[Evaluation of FCR (Fuji Computed Radiography) images applied to standard radiography for the diagnosis of chest diseases].

FCR (Fuji Computed Radiography) was added to plain chest radiography in order to evaluate its image characteristics and to determine the best image characteristics and to determine the best image processing program by comparing the visibility of shadows on conventional X-rays and on six FCR hard copy images processed by six mutually different image processing program. FCR showed excellent ability to visualize abnormal lung shadows as well as normal chest structures when processed by a moderate spatial frequency enhancement (spatial frequency 0.11 cycle/mm, level of enhancement). FCR also proved superior to the conventional film-screen system in the visualization of hilar and mediastinal structure as well as lung shadows. The effects of the image processing program on the visibility of shadow, granular and linear shadows were clearly demonstrated when a more intense spatial frequency enhancement (spatial frequency 0.18 cycle/mm, level of enhancement) was performed. The same results were obtained in terms of reticular and linear shadows and calcified lesions. On the contrary, low density shadows with poorly defined margins the lung field and infiltrates from mycoplasma pneumonia were well depicted by a program with a slightly steeper gradation (gamma; 1.0) and minimal frequency enhancement. Accordingly, FCR was found to be useful for the screening of abnormal chest X-ray shadows whereas it was also likely to demonstrate the best image when processed by the most appropriate image processing programs, depending on the characteristics of the shadows.