Quality improvement of general anteroposterior radiographic image of vertebral body according to optimum angle of incidence.

OBJECTIVE: In this study, we present an appropriate angle of incidence to reduce the distortions in images of L4 and L5 during a general anteroposterior radiograph examination. METHOD: We selected 170 patients who had normal radiological findings among those who underwent anteroposterior and lateral examination for lumbar vertebrae. An optimum angle of incidence wa suggested through the statistical analysis by measuring the lumbar lordosis angle and the intervertebral disc angle in these 170 patients. RESULT: We suggested the incident angle (10.28°) of L4 and the incident angle (23.49°) of L5. We compared the distorted area ratios when the incident angle was 0°, 10°, and 23.5° using the ATOM® phantom. The ratio for the L4 decreased from 14.90% to 12.11% and that of the L5 decreased from 15.25% to 13.72% after applying the angle of incidence. We determined the incident angle (9.34°) of L4 and (21.26°) of L5 below 30° of LLA. Thus, we determined the incident angle (11.21°) of L4 and (25.73°) of L5 above 30° of LLA. CONCLUSION: When you apply the optimum angle of incidence, the distortion of image was minimized and an image between the joints adjacent to the anteroposterior vertebral image with an accurate structure was obtained. As a result, we were able to improve the quality of the image and enhance diagnostic information.

Unusual melting transition of nitrogen physisorbed on carbon nanotube bundles.

The melting transition of nitrogen physisorbed on close-ended single-wall nanotube bundles was investigated using synchrotron X-ray diffraction measurements. The beta-nitrogen solid diffraction peak was observed above the coverage that corresponded to the monolayer and the average size of the nitrogen solid was approximately 30 A. The diffraction peak was surprisingly maintained above the triple point of the bulk nitrogen solid. The crystal structure of N2 changed from cubic N2 (beta-phase) to hexagonal N2 (beta-phase) at 35.61 K. The melting temperature of the nano-scale solid nitrogen in the experiment was between 80 K and 90 K, however, which is about 20 K higher than the melting temperature of normal bulk nitrogen. The observed extraordinary melting behavior of nitrogen might originate from a combination of two factors, i.e., the substrate field effect of the carbon nanotube surface (the interaction between the single walled carbon nanotubes and the adsorbates) and the capillary condensation. If the substrate field effect is especially prominent, the nitrogen molecules that were adsorbed mainly in the groove region would be under 1,100-Torr pressure from the nanotube bundles, compared to the corresponding melting temperature of the bulk beta-nitrogen solid under a high pressure.