Description and initial clinical study of a digital chest X-ray selenium detector based system (Thoravision) [Descrizione e valutazione clinica preliminare di un sistema radiografico digitale del torace con rivelatore al selenio (Thoravision)]

The authors describe an innovative digital chest imaging system (Thoravision, Philips Medical System) based on a selenium detector directly converting X-rays in electric charges detectable by electrometers, amplified and digitalized to be sent to the imaging processor. The study was performed on a series of up to 7000 digital chest X-ray examinations and a sample of 173 cases was selected on the basis of particular diseases and pathologic patterns. In the latter case, digital and conventional radiographic techniques were compared. According to this analysis, the digital system was slightly superior in detecting anatomical details, small pleural effusions (3 cases) and slight low-contrast interstitial pathologic changes, mainly in apical (12 cases) and retrocardiac (19 cases) lung areas. The conventional screen-film system better showed small hilar calcifications (2 cases). From the protection viewpoint, at equivalent entrance doses, .15-.26 Gy/cm2 of dose-area product (DAP) values were reported with the digital system, using a tension of 150 kV in orthogonal projections, which are considerably lower than .25-.70 Gy/cm2 measured with the conventional technique. Moreover, Thoravision permitted to perform up to 100 exposures/hour, using a phantom, and 15-20 digital chest examinations/hour, versus the average 12-15 with the conventional screen-film system. The initial results are very encouraging from the clinical and cost-effectiveness viewpoints, thanks to higher Thoravision productivity and to exam optimization, even though wider and prolonged experience plus a careful study of diagnostic accuracy, sensitivity and specificity in each group of chest conditions is advisable, to assess the real innovative impact of this digital chest imaging system.