Effectiveness of antiscatter grids in digital radiography. A phantom study.

INTRODUCTION: With ever-increasing interest in bedside radiography using digital imaging techniques, one question often asked is whether and which antiscatter grid should be used to reduce the effects of scattered radiation. In this article, the authors quantitatively analyze and compare images obtained with a flexible circular hole (FCH) grid, a conventional 6:1 focused grid, or without a grid.
METHODS: Scatter-to-primary ratios (SPRs), contrast signals, and contrast-to-noise ratios (CNRs) were measured for fixed patient exposure and were compared at various locations in the images of an anthropomorphic chest phantom.
RESULTS: Although both grids resulted in greater contrast signals, a significant improvement of the CNR was achieved only in the upper and middle mediastinum regions when the conventional grid was used. With the FCH grid, the CNR is degraded at most locations in the chest image. DISCUSSION: Our results indicate that at fixed exposure level, the use of either grid yields only marginal improvement, at best, in bedside digital chest radiography.