[Radiological assessment of pulmonary function by computed radiography with imaging plates]

The usefulness of computed radiography with imaging plates (CR) for radiological assessment of pulmonary function was studied. Visibility of intrathoracic structures on CR images was compared with that on screen-film images. Intrathoracic structures included right intermediate arterial trunk, midzonal vessels, peripheral zonal vessels, the trachea at the level of the aortic arch, and lateral margin of the spine on posteroanterior radiographs. On lateral radiographs, the pulmonary apex, upper border of the aortic arch, anterior border of the heart, anterior margin of the ascending aorta, and trachea were included. Forty-six posteroanterior and 40 lateral radiographs taken by CR and screen-film radiography were reviewed. CR was often superior in identifying intrathoracic structures. Marked superiority of CR to screen-film radiography in visualizing intrathoracic structures was found in 48% of peripheral zonal vessels, 63% of tracheas on posteroanterior images, 46% of lateral margins of the spine, and 60% of pulmonary apexes. The superiority of CR is due to the wide dynamic range of imaging plates and image-processing procedures. CR will make it easier to identify multiple intrathoracic structures for radiographic measurements. In a second experiment chest radiographs were taken in both deep inspiration and expiration phase with one-shot dual-energy subtraction technique using the CR system in five patients with chronic pulmonary emphysema showing abnormal pulmonary function and 5 patients without any airway obstruction diseases. Original CR plain chest images and bone-subtracted chest images were displayed on a CRT (TDF-500AS, Toshiba Medical, Tokyo) and X-ray densitometry was attempted utilizing digital values.(ABSTRACT TRUNCATED AT 250 WORDS)