Confocal 3D Micro-XRF is a well established and none-destructive analytical method which has a wide range of fields for applications such as environmental science, archaeology, material science and so on. This kind of technique showed dramatic results in 3D image reconstruction, surface morphology and elemental depth sensitive profiles. Therefore, 3D Micro-XRF analysis method based on a confocal X-ray set-up is very suitable for evaluation and illustration with depth sensitive investigation of oil paintings. It is meaningful to characterize the surface elemental distribution in different layer depth by surface scanning. In this work, a 3D Micro-XRF experimental set-up is established based on a Mo target X-ray source. The operated voltage is 20kV and the currents is 0.5mA. The core optical components, two polycapillary X-ray lenses were designed and manufactured by the Key Laboratory of Beam Technology of the Ministry of Education, Beijing Normal University. The FWHMs of the confocal volume is 33.0 μm , 32.4 Μm and 35 μm in three dimensions, respectively. With a proposed progressive approximation method, a modern oil painting segament was anlysed using 3D Micro-XRF spectroscopy. The surface elemental distributions were mapped through surface scanning in different motor steps. This investigation can be referred for furture works that attempt to answer for questions on painting techniques, pigmant palette, production process, counterfeit identification and so on.
The combination of an absorption sheet, a high count rate detector and a low-power micro-focus source is used to simultaneously measure the transmission of the polycapillary focusing optical lens in a large energy range. This method places the micro-focus source, the absorber and the detector in a line, has highly operability in actual measurement. The X-rays below 8 keV were completely absorbed when adding the aluminum absorption sheet, and the transmission efficiency of the lens to X-rays below 8 keV was not measured. After the absorption sheet is added, the attenuation of the X-ray is not simply an exponential decay, but also the Compton scattering effect was involved.
Poly-capillary X-ray lens provided a special mechanism to control X-ray radiation. In recent reported works, polycapillary X-ray lens started to be applied in medical imaging fields. The use of poly-capillary X-ray lens in medical imaging systems brought proper benefits in Compton scattering rejection and resolution enhancement. However, the Xray intensity distribution of the output has unsatisfied uniformity when using conventional poly-capillary lens if the primary rays emitted by a common X-ray tube. Uneven intensity distribution will cause problems such as details loss and longer exposure time for better reconstruction results. In this work, a new type of poly-capillary X-ray collimating lens was introduced for medical imaging. Different from the conventional ones, this kind of lens was divided into three regions and subarray units of different diameter channels were placed in their corresponding regions. A program was written based on ray-tracing method for optical design and imaging simulation. The optical properties of this new type collimating lens were tested, using a 50.0μm Cu target X-ray tube with 20.0kV voltage and 0.2mA currents. A plateau region that had good uniformity which is 4.0mm in diameter was obtained. In addition, X-ray transmission imaging experiments for small samples showed improvements in imaging qualities using this new optical component. Although the existence of manufacturing difficulties effects the finished product quality, this new kind of X-ray poly-capillary lens shows its potential in medical imaging.
X ray CT is a vital technology for inspecting the internal structure of some objects. Various computing method models have been used to CT reconstruction. When image of the scanned object is recorded by the detector unit of finite area, the strip-based projection model is more suitable. In this paper, a simultaneous algebraic reconstruction technique (SART) for strip-based parallel beam projection model have been adopted. Furthermore, in order to reduce the radiation dose and avoid the blurring effect resulting from changes in physical and chemical properties of specimens during scanning, it is necessary to reduce the number of step-scanning. This algorithm combined with cubic spline interpolation can reconstruct high quality CT images in a small amount of data projection in numerical simulation.