Development of an X-raying High Definition System Able to Be Deployed in Production and In-service Environments

The present work describes the development of XHINIA, a novel X-ray detection system able to be deployed both in production and in-service aeronautical environments. The system is based on a portable high-resolution X-ray detection system coupled to an automatic displacement tool. The evaluation of the detection system performances as well as the detection system detectability performances are here described. Finally the displacement tool is presented and some results of in-service capabilities of the complete system (detector and displacement tool) are presented. The XHINIA system proved to be a unique and very useful tool for in-service recurrent X-ray inspections (circumferential assemblies) and also for expertises in the aeronautical field. Introduction: The use of classical X-ray based inspection systems in an aircraft maintenance environment is never an easy job. This is mainly due to the need for dark rooms nearby for the X-ray film development, no quick access to the recorded data and the restricted access to the aircraft for long periods of time for people not involved in the X-ray inspection. This last point makes this type of inspection to be executed mainly during nightshifts. Last years developments in the field of X-ray detection systems were made in the direction of portability, high resolution and high quantum efficiency solutions. Nowadays digital X-ray detection systems become a real alternative to the classical X-ray films in the field of the aerospace Non Destructive Testing. The present work describes a novel X-ray inspection system (XHINIA) based on a digital high-resolution portable X-ray detector coupled to an automatic displacement tool enabling both aeronautical in-service and in-production inspections. XHINIA stands for X-ray system with High resolution Numerical Imaging and Automatic displacement. A view of the main component of the XHINIA system, the detector, and of NDT Expert X-ray bunker installation is shown in figure 1. The detector is a customized ImageStar camera model from Photonics Science with a fibre optic taper to couple the information from the scintilator to a high-resolution CCD camera. This customisation focused in large active window (at least 3 rivet lines should be able to be inspected at the same time) and high quantum efficiency (by a correct definition of the scintilator material and thickness). These points were the guarantee for an effective detection of aeronautical flaws (fatigue cracks, gas holes, metal inclusions...). The chosen detector had a 70mm X 70mm rectangular window and a gadolinium oxysulphide scintillator with an entrance resolution of 34 μm. Figure 1 – XHINIA at NDT Expert facilities and detailed view of the ImageStar detection camera. Results: 2.1: Detector Characterization The characterisation of the ImageStar detector was necessary to determine the parameters that will be used to compare the intrinsic performances of the detector with the ones of the classical film. In literature one can see that the accurate measurement of a digital X-ray detector image quality is based on the Detective Quantum Efficiency (DQE). This parameter measures the combined effect of the noise and contrast performance of an imaging system, expressed as a function of the object detail. The determination of the DQE relies on the determination of the Modulation Transfer Function (MTF) and the Noise Power Spectrum (NPS). This measurement is based on the line pair phantom profile. Figure 2 shows the line pair phantom obtained by the Imagestar detection system. DQE comparison between the ImageStar and the Kodak M100 film 0 10 20 30 40 50 60 70 80 90 100 2 2,3 2,6 2,9 3,2 3,5 3,8 4,1 4,4 4,7 5 5,3 5,6 5,9 Spatial frequency (Lp/mm) % D Q E % DQE ImageStar