Film-based chest radiography: AMBER vs asymmetric screen-film systems

Abstract

Objective: Contrast-to-noise ratios were measured on radiographs from two types of state-of-the-art chest imaging systems (an Advanced Multiple Beam Equalization Radiography [AMBER] system and an asymmetric screen-film system) to facilitate an objective comparison of image quality.

Materials and methods: Radiographs of a chest phantom were obtained by using the AMBER system with a medium-latitude screen-film image recorder (Kodak T-MAT L film and Lanex regular screens) and a commercially available asymmetric, zero-crossover screen-film system optimized for chest radiography (Kodak InSight and InSight HC). Conventionally acquired radiographs (T-MAT L/Lanex regular) were also evaluated as a reference. Films were digitized, radiographic contrast and noise were measured in the lung-, mediastinum-, and subdiaphragm-equivalent regions of each image, and contrast-to-noise ratios were computed.

Results: Radiographic contrast and contrast-to-noise values were found to be higher on AMBER images in all chest regions when compared with radiographs obtained with the asymmetric screen-film systems (InSight contrast-to-noise ratio approximately 77% of AMBER contrast-to-noise in the lung-equivalent region, 57% in the mediastinum-equivalent region, and 43% in the subdiaphragm-equivalent region). On conventional radiographs, the contrast and contrast-to-noise values were higher than on all other image types in the lung-equivalent region and lower than on all other image types in the less well penetrated chest areas.

Conclusion: Image quality was higher, most notably in dense phantom regions, on radiographs obtained with the AMBER system than on radiographs obtained with the new asymmetric screen-film systems. Clinical studies are needed to determine whether this level of image improvement justifies the additional expense of the exposure equalization system.