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

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.

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.

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.

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.