AUTOMATIC DETECTION OF RADIATION FIELDS IN DIGITAL RADIOGRAPHIC IMAGES

摘要

In computerized radiography (CR) imaging, collimation is frequently employed to shield body parts from unnecessary radiation exposure and minimize radiation scattering using X-ray opaque material. The radiation field is therefore the diagnostic region of interest which has been exposed directly to X-rays. We present an image analysis system for the recognition of the collimation, or equivalently, detection of the radiation field. The purpose is to (1) facilitate optimal tone scale enhancement, which can be driven only by the diagnostically useful part of the image data, and (2) minimize the viewing flare caused by the unexposed area. This system consists of three stages of operations: (1) pixel-level detection and classification of collimation boundary transition pixels; (2) linelevel delineation of candidate collimation blades; and (3) region-level determination of the collimation configuration. This system has been reduced to practice and tested over 807 images of 11 exam types and a success rate in excess of 99/100 has been achieved for tone scale enhancement and masking. Due to the novel design of the system, its computational efficiency lends itself to online operations.