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The demand for bowel cleansing hampers participation in screening colonoscopy, while poor preparation impairs adenoma detection. A novel prepless X-ray imaging capsule for colon screening is presented; the capsule emits low dose X-rays, which are scattered by ingested contrast agent mixed with colon contents, and sensed by detectors in the capsule to generate high-resolution three-dimensional (3D) imagery of the colon without bowel cleansing. Following preliminary studies with implanted polyps in synthetic colon phantoms, bovine cadaver and live swine, and human experiments with dummy capsules (n=75), 49 patients swallowed the capsule with natural excretion in 48 after 73.2±45.4 h. Pedunculated and sessile polyps were clearly seen and validated by subsequent colonoscopy. Total radiation exposure was ultra low (0.03±0.007 mSv).

In more detail

Bowel preparation remains a major obstacle limiting complete uptake of colonoscopy for colon cancer screening.1 ,2 Therefore any test which does not require preparation would probably increase compliance.3 However, the accuracy to depict cancers as well as adenomas should not suffer substantially. A new X-ray capsule is shown in a series of proof-of-concept studies to be safe and effective in 3D reconstruction of the colonic wall and lumen including identifying adenomatous polyps.

The capsule system includes a short-lived radio isotope within a collimator housing that emits three X-ray beams in all directions, by way of a rotating miniature electric motor as the capsule scans the length of the GI tract. A small volume of ingested radiopaque contrast agent increases the contrast of the colon's walls and differentiates them from stool content. Compton backscattered photons, attenuated by the contrast agent mixed with the colon contents, and X-ray fluorescence photons emitted from the contrast agent, are …