Cost-effective micro-CT system for non-destructive testing of titanium 3D printed medical components

Micro-CT imaging can be used as an effective method for non-destructive testing (NDT) of metal 3D printed parts–including titanium biomedical components fabricated using laser powder-bed-fusion (LPBF). Unfortunately, the cost of commercially available micro-CT scanners renders routine NDT for biomed...

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Bibliographic Details
Published in:	PloS one 2022-10, Vol.17 (10), p.e0275732-e0275732
Main Authors:	Cobos, Santiago Fabian, Norley, Christopher James, Pollmann, Steven Ingo, Holdsworth, David Wayne
Format:	Article
Language:	eng
Subjects:	Biology and Life Sciences Biomedical materials Cameras Computed tomography Cost benefit analysis CT imaging Diameters Digital cameras Engineering and Technology Evaluation Lenses Light Low cost Management systems Mechanical properties Medical imaging Medicine and Health Sciences Noise levels Nondestructive testing Performance evaluation Phosphors Physical Sciences Porosity Process control Process controls Quality assurance Rare earth elements Research and Analysis Methods Scanners Sensors Surgical implants Three dimensional printing Titanium Tomography X ray detectors X ray imagery X-ray fluxes X-rays
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Summary:	Micro-CT imaging can be used as an effective method for non-destructive testing (NDT) of metal 3D printed parts–including titanium biomedical components fabricated using laser powder-bed-fusion (LPBF). Unfortunately, the cost of commercially available micro-CT scanners renders routine NDT for biomedical applications prohibitively expensive. This study describes the design, manufacturing, and implementation of a cost-effective scanner tailored for NDT of medium-size titanium 3D printed biomedical components. The main elements of the scanner; which include a low-energy (80 kVp) portable x-ray unit, and a low-cost lens-coupled detector; can be acquired with a budget less than $ 11000 USD. The low-cost detector system uses a rare-earth phosphor screen, lens-coupled to a dSLR camera (Nikon D800) in a front-lit tilted configuration. This strategy takes advantage of the improved light-sensitivity of modern full-frame CMOS camera sensors and minimizes source-to-detector distance to maximize x-ray flux. The imaging performance of the system is characterized using a comprehensive CT quality-assurance phantom, and two titanium 3D-printed test specimens. Results show that the cost-effective scanner can survey the porosity and cracks in titanium parts with thicknesses of up to 13 mm of solid metal. Quantitatively, the scanner produced geometrically stable reconstructions, with a voxel size of 118 μm, and noise levels under 55 HU. The cost-effective scanner was able to estimate the porosity of a 17 mm diameter titanium 3D-printed cylindrical lattice structure, with a 0.3% relative error. The proposed scanner will facilitate the implementation of titanium LPBF-printed components for biomedical applications by incorporating routine cost-effective NDT as part of the process control and validation steps of medical-device quality-management systems. By reducing the cost of the x-ray detector and shielding, the scan cost will be commensurate with the overall cost of the validated component.
ISSN:	1932-6203 1932-6203