Reduction of absorbed dose in storage phosphor urography by significant lowering of tube voltage and adjustment of image display parameters

Purpose: To investigate whether image quality in storage phosphor urography can be maintained when the X-ray tube voltage is significantly lowered to give a lower patient dose. Material and Methods: Initial phantom studies were used to establish exposure settings at 53 kV that gave signal-to-noise ratios for contrast media structures equivalent to those obtained at the reference kilovoltage of 69 kV. Dose area product and image quality, assessed by image quality criteria and visual grading, were then recorded for 44 patients drawn at random to be examined by either the standard or modified technique. Results: Absorbed dose could be reduced by more than 30% without any significant change in image quality in manually controlled exposures and by 13% in exposures controlled by AEC. Conclusion: It might be possible to lower the tube voltage in digital examinations involving contrast media as a means of lowering patient dose. The image display parameters need to be adjusted to maintain image quality.