The authors describe a rectilinear scanner-head assembly containing an x-ray tube and a Si(Li) detector developed to stimulate and detect fluorescence from intrinsic iodine in the thyroid. Various operational parameters were evaluated. Because of the abundant supply of photons, a scanning distance of 3 inches (7.62 cm) could be used. The full width at half maximum at this distance was 0.52 cm. Optimal exposure was obtained at 80 kVp, 0.5 mA with a copper-aluminum filter combination. The scanner with an x-ray generator appears to be a workable alternative to imaging devices using long-lived radionuclide sources.