High-dynamic-range micro-CT for nondestructive testing of titanium 3D-printed medical components

Area of Science:

• Medical Imaging
• Materials Science
• Non-Destructive Testing (NDT)

Background:

• Industrial micro-CT scanners are vital for NDT of 3D-printed medical components but often require expensive, high-energy X-ray sources.
• Low-cost X-ray units are limited by signal loss in highly attenuating materials, causing artifacts and unreliable NDT.
• Existing limitations make routine NDT of metal medical components prohibitively expensive.

Purpose of the Study:

• To develop and implement a dual-exposure technique to extend the dynamic range (DR) of a low-energy micro-CT scanner.
• To improve the signal-to-noise ratio in highly attenuated regions for NDT of 3D-printed medical components.
• To enable cost-effective NDT of metal medical parts using accessible X-ray technology.

Main Methods:

• Implemented a high-dynamic-range CT (HDR-CT) technique by combining projection images from two exposure levels, adjusting integration times.
• Evaluated the HDR-CT technique using titanium-alloy test samples, including a resolution phantom and porous cylinders with varying porosities (60-90%).
• Assessed improvements in void visualization and overall image quality compared to conventional CT scans.

Main Results:

• The HDR-CT technique effectively increased the scanner's native 12-bit dynamic range to an effective 14-16 bits.
• Projection images acquired at two exposure levels were successfully combined, enhancing signal in high-attenuation areas.
• Void visualization and image conspicuity were significantly improved in HDR-CT reconstructions.

Conclusions:

• The HDR-CT technique successfully extends the dynamic range of low-cost micro-CT systems.
• This method offers improved contrast-to-noise ratio and defect visualization for NDT of 3D-printed metal medical components.
• HDR-CT presents a promising, cost-effective solution for routine NDT of medium-sized titanium-alloy medical parts.