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  • 1
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    Fractal dimension analysis of weight-bearing bones of rats during skeletal unloading (2001)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Fractal analysis was used to quantify changes in trabecular bone induced through the use of a rat tail-suspension model to simulate microgravity-induced osteopenia. Fractal dimensions were estimated from digitized radiographs obtained from tail-suspended and ambulatory rats. Fifty 4-month-old male Sprague-Dawley rats were divided into groups of 24 ambulatory (control) and 26 suspended (test) animals. Rats of both groups were killed after periods of 1, 4, and 8 weeks. Femurs and tibiae were removed and radiographed with standard intraoral films and digitized using a flatbed scanner. Square regions of interest were cropped at proximal, middle, and distal areas of each bone. Fractal dimensions were estimated from slopes of regression lines fitted to circularly averaged plots of log power vs. log spatial frequency. The results showed that the computed fractal dimensions were significantly greater for images of trabecular bones from tail-suspended groups than for ambulatory groups (p 〈 0.01) at 1 week. Periods between 1 and 4 weeks likewise yielded significantly different estimates (p 〈 0.05), consistent with an increase in bone loss. In the tibiae, the proximal regions of the suspended group produced significantly greater fractal dimensions than other regions (p 〈 0.05), which suggests they were more susceptible to unloading. The data are consistent with other studies demonstrating osteopenia in microgravity environments and the regional response to skeletal unloading. Thus, fractal analysis could be a useful technique to evaluate the structural changes of bone.
    Keywords: Life Sciences (General)
    Type: Bone (ISSN 8756-3282); Volume 29; 2; 180-4
    Format: text
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  • 2
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    Dental research: Preliminary observations and projections (1978)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The potential applicability of the Lixiscope in dentistry was investigated. Conceptual limitations on basic design requirements common to the Lixiscope are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Preliminary Appl. and Evaluation Results. Lixiscope; p 37-41
    Format: application/pdf
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  • 3
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    Analysis of fractal dimensions of rat bones from film and digital images (2001)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: OBJECTIVES: (1) To compare the effect of two different intra-oral image receptors on estimates of fractal dimension; and (2) to determine the variations in fractal dimensions between the femur, tibia and humerus of the rat and between their proximal, middle and distal regions. METHODS: The left femur, tibia and humerus from 24 4-6-month-old Sprague-Dawley rats were radiographed using intra-oral film and a charge-coupled device (CCD). Films were digitized at a pixel density comparable to the CCD using a flat-bed scanner. Square regions of interest were selected from proximal, middle, and distal regions of each bone. Fractal dimensions were estimated from the slope of regression lines fitted to plots of log power against log spatial frequency. RESULTS: The fractal dimensions estimates from digitized films were significantly greater than those produced from the CCD (P=0.0008). Estimated fractal dimensions of three types of bone were not significantly different (P=0.0544); however, the three regions of bones were significantly different (P=0.0239). The fractal dimensions estimated from radiographs of the proximal and distal regions of the bones were lower than comparable estimates obtained from the middle region. CONCLUSIONS: Different types of image receptors significantly affect estimates of fractal dimension. There was no difference in the fractal dimensions of the different bones but the three regions differed significantly.
    Keywords: Life Sciences (General)
    Type: Dento maxillo facial radiology (ISSN 0250-832X); 30; 3; 179-83
    Format: text
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  • 4
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    The low intensity X-ray imaging scope /Lixiscope/ (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A fully portable, small-format X-ray imaging system, Lixiscope (low intensity X-ray imaging scope) is described. In the prototype, which has been built to demonstrate the feasibility of the Lixiscope concept, only well-developed and available components have been used. Consideration is given to the principles of operation of the device, some of its performance characteristics as well as possible dental, medical and industrial applications.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applications of electronic imaging systems; Seminar; Mar 30, 1978 - Mar 31, 1978; Washington, DC
    Format: text
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