung field. In the clinical assessment, AMBER was excellent for visualization of the mediastinum and the normal structures and lesions in the retrocardiac and retrodiaphragmatic areas. AMBER can be concluded to be excellent in visualizing not only the high absorption area, which is difficult to observe with the conventional system, but also the low absorption area.