<title>Automatic detection of the useful image data from digital x-ray detectors</title>

Abstract

Typical digital x-ray image detectors in current use, or under development, provide a dynamic range of digital values which significantly exceed the actual range of useful diagnostic data for any given exposure condition. It becomes a task of the digital detection system to provide recognition of the useful data values and to provide appropriate post processing to produce diagnostically useful display image. In this paper we describe a technique which was developed to automatically useful display image. In this paper we describe a technique which was developed to automatically define the range of useful image data values. Reference values are derived from a histogram, and it is integral, of the detector's output. These reference values, along with exam specific parameters, are used in exam specific algorithms to define the range of digital values to be included in a diagnostic display image.The display image values are gray scale processed to produce an optimized soft or hard copy image data set. Using the described algorithms we have demonstrated the automated production of hard copy images from a digital detector system which are comparable to properly exposed conventional radiographs. These algorithms automatically compensates for exposure technique and subject contrast characteristics. The algorithms were developed for the Sterling Direct Radiography digital x-ray detector system; however, they are applicable to any digital x-ray image detector system. The technique described is based on the digital input values which represent log exposure values. If linear values are provided, a log conversion must be made preceding the described technique.