SINGLE-ENERGY AND DUAL-ENERGY CT WITH MONOCHROMATIC SYNCHROTRON X-RAYS

We explored the potential for clinical research of computed tomography (CT) with monochromatic x-rays using the preclinical multiple energy computed tomography (MECT) system at the National Synchrotron Light So urce. MECT has a Bred, horizontal fan beam with a subject apparatus ro tating about a vertical axis; it will be used for imaging the human he ad and neck. Two CdWO4-photodiode array detectors with different spati al resolutions were used. A 10.5 cm diameter acrylic phantom was image d with MECT at 43 keV and with a conventional CT (CCT) at 80 kVp: spat ial resolution approximate to 6.5 line pairs (lp)/cm for both; slice h eight, 2.6 mm for MECT against 3.0 mm for CCT; surface dose, 3.1 cGy f or MECT against 2.0 cGy for CCT. The resultant image noise was 1.5 HU for MECT against 3 HU for CCT. Computer simulations of the same images with more precisely matched spatial resolution, slice height and dose indicated an image-noise ratio of 1.4:1.0 for CCT against MECT. A 13. 5 cm diameter acrylic phantom imaged with MECT at approximate to 0.1 k eV above the iodine K edge and with CCT showed, for a 240 mu g l ml(-1 ) solution, an image contrast of 26 HU for MECT and 13 and 9 HU for th e 80 and 100 kVp CCT, respectively. The corresponding numbers from com puter simulation of the same images were 26, 12, and 9 HU, respectivel y. MECT's potential for use in clinical research is discussed.