This application proposes the development, and scientific and clinical evaluation of an advanced digital radiographic system based on an improved large-field kinestatic charge detector (KCD) and associated data acquisition system mounted on a custom-designed clinical gantry. Based on results from a prototype large-field KCD system, this system will produce diagnostic images of quality (both spatial resolution and contrast resolution) substantially better than current clinical radiographic techniques, i.e., film/screen (F/S) and storage phosphor (SP) systems. Extrapolations from the prototype KCD scanner predict that the advanced system will have spatial resolution up to 10 cy/mm, quantum efficiency of 90 percent with detective quantum efficiency of 70 percent at 120 kVp based on an increased x-ray beam width of 2 cm, an optimized Frisch grid design, improved x-ray beam monitors, redesigned data acquisition electronics and improved signal processing. In addition, continuing research will be conducted on dual-energy imaging. The system will incorporate 2048 detector channels at 0.2, 0.15, and 0.1 mm signal electrode spacing and will be capable of storing up to 6144 data samples per channel, or up to 12 million samples/image. Thus, using a magnification of 1.1, pixel dimensions of 90-180 um x 10-180 um are available. These can be interpolated/averaged to any square pixel size in the range of approximately 25 x 25 um to 180 x 180 um, smaller than those available with other large-field digital radiographic techniques. The system's image quality parameters will be modeled and measured using test patterns and mechanical phantoms. A preclinical evaluation of image quality will be made using bone and preserved soft tissue specimens as well as an anthropomorphic chest phantom. Then, a clinical evaluation of the KCD system will made on 200 volunteer patients. Fifty patients (25 normal and 25 abnormal) will be studied in each of four classes of disease: interstitial lung disease and nondisplaced scaphoid bone fractures (requiring excellent spatial resolution) and metastatic disease and sarcoid adenopathy (requiring excellent spatial resolution). The major impact of this research on health care will be improved diagnosis, reduced patient dose, and the additional advantages of instant digital radiography and dual-energy imaging.
