Thoracic tomography by CR: Investigation of bronchial shadows

Abstract

In cases of suspected lesions on plain radiographs such as tuberclelike shadows in the lung field, thoracic tomography has many applications for use in daily clinical practice as a follow-up step to X-ray diagnosis, with the aim of confirming the presence of such lesions or analyzing their nature in detail. Even following the appearance of CT, this modality is still significant in view of its simplicity for verification of bronchial lesions, analysis of the nature of shadows, and so on. On the other hand, the characteristics of computed radiography (CR) include: (1) images with a wide latitude by tonal conversion, (2) edge enhancement by spatial frequency enhancement, and (3) reduction of exposure dose. Thoracic tomography with CR has been used in our hospital since April 1984, leading to the conclusion that it offers many advantages, such as evaluation of both the mediastinum and lung field with one image, which is especially useful in the diagnosis of bronchial lesions. In this chapter, a comparison is made between the ability to describe normal bronchial shadows obtained in thoracic CR tomography (CRT) and those obtained in conventional film/screen tomography (CFST); the clinical usefulness was investigated using actual cases.