[Use of multi-grid screens in intensive care units]

Bedside chest radiographic examinations in intensive care units with grids and high kilovoltage-peak settings are impaired by artifacts caused by the angulation of the grid (grid cutoff). We have tried to optimize the use of grids in bedside chest radiographic examinations. The sensitivity to the effect of grid cutoff was examined in two grids with the same grid ratio (12:1) but different numbers of lamelle per cm (40 versus 70) using a water-phantom. The alignment of the grid in a bedside setting was optimised. 100 chest examinations in the intensive care unit were compared by five radiologists according to ten criteria. Grids with a high number of lamelle per cm (70) proved to be less sensitive to the effects of grid cutoff. By positioning the grid with the lamelle vertical to patient's body-axis, asymmetric exposure of the lungs could be avoided. In addition, this setting allows an easy alignment of the grid by adjusting the grid together with the moveable part of the patient's bed. In examinations with grids, the advantages of high kilovoltage-peak setting were apparent. Bedside radiographic examinations in intensive care units with grids with a high number of lamelle and high-kilovoltage-peak setting can be performed without any major additional effort. By this method the image quality can be improved, especially in lungs with increased scatter-radiation.