Method for image equalization of ROI fluoroscopic images using mask localization, selection and subtraction.

In region of interest (ROI) fluoroscopy, a filter is used to drastically reduce the X-ray dose to the patient peripheral to an ROI, and mask subtraction is used to equalize the displayed image brightness. Methods are described for an optimized search to locate the ROI and select or construct a mask image using a descriptor look up table (DLUT) based on ROI size, relative ROI/periphery brightness and ROI shape and orientation. After mask subtraction, the brightness values of the periphery are comparable to those of the ROI providing for equalized display. This method was tested successfully on 50 actual fluoroscopic images of two anthromorphic phantoms. The methodology developed for real-time applications was successfully simulated in PC code and full real-time implementation is underway.