RADIOGRAPHIC/FLUOROSCOPIC IMAGING SYSTEM WITH REDUCED PATIENT DOSE AND FASTER TRANSITIONS BETWEEN RADIOGRAPHIC AND FLUOROSCOPIC MODES

摘要

A radiographic/fluoroscopic imagining system provides rapid transition from fluoroscopic to radiographic imaging mode by maintaining the X-ray tube high voltage, increasing the filament current, allowing X-ray tube current to increase toward the desired radiographic current, and terminating exposure when the desired X-ray dose has been achieved. Rapid transition from radiographic to fluoroscopic imaging mode is provided by reducing x-ray tube high voltage to produce an equivalent fluoroscopic-level x-ray output at high initial current , dropping filament current, and enabling ABS control of the high-voltage. As x-ray tube current drops, ABS correspondingly increase high voltage to maintain the desired output. The imaging system obtains movement-related information by analyzing a video signal (such as from fluoroscopic image or an image from an optical camera trained on the patient), or from operator movement requests. The imaging system uses movement-related information to responsively control fluoroscopic pulse rate or other imaging parameters. The imaging system can also use such information to initiate a radiographic exposure, or advance to the next step of an operator programmed examination consisting of interspersed fluoroscopic and radiographic exposures. This results in a lower dose to both t he patient and the examiner, consistent with high image quality.