Visibility of normal thoracic anatomic landmarks on storage phosphor digital radiography versus conventional radiography.

Background: Chest radiography is still the most frequently performed radiologic imaging study. Digital radiography is gradually replacing the conventional systems. Objectives: To compare the subjective visibility of normal ana- tomic landmarks in the chest on storage phosphor-based digital radiographs versus conventional screen-film radiographs. Methods: Digital phosphor-based and screen-film posteroanterior chest radiographs were obtained during 1 year in 140 asymptom- atic patients without any known pulmonary disease (119 men, 21 women; mean age 52.1 years, range 23-86). Both sets of films were independently compared by two experienced radiologists in different sessions. The visibility of each of the following anatomic landmarks was graded from 1 to 3: pulmonary fissures, carina, bronchi to left upper lobe, right upper lobe and left lower lobe, bronchus intermedius, anterior and posterior junctional lines, and vessels behind the heart and diaphragm. Additionally, subjective general quality impression of each radiograph was graded similarly. Statistical analyses were performed using the chi-square test. A P value less than 0.05 was considered significant. Results: Visibility with the digital images was statistically sig- nificantly higher for the carina, left lower lobe bronchus, bronchus intermedius, and vessels behind the heart and diaphragm. Sub- jective general quality impression of digital radiographs was also higher (P < 0.001). No significant visibility differences were found for pulmonary fissures or junctional lines. Conclusion: Subjective visibility of anatomic structures behind the heart and diaphragm and at the hilae is significantly improved with phosphor-based digital radiography compared with conventional screen-film radiography. This suggests that pathologic processes such as pulmonary nodules, masses or consolidations projected over those structures may be more easily and reliably depicted on digital than on conventional chest X-rays.