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TOMOHAWK - Recent Advances in Computerised X-ray Tomography using Real-time Radiography Equipment
| Content Provider | Semantic Scholar |
|---|---|
| Author | Burch, S. F. Lawrence, Peter F. |
| Copyright Year | 1993 |
| Abstract | Systems for real-time radiography, complete with computers for image processing, are regularly used for NDT. Recent work at Harwell has resulted in the development of TOMOHAWK, a PC-based system, which produces high resolution cross sectional images from real-time equipment. This is achieved through a novel approach to computerised tomography, which incorporates the latest PC-based technology for digitisation, processing and display of standard video images generated from the real-time imaging system. The TOMOHAWK software is configured in a user-friendly, menu-based environment and comprises a comprehensive set of programs for data acquisition, tomographic reconstruction and image display. TOMOHAWK can either be incorporated into new turn-key systems, or used to upgrade existing real-time equipment. Since the development by Hounsfield of the first commercial scanner in the early 1970's, the advantages of computer-assisted tomography (CAT) over conventional radiography were rapidly recognised in medicine, where the technique is now in widespread and routine use. The main advantage of CAT scanning is that a true cross-sectional image is obtained, instead of the shadow-graph obtained with conventional radiography. This is particularly useful when inspecting complex objects. In contrast to the medical field, CAT scanning has been slow to be developed as an NDT technique for a number of reasons, including the high cost of the necessary equipment and the length of time required for inspection. In the TOMOHAWK system, the discrete detectors used in conventional CAT scanners are replaced by a real-time imaging system, such as an image intensifier or low-light level TV camera with separate fluorescent screen. In this method, the data needed for tomography are acquired using digital image processing hardware and a computer is used to derive the cross-sectional image. One of the advantages of this technique over conventional CAT scanners is that the two-dimensional nature of the real-time imaging system can be exploited to give multiple tomographic cross-sections at different heights through the specimen, all derived from a single rotation of the object. A more recent development, in conjunction with OIS Engineering Ltd, a UK real-time radiography systems company, has been the use of a new high resolution, high dynamic range x-ray detector. With this system, images are grabbed at 1024 × 1024 pixel resolution with a dynamic range greater than 4000:1. With projected magnification of the object to be inspected, resolutions as low as 5 μm have been achieved in both digital radiography and CT modes. Special features of the software allow accurate dimensional measurements to be taken. Thus, complex castings etc which can be inspected by CT, give precision internal wall imaging for accurate thickness measurement. Another feature of the software is the ability to accurately measure areas. Both of these operations need no additional calibration from the initial equipment set-up. The system provides a fast and flexible tomographic imaging capability, and has been shown to give high quality results. |
| Starting Page | 245 |
| Ending Page | 247 |
| Page Count | 3 |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/B978-0-7506-9484-1.50029-4 |
| Alternate Webpage(s) | http://www.gbv.de/dms/bowker/toc/9780750694841.pdf |
| Alternate Webpage(s) | https://doi.org/10.1016/B978-0-7506-9484-1.50029-4 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
