دانلود رایگان مقاله مقایسه توموگرافی اشعه ایکس کامپیوتری پزشکی و صنعتی برای آزمایش غیر مخرب

Abstract

Industrial X-ray computed tomography (CT) is an emerging laboratory-based non-destructive testing technique used in a variety of applications for samples ranging from 1 mm to usually 300 mm in diameter. Usually, microCT scanners are used for industrial non-destructive testing due to the superior resolution possible compared to medical CT scanners, but it is not generally known that medical CT scanners can produce reasonable results when high resolution is not needed. As demonstrated in this case study of very dense objects, far shorter scan time is required, compared to conventional laboratory industrial CT systems, consequently being a better solution for applications such as quick scout-scans, high throughput applications and larger objects. This case study makes use of four typical industrial test objects, specifically chosen as candidates which would be expected to be too dense for relatively low-voltage medical scanners. The respective test objects were scanned with both medical and microCT scanners and the results compared for the purpose of industrial non-destructive analysis. The test objects are a steel turbine blade, a titanium casting, a concrete cylinder with aggregate stones and porosity, and a concrete block with metal fiber reinforcement.

4. Conclusions

This case study indicates that medical CT scans can produce useful data in significantly reduced times, making it a definite good option for non-destructive testing, especially for large numbers of samples and where only moderate resolution is required. Another advantage is its ability to scan larger objects than typical microCT systems (e.g. an entire concrete block could not be scanned in one scan volume on a microCT, but could have been done by 3-part scanning tripling the scan time in this case up to more than 4 hours). Data set sizes are significantly reduced, making its analysis and quick assessment faster with reduced computational power necessary. However, industrial non-destructive analysis is usually not available at medical CT facilities, therefore analysis should still be done at industrial CT facilities or with industrial CT software. The chosen test objects where specifically selected as challenging objects for microCT, i.e. they are all on the extreme limit of sample size and density possible for laboratory microCT (up to 225 kV), and therefore smaller or less dense objects will result in improved quality with respect to medical CT scans. However, larger objects will be impossible to scan with typical laboratory microCT, while medical CT could produce reasonable results, especially when only moderate resolution is required. Considering the artifacts, medical CT is however not good enough for industrial testing in general, but can find application in niche areas and for high throughput applications where critical components are tested which would not have been otherwise tested due to the time and cost constraints of typical microCT. It is envisaged that industrial non-destructive testing facilities could make use of both methods.