title: Real-time digital K-edge subtraction fluoroscopy.
abstract: We report in vitro and in vivo trials of K-edge fluoroscopy, by which iodine contrast concentration is displayed live, with tissue and bone images suppressed, free of patient-motion artifacts. Iodine and cerium, 125 and 225 mg/cm2 respectively, filter alternate TV fields of cine-pulsed 50 KVP x-rays. Weighted subtraction of successive TV fields isolates the iodine image and simultaneously minimizes artifacts. Digital techniques are used in real time. At our present x-ray tube limit, 500 mA instantaneous current, the patient exposure is 180 mR/sec and quantum mottle limits the image quality. Integrating four successive difference images provides a compromise between mottle and smoothly moving displays. Cardiovascular images of a 17-kg dog, using 1 ml/kg Renografin-60 injected into a foreleg vein, show that a 15-cm chest thickness is our present practical maximum. This method may be useful in diagnosing cardiovascular anomalies in infants without catheterization or suspension of breathing.
mesh_terms: D000818:Animals; D003287:Contrast Media; D004285:Dogs; D005471:Fluoroscopy / Q000379:methods*; D006321:Heart / Q000000981:diagnostic imaging; D007455:Iodine; D008961:Models, Structural; D013382:Subtraction Technique
chemical_list: D003287:Contrast Media; D007455:Iodine