Journal of X-Ray Science and Technology - Volume 15, issue 3
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Journal of X-Ray Science and Technology is an international journal designed for the diverse community (biomedical, industrial and academic) of users and developers of novel x-ray imaging techniques. The purpose of the journal is to provide clear and full coverage of new developments and applications in the field.
Areas such as x-ray microlithography, x-ray astronomy and medical x-ray imaging as well as new technologies arising from fields traditionally considered unrelated to x rays (semiconductor processing, accelerator technology, ionizing and non-ionizing medical diagnostic and therapeutic modalities, etc.) present opportunities for research that can meet new challenges as they arise.
Abstract: Homeostasis in concentration of essential elements and its abnormality due to cancer have been observed for single hair samples by X-ray fluorescence analysis using synchrotron radiation. Ca, Br and K are associated with the cellular signal transduction and were found to have two levels of upper and lower concentrations in hair due to gating their ion channels of hair matrix cells where the channels opened by deficiency of the element. The analysis of patient hair from…its root to tip revealed that breast cancer accompanied the characteristic long-period decrease from the upper to the lower level of hair [Ca] that had started 8 to 36 months before finding the cancer; the decreasing profiles were unique to cancer as a competitive process between parathyroid hormone PTH and cancer-induced PTH-related protein by comparison with those for non-cancer subjects. It is concluded that breast cancer originates in disturbance of the signal transduction by the high [Ca] in cells. The observed [Br] in hair gave signs for serious diseases such as renal failure. K deficiency was observed for a half of healthy subjects, similarly to the population of hypertension in Japan. Hair from hypertension patients showed K deficiency, unless taking depressor. Most of elements such as Fe, Cu and Zn in hair were indicators for the liver functions of their storage and excretion.
Abstract: Recently, the Palamodov algorithm, which was formulated for exact cone-beam reconstruction from data collected along a continuous locus, has been proven to be an excellent approximate algorithm for general cone beam reconstruction. The filtration-backprojection framework of the Palamodov algorithm is efficient for sequential and parallel implementation because its filtration step only involves a 1-D shift-invariant filtering along the tangent direction of the scanning trajectory. On the other hand, the generalized Feldkamp algorithm…proposed by Wang et al.~also allows approximate general cone beam reconstruction. In this paper, we report a numerical study comparing these two approximate methods for the cases of helical and saddle curves. In this study, the image quality is evaluated in terms of mean square error (MSE), modulation transform function (MTF), etc. The results demonstrate that the Palamodov algorithm consistently performs similar or better than the generalized Feldkamp algorithm.
Abstract: X-ray radiographic technique is widely used as Nondestructive Testing (NDT) for inspection of welding joints. The quality of X-ray images is frequently sensitive for noise, lighting and working place surroundings. Therefore, such images need to be carefully examined to identify welding discontinuities. However, the human interpretative are usually contradictory and may cause confusion. Present work has proposed an image processing technique based on frequency domain processing to clarify the X-ray radiographic images…taken for different welding discontinuities. The images are captured using low-resolution video camera and high-resolution digital camera. Preprocessing imaging tasks are performed to reduce the noise in the low-resolution video sequence images. Subsequently, low-pass followed by emphasis high-pass frequency filters are applied to enhance the images with appropriate cut-off frequencies. It is found that high-frequency domain image filtering is enhancing the morphological features of the X-ray images. The enhanced images become visually cleared and the welding discontinuities are possibility accessible.
Keywords: Welding discontinuities, frequency domain analysis, image filtering, image enhancement, nondestructive testing, X-ray film
Abstract: In recent years, image reconstruction methods for cone-beam computed tomography (CT) have been widely discussed with default setting of geometry that the normal vector of the detector plane passing the X ray source crosses the rotation axis. However, this may not be true in reality. In this paper, we defined a cone beam CT with freedom in the arrangement of an X ray source and detector. A circular trajectory scan is studied. An FDK-type reconstruction is…derived for this kind of CT geometry. The reconstruction formulae are similar to the well-known FDK. The implementation is simple and straightforward. It reduces to the original FDK if the default setting of geometry for traditional circular CT is applied. Hence, one can adapt our method directly to current applications and allow more flexibility in system arrangement. A computer-simulation study is performed to validate the reconstruction algorithm and demonstrate its performance. The proposed algorithm for a free-geometry cone beam CT can reconstruct the exact mid-plane image of the object and a volume within a reasonable cone angle with very small error like FDK for traditional CT.
Abstract: Scattering cross sections of radiation interactions with matter form the foundation for diagnostic x-ray imaging, nuclear medicine, and radiotherapy. These cross sections are typically presented as numerical charts in medical physics literature or complicated formulas in quantum electrodynamics literature. There seems to be a lack of comprehensible explanations for these cross section coefficients. Intuitive dimensional estimations of the dependences on photon energy and atomic number for radiation matter interaction cross sections are…provided using elementary concepts of classical and quantum physics for Compton scattering, Rayleigh scattering, photoelectric effects, and pair production. This easy-to-understand approach is found to yield dimensional relations similar to that derived from quantum electrodynamics.
Keywords: Dimensional analysis, interaction between radiation and matter, interaction cross sections, compton scattering, rayleigh scattering, photoelectric effects, pair production