Proof-of-Concept Dual-Energy X-Ray Discrimination of Glass and Poly(methyl methacrylate) Enabled by Carbon Nanotube Cold Cathode

Abstract

This article presents a proof-of-concept study on a quantitative dual-energy X-ray material discrimination system enabled by a high-stability carbon nanotube (CNT) cold cathode triode. Traditional thermionic X-ray sources suffer from thermal drift and long stabilization times, which compromise precision of energy sensitive measurements. In contrast, our CNT field emission source is evidenced by a 505-h stress test of the cathode chip at 10 mA emission current, and the dual-energy (DE) imaging experiments themselves were conducted at 1 mA within this validated stability envelope. We propose a robust material decomposition framework that integrates automated K-means clustering and a lower order polynomial beam hardening correction. Experimental results using borosilicate glass and poly(methyl methacrylate) (PMMA) standards demonstrate that the system can accurately decouple material types and absolute thickness. The proposed correction algorithm reduced the path-length-dependent thickness reconstruction error from approximately 15% to below 3%, achieving a thickness measurement precision with an in-sample mean absolute error of 0.04 mm and a maximum absolute error of 0.06 mm. These results validate the potential of CNT cold cathode instrumentation for high-precision industrial inspection and medical diagnostics.