Rεςεαρch

X-ray collimator shutter detection by Active-Rods

In digital radiograph image processing, one essential step is to automatically outline the exposure area enclosed by collimator blades. The region of interest (ROI) facilitates only useful image data to be processed desirably for diagnosis, stored and transmitted. Failed detections cause severe image quality degradation. The off-focus radiation artifacts, system setup geometrical errors and illumination non-uniformity caused by the heel effects makes it challenging to develop a high performance image-driven automatic ROI detector. We devise a technique, called Active-Rods, to seek straight line open boundaries. Rod translations and rotations are driven by the forces and torques via minimization of an energy functional of both local edges and regional statistics. Our method is capable of detecting the exposure regions correctly under adverse shutter settings such as non-parallel opposite edges, tilt edges, and non-uniform illumination. And it is resilient to off-focus radiation artifacts.