2010远东论坛报告摘要之一:工业数字射线照相技术的进展
Dr. Uwe Ewert, Director and Professor
Plenary Presentation on Digital Industrial Radiology at FENDT 2010
Progress in Digital Industrial Radiology
Uwe Ewert
Federal Institute for Materials Research and testing (BAM); Berlin; Germany
The classical film based radiography is an essential part of the non destructive testing technologies for detecting and evaluation of internal flaws. It is an established method for stationary and mobile inspection and its application is regulated world wide in a variety of standards. Due to the fast development in detection and computer technology the radiology changed its scope remarkably. Film replacement by digital detectors is in progress. Film replacement includes economical and ecological advantages but may also include the risk of misuse of the new technology by just taking over a technology, developed for medical application. New standards are on the way for the correct procedure. These standards do also emphasize the differences in industrial radiology in USA and Europe. Computed Radiology (CR) is the typical film replacement technique. X-ray inspection in Europe requires the High Definition (HD) CR. CR systems have typically a higher dynamic and achieve a slightly higher signal to noise ratio (SNR) than films. The SNR is limited by the fixed pattern noise of the imaging plates (IP). In house inspection allows the application of Digital Detector Arrays (DDA), especially if the part is moved to the inspection system. Differences of the characteristic of the DDA-pixels can be corrected by calibration procedures. This allows the application in the high contrast sensitivity (HCS) mode. Achievable SNR > 1000 and image integration provide a contrast sensitivity up to 10 times better than X-ray films or CR systems. DDAs are an essential tool for quality assurance as automated defect recognition, function and completeness test as well as measurement of internal and external dimensions. They allow dual energy inspection for parallel imaging and materials discrimination. Nowadays X-ray back scatter technique is used successfully in security applications with single sided access. The technology is fast and suitable for large area scanning of structures covered by metal. It is also a tool for visualization of water intrusion in honey comb structures as well as drugs and explosives in cars and under clothes of humans. New software packages for X-ray modelling are modern tools for training and experiment design. Quantitative values for the probability of detection can be calculated by calibrated modelling. These are prerequisites for POD or risk based maintenance concepts. With the development of DDAs and computer technology Computed Tomography (CT) became a standard tool in industry after about 30 years of limited laboratory application. CT devices are nowadays in use for a variety of applications. Large devices with linear accelerators are used e.g. for inspection of nuclear waste, rocket motors, chemical reactors etc. On the other end of the dimensional scale new concepts for nano CT allow the investigation of microscopic processes. More and more interest in industry is focused to the exact determination of dimensions. Accurate dimensional measurement of inner structures by CT is more and more accepted by industry. Tomography is also in use for mobile inspection. A rotational (tomographic) and translational (laminographic) scanner and its application for industrial applications from nuclear power to aircraft industry is presented.
Keywords: Digital radiography, computed tomography, computed radiography, digital detector arrays, high contrast sensitivity, high definition, mobile inspection, dimensional measurement, back scatter technique.