Detection of radiographic findings in lung fibrosis using storage phosphor plates

The aim of this work was to examine the influence of the filter kernel size on the detectability of differing radiological findings in interstitial lung disease. In 97 patients with confirmed pulmonary fibrosis chest radiographs were obtained with a film-screen system of speed class 200 and with correspondingly exposed storage phosphorous plates. The size of the filter kernel used for the image postprocessing varied between sigma 5 and sigma 70. The detectability of interstitial lung changes was evaluated independently by eight readers on the basis of a defined rating system. The results were analysed using multifactorial analysis of variance with Scheffe test at a significance level of p = 0.05. Small kernel sizes (S 5, S 10) combined with high edge enhancement were only of benefit in the imaging of septal lines, but reduced the detectability of nodular and reticular structures. Good detail detectability of both micronodules and septal lines was obtained with a medium kernel size of sigma 40. Storage phosphor radiography utilizing the appropriate choice of postprocessing parameters provides equivalent image quality for evaluating interstitial lung changes compared with a modern film-screen technique.