Application of a digital beam attenuator to chest radiography

Although image quality in chest radiography can be improved dramatically with compensat-ing attenuators, it is difficult to match attenuator geometry to that of the patient and to properly position the filter in the x-ray beam. We are developing a system which will fabricate a compensating filter specific for individual patient anatomy and position the filter automatically. A low-dose image is acquired from which the attenuator is designed using a hardwired algorithm. The attenuator then is typed in multiple layers of a cerium oxide material onto a sheet of paper with a dot-matrix printer. Following positioning of the attenuator in the x-ray beam, the final compensated image is acquired with a photographic or electronic detector.Initial studies with our prototype digital beam attenuator have produced images with improved image quality. The improvement occurs because the attenuator allows the entire image to be placed in the linear portion of the film characteristic curve. In addition, decreased scatter fractions and increased signal-to-noise contribute to improved visualization of low- contrast signals behind the most attenuating regions of the patient. © 1984 SPIE.

Duke Scholars

Author James T. Dobbins III Radiology