Dose Reduction in Patients Undergoing Chest Imaging: Digital Amorphous Silicon Flat-Panel Detector Radiography Versus Conventional Film-Screen Radiography and Phosphor-Based Computed Radiography

Abstract

We sought to compare the radiation dose delivered to patients undergoing clinical chest imaging on a full-field digital amorphous silicon flat-panel detector radiography system with the doses delivered by a state-of-the-art conventional film-screen radiography system and a storage phosphor-based computed radiography system. Image quality was evaluated to ensure that the potential reduction in radiation dose did not result in decreased image acuity. SUBJECTS AND METHODS. Three groups of 100 patients each were examined using the amorphous silicon flat-panel detector, film-screen, or computed radiography systems. All patient groups were matched for body mass index, sex, and age. To measure the entrance skin dose, we attached 24 calibrated thermoluminescent dosimeters to every patient. The calculation of the effective dose, which represents the risk of late radiation-induced effects, was based on measurements on an anthropomorphic phantom. Image quality of all three systems was evaluated by five experienced radiologists, using the European Quality Criteria for Chest Radiology. In addition, a contrast-detail phantom study was set up to assess the low-contrast detection of all three systems. The amorphous silicon flat-panel detector radiography system allowed an important and significant reduction in both entrance skin dose and effective dose compared with the film-screen radiography (x 2.7 decrease) or computed radiography (x 1.7 decrease) system. In addition, image quality produced by the amorphous silicon flat-panel detector radiography system was significantly better than the image quality produced by the film-screen or computed radiography systems, confirming that the dose reduction was not detrimental to image quality. The introduction of digital flat-panel radiography systems based on amorphous silicon and cesium iodide is an important step forward in chest imaging that offers improved image quality combined with a significant reduction in the patient radiation dose.