Contrast enhancement in microplanar beam radiography

In x-ray radiography, the target produces a useful shadow from absorption of the primary beam, while the scattered radiation into the off-target region decreases the contrast of the target image. A bundle of closely spaced microplanar beams can reduce the scattered radiation and give superior image contrast compared with a single macrobeam of the same dimensions. To further reduce the scattered radiation and increase the image contrast, we place an air gap between the tissue phantom and the detector. The primary and scattered photon flux of a single microplanar beam is measured as a function of thickness inside the phantom and in the air gap. Results show that a bundle of closely spaced, microplanar beams increase the image contrast by 22% and a 2 cm air gap decreases the scattered photon flux by about half, improving the contrast by an additional 16%. Thus an overall improvement of 41% in contrast can be achieved with microplanar beam radiography.