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Abstract:Objective: To demonstrate the validity and reliability of volumetric quantitative computed tomography (vQCT) with multi-slice computed tomography (MSCT) and dual energy X-ray absorptiometry (DXA) for hip bone mineral density (BMD) measurements, and to compare the differences between the two techniques in discriminating postmenopausal women with osteoporosis-related vertebral fractures from those without. Methods: Ninety subjects were enrolled and divided into three groups based on the BMD values of the lumbar spine and/or the femoral neck by DXA. Groups 1 and 2 consisted of postmenopausal women with BMD changes <−2SD, with and without radiographically confirmed vertebral fracture (n=11 and 33, respectively). Group 3 comprised normal controls with BMD changes ≥−1SD (n=46). Post-MSCT (GE, LightSpeed16) scan reconstructed images of the abdominal-pelvic region, 1.25 mm thick per slice, were processed by OsteoCAD software to calculate the following parameters: volumetric BMD values of trabecular bone (TRAB), cortical bone (CORT), and integral bone (INTGL) of the left femoral neck, femoral neck axis length (NAL), and minimum cross-section area (mCSA). DXA BMD measurements of the lumbar spine (AP-SPINE) and the left femoral neck (NECK) also were performed for each subject. Results: The values of all seven parameters were significantly lower in subjects of Groups 1 and 2 than in normal postmenopausal women (P<0.05, respectively). Comparing Groups 1 and 2, 3D-TRAB and 3D-INTGL were significantly lower in postmenopausal women with vertebral fracture(s) [(109.8±9.61) and (243.3±33.0) mg/cm 3 , respectively] than in those without [(148.9±7.47) and (285.4±17.8) mg/cm 3 , respectively] (P<0.05, respectively), but no significant differences were evident in AP-SPINE or NECK BMD. Conclusion: the femoral neck-derived volumetric BMD parameters using vQCT appeared better than the DXA-derived ones in discriminating osteoporotic postmenopausal women with vertebral fractures from those without. vQCT might be useful to evaluate the effect of osteoporotic vertebral fracture status on changes in bone mass in the femoral neck.

It is important to evaluate the deformation and failure of sandstone in the foundation

Through drilling and three-dimensional scanning by C-ALS laser, the spatial position and size of mined-out area can be obtained. It can provide important technical basis for safety management and evaluation of goaf. This paper takes the stability analysis of Hidden Goaf in the third mining area of Zhoutaizi Iron Mine, Zhangbaiwan town, Luanping County as an example. After the mined-out area was drilled, the data point cloud was obtained by C-als three-dimensional Laser scanning and the three-dimensional visualization model was constructed. Write the conversion program in FISH language and import it into FLAC3D, The distribution characteristics of ground pressure, deformation, failure of surrounding rock and surface subsidence in goaf are analyzed. And it is consistent with the actual situation of the goaf, Thus it shows the feasibility of the coupling modeling technology method of C-ALS data point cloud and FLAC3D in obtaining three-dimensional feature information of goaf and determining the stability of goaf. At the same time it provides technical reference for prospecting and stability analysis of similar goaf.

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