Academic literature on the topic 'Radiographic measurement'

Musculoskeletal injuries are the most common injuries sustained by athletes and military recruits and can result in decreased performance and lifelong disability. So common and costly are these injuries that the American Academy of Orthopedic Surgeons has provided guidelines for future research, including recommendations for the development of a large animal model of bone injury (USDA 2001). In human and veterinary medicine, digital radiography represents the primary diagnostic tool the physician uses to diagnose skeletal injury. Advances in digital radiography have provided the veterinarian with opportunities to make both simple and complex radiographic assessments. We investigated a simple quantitative measurement of the solar, concave aspect of the distal phalanx in the horse, termed the Palmar-Metric (PM). The PM was a significant predictor of solar cup volume (p < 0.001) and negatively correlated with age (r2 = 0.28, p < 0.05) as determined from 544 radiographs of the distal phalanx from the left and right front feet. Therefore, veterinarians should be aware of the age related change in the solar, concave aspect of the distal phalanx in the horse. We hypothesized that the decrease in the degree of concavity with age may be due to demineralization and subsequent loss of bone density along the solar margin of the distal phalanx. Therefore, we investigated the quantification of optical bone density (bone OD) via complex radiographic calibration. By developing a brightness/darkness index (BDI), the greyscale of radiographs, calibrated with an aluminum marker of varying known thickness, can be compared to the average density of a cross-section of bone. At varying radiographic exposure intensity (kV) and exposure time (mAs), Al BDI was a significant predictor of bone BDI (r2 = 0.960, p < 0.001) and bone OD (r2 = 0.971, p < 0.001). This method of calibration can be utilized by the radiologist to accurately assess bone OD regardless of technique, and allow direct comparison of radiographs taken under different exposure settings. This method successfully quantifies bone OD via measurement of BDI from standardized digital radiographs, allowing for the opacity of radiographs to be truly comparable when taken under different circumstances.

Includes abstract.<br>Includes bibliographical references (leaves 112-117).<br>This study describes dose measurements made for linear slit scanning radiography (LSSR) and a dose prediction model that was developed for LSSR. The measurement and calculation methods used for determining entrance dose and effective dose (E) in conventional X-ray imaging systems were verified for use with LSSR. Entrance dose and E were obtained for LSSR and compared to dose measurements on conventional radiography units. Entrance dose measurements were made using an ionisation chamber and dosemeter; E was calculated from these entrance dose measurements using a Monte Carlo simulator. Comparisons with data from around the world showed that for most examinations the doses obtained for LSSR were considerably lower than those of conventional radiography units for the same image quality. Reasons for the low dose obtained with LSSR include scatter reduction and the beam geometry of LSSR. These results have been published as two papers in international peer reviewed journals. A new method to calculate entrance dose and effective dose for LSSR is described in the second part of this report. This method generates the energy spectrum for a particular set of technique factors, simulates a filter through which the beam is attenuated and then calculates entrance dose directly from this energy spectrum. The energy spectrum is then combined with previously generated organ energy absorption data for a standard sized patient to calculate effective dose to a standard sized patient.Energy imparted for different patient thicknesses can then be used to adjust the effective dose to a patient of any size. This method is performed for a large number of slit beams moving across the body in order to more effectively simulate LSSR. This also allows examinations with technique factors that vary for different parts of the anatomy to be simulated. This method was tested against measured data and Monte Carlo simulations. This model was shown to be accurate, while being specifically suited to LSSR and being considerably faster than Monte Carlo simulations.

Thesis (M.S.)--University of Florida, 2002.<br>Title from title page of source document. Document formatted into pages; contains xii, 91 p.; also contains graphics. Includes vita. Includes bibliographical references.

Dynamic flow of material has been studied using fast neutron radiography (FNR) and positron emission particle tracking (PEPT). A new fast neutron imaging system was commissioned at The South African Nuclear Energy Corporation, Pretoria, as part of this study, although FNR measurements were ultimately performed at PhysikalischTechnische Bundesanstalt (PTB), Braunschweig. The PEPT studies were undertaken at the PEPT Cape Town facility located at iThemba LABS, Cape Town. The steady state motion of media, within a laboratory-scale tumbling mill, was studied for a range of speed and media mixes, using both FNR and PEPT. Several operational parameters were derived from the data, which could be related to potential improvements to the milling efficiency. The blending of FNR and PEPT data for the study of steady state flow, was explored for the first time. In addition, the flow of water through porous media was studied using FNR, which enabled the determination of the hydraulic conductivity, and hence intrinsic permeability, of the media within the column. The potential of using FNR, without or without PEPT, for the study of material in motion is discussed.