The x-ray fovea, a device for reducing x-ray dose in fluoroscopy.
The x-ray fovea (U.S. patents pending) is a device for reducing x-ray dose to patients and operations during x-ray fluoroscopy. It consists of a semitransparent collimator with an open, circular, central hole. The fovea collimator is placed at the exit of the x-ray tube, and the attenuation of the peripheral x-ray beam reduces x-ray exposure to patients and operators. The shadow caused by the x-ray fovea can be compensated using real-time image processing hardware. Accurate compensation is demonstrated for both linearly and logarithmically acquired images using a model that accounts for beam hardening in the fovea collimator. The central fovea region has improved image quality due to reduced scatter and veiling glare from the periphery. From beam-stop measurements, a 40% reduction in scatter plus veiling glare is measured using the fovea. A contrast improvement ratio of 1.5 is measured throughout the central region. In the compensated periphery, noise is increased by a factor of 1.66 because fewer photons are detected, but a small amount of temporal filtering compensates this degradation. The Roentgen area product (RAP) exposure to patients is reduced by approximately 70%, while scattered exposure to operators is reduced by approximately 60%.
Labbe
M S
MS
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106.
Chiu
M Y
MY
Rzeszotarski
M S
MS
Bani-Hashemi
A R
AR
Wilson
D L
DL
D004869:Equipment Safety; D005471:Fluoroscopy; D006801:Humans; D011835:Radiation Protection