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1
Davidson, Robert Andrew. "Radiographic contrast-enhancement masks in digital radiography." Thesis, The University of Sydney, 2006. http://hdl.handle.net/2123/1932.
Full textAbstract:
Radiographic film/screen (F/S) images have a narrow latitude or dynamic range. The film’s ability to record and view all the anatomy within the x-ray field is limited by this narrow dynamic range. The advent of digital radiographic means of storing and displaying radiographic images has improved the ability to record and visualise all of the anatomy. The problem still exists in digital radiography (DR) when radiographic examinations of certain anatomical regions are undertaken. In this work, the value of anatomically shaped radiographic contrast-enhancement masks (RCMs) in improving image contrast and reducing the dynamic range of images in DR was examined. Radiographic contrast-enhancement masks are digital masks that alter the radiographic contrast in DR images. The shape of these masks can be altered by the user. Anatomically shaped RCMs have been modelled on tissue compensation filters (TCFs) commonly used in F/S radiographic examinations. The prime purpose of a TCF is to reduce the dynamic range of photons reaching the image receptor and hence improve radiographic contrast in the resultant image. RCMs affect the dynamic range of the image rather than the energy source of the image, that of the x-ray photons. The research consisted of three distinct phases. The first phase was to examine physical TCFs and their effects on F/S radiographic images. Physical TCFs are used in radiographic F/S examinations to attenuate the x-ray beam to compensate for varying patient tissue thicknesses and/or densities. The effect of the TCF is to reduce resultant radiographic optical density variations in the image, allowing the viewer to observe a range of densities within the image which would otherwise not be visualised. Physical TCFs are commonly aluminium- or lead-based materials that attenuate the x-ray beam. A TCF has varying physical thickness to differentially attenuate the iii beam and is shaped for specific anatomical situations. During this project, various commonly used physical TCFs were examined. Measurements of size and thickness were made. Characteristics of linear attenuation coefficients and half-value thicknesses were delineated for various TCF materials and at various energies. The second phase of the research was to model the physical TCFs in a digital environment and apply the RCMs to DR images. The digital RCMs were created with similar characteristics to mimic the shapes to the physical TCFs. The RCM characteristics can be adjusted by the viewer of the image to suit the anatomy being imaged. Anatomically shaped RCMs were designed to assist in overcoming a limitation when viewing digital radiographic images, that of the dynamic range of the image. Anatomically shaped RCMs differ from other means of controlling the dynamic range of a digital radiographic image. It has been shown that RCMs can reduce the range of optical densities within images with a large dynamic range, to facilitate visualisation of all anatomy within the image. Physical TCFs are used within a specific range of radiographic F/S examinations. Digital radiographic images from this range of examinations were collected from various clinical radiological centres. Anatomically shaped RCMs were applied to the images to improve radiographic contrast of the images. The third phase of the research was to ascertain the benefits of the use of RCMs. Various other methods are currently in use to reduce the dynamic range of digital radiographic images. It is generally accepted that these methods also introduce noise into the image and hence reduce image quality. Quantitative comparisons of noise within the image were undertaken. The anatomically shaped RCMs introduced less noise than current methods designed to reduce the dynamic range of digital radiographic images. It was shown that RCM methods do not affect image quality. Radiographers make subjective assessment of digital radiographic image quality as part of their professional practice. To assess the subjective quality of images enhanced with anatomically shaped RCMs, a survey of radiographers and other iv qualified people was undertaken to ascertain any improvement in RCM-modified images compared to the original images. Participants were provided with eight pairs of image to compare. Questions were asked in the survey as to which image had the better range of optical densities; in which image the anatomy was easiest to visualise; which image had the simplest contrast and density manipulation for optimal visualisation; and which image had the overall highest image quality. Responses from 123 participants were received and analysed. The statistical analysis showed a higher preference by radiographers for the digital radiographic images in which the RCMs had been applied. Comparisons were made between anatomical regions and between patient-related factors of size, age and whether pathology was present in the image or not. The conclusion was drawn that digital RCMs correctly applied to digital radiographic images decrease the dynamic range of the image, allowing the entire anatomy to be visualised in one image. Radiographic contrast in the image can be maximised whilst maintaining image quality. Using RCMs in some digital radiographic examinations, radiographers will be able to present optimised images to referring clinicians. It is envisaged that correctly applied RCMs in certain radiographic examinations will enhance radiographic image quality and possibly lead to improved diagnosis from these images.
2
Davidson, Robert Andrew. "Radiographic contrast-enhancement masks in digital radiography." University of Sydney, 2006. http://hdl.handle.net/2123/1932.
Full textAbstract:
Doctor of Philosophy<br>Radiographic film/screen (F/S) images have a narrow latitude or dynamic range. The film’s ability to record and view all the anatomy within the x-ray field is limited by this narrow dynamic range. The advent of digital radiographic means of storing and displaying radiographic images has improved the ability to record and visualise all of the anatomy. The problem still exists in digital radiography (DR) when radiographic examinations of certain anatomical regions are undertaken. In this work, the value of anatomically shaped radiographic contrast-enhancement masks (RCMs) in improving image contrast and reducing the dynamic range of images in DR was examined. Radiographic contrast-enhancement masks are digital masks that alter the radiographic contrast in DR images. The shape of these masks can be altered by the user. Anatomically shaped RCMs have been modelled on tissue compensation filters (TCFs) commonly used in F/S radiographic examinations. The prime purpose of a TCF is to reduce the dynamic range of photons reaching the image receptor and hence improve radiographic contrast in the resultant image. RCMs affect the dynamic range of the image rather than the energy source of the image, that of the x-ray photons. The research consisted of three distinct phases. The first phase was to examine physical TCFs and their effects on F/S radiographic images. Physical TCFs are used in radiographic F/S examinations to attenuate the x-ray beam to compensate for varying patient tissue thicknesses and/or densities. The effect of the TCF is to reduce resultant radiographic optical density variations in the image, allowing the viewer to observe a range of densities within the image which would otherwise not be visualised. Physical TCFs are commonly aluminium- or lead-based materials that attenuate the x-ray beam. A TCF has varying physical thickness to differentially attenuate the iii beam and is shaped for specific anatomical situations. During this project, various commonly used physical TCFs were examined. Measurements of size and thickness were made. Characteristics of linear attenuation coefficients and half-value thicknesses were delineated for various TCF materials and at various energies. The second phase of the research was to model the physical TCFs in a digital environment and apply the RCMs to DR images. The digital RCMs were created with similar characteristics to mimic the shapes to the physical TCFs. The RCM characteristics can be adjusted by the viewer of the image to suit the anatomy being imaged. Anatomically shaped RCMs were designed to assist in overcoming a limitation when viewing digital radiographic images, that of the dynamic range of the image. Anatomically shaped RCMs differ from other means of controlling the dynamic range of a digital radiographic image. It has been shown that RCMs can reduce the range of optical densities within images with a large dynamic range, to facilitate visualisation of all anatomy within the image. Physical TCFs are used within a specific range of radiographic F/S examinations. Digital radiographic images from this range of examinations were collected from various clinical radiological centres. Anatomically shaped RCMs were applied to the images to improve radiographic contrast of the images. The third phase of the research was to ascertain the benefits of the use of RCMs. Various other methods are currently in use to reduce the dynamic range of digital radiographic images. It is generally accepted that these methods also introduce noise into the image and hence reduce image quality. Quantitative comparisons of noise within the image were undertaken. The anatomically shaped RCMs introduced less noise than current methods designed to reduce the dynamic range of digital radiographic images. It was shown that RCM methods do not affect image quality. Radiographers make subjective assessment of digital radiographic image quality as part of their professional practice. To assess the subjective quality of images enhanced with anatomically shaped RCMs, a survey of radiographers and other iv qualified people was undertaken to ascertain any improvement in RCM-modified images compared to the original images. Participants were provided with eight pairs of image to compare. Questions were asked in the survey as to which image had the better range of optical densities; in which image the anatomy was easiest to visualise; which image had the simplest contrast and density manipulation for optimal visualisation; and which image had the overall highest image quality. Responses from 123 participants were received and analysed. The statistical analysis showed a higher preference by radiographers for the digital radiographic images in which the RCMs had been applied. Comparisons were made between anatomical regions and between patient-related factors of size, age and whether pathology was present in the image or not. The conclusion was drawn that digital RCMs correctly applied to digital radiographic images decrease the dynamic range of the image, allowing the entire anatomy to be visualised in one image. Radiographic contrast in the image can be maximised whilst maintaining image quality. Using RCMs in some digital radiographic examinations, radiographers will be able to present optimised images to referring clinicians. It is envisaged that correctly applied RCMs in certain radiographic examinations will enhance radiographic image quality and possibly lead to improved diagnosis from these images.
3
Hayre, Christopher Maverick. "Radiography observed : an ethnographic study exploring contemporary radiographic practice." Thesis, Canterbury Christ Church University, 2016. http://create.canterbury.ac.uk/14517/.
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This study explores the day-to-day application of digital radiography (DR) within the X-ray environment. This study presents the voices of the radiographers' untold views, attitudes and experiences of DR through the process of observing, listening, retelling and interpreting junior and senior radiographers' responses. There were three stages to this ethnographic study. Firstly, exploring 'what radiographers did' environment by observing clinical practices. This provided 'first-hand' experience of action-in-process. Secondly, 22 semi-structured interviews were undertaken, directed by emerging themes and informal discussions from the clinical observations. Semi-structured interviews provided an understanding of the experiences, behaviours and attitudes of radiographers providing a deeper understanding of the relationship between practice and context. Thirdly, X-ray experiments were undertaken contributing to 'what had been seen and said by participants'. This data was later triangulated to support the research objectives outlined in this PhD research. Observation and interview data were analysed using thematic analysis and grouped into four overarching categories; learning, radiographer challenges, ionising radiation and patient care delivery. X-ray experimental data was inputted into SPSS and later coded. The qualitative data had numerous codes, which generated themes and could be linked in order to generate theoretical descriptions. Multiple-linear regression analysis and Pearson's Correlation provide statistically significant values (p < 0.001) for the experimental models contributing to 'what had been seen and said' by radiographers in the clinical environment. This thesis provides new insights into general radiographic practices using advancing technology. The conclusions that can be drawn from the empirical data is that advancing technology has impacted the day-to-day practices of diagnostic radiographers. Complex phenomena include; current knowledge and understanding, the practice of keeping doses 'as low as reasonably practicable' and impact on patient care delivery. These insights suggest that healthcare and academic environments may require additional support in the aim of delivering optimum patient care.
4
Irvine, Michael Alan, and thebovus@yahoo com. "Image Quality and Radiation Dose Comparison of a Computed Radiography System and an Amorphous Silicon Flat Panel System in Paediatric Radiography: A Phantom Study." RMIT University. Applied Sciences, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091019.122013.
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This purpose of this work was to investigate the patient radiation doses and image quality of a Philips/Agfa computed radiographic (CR) system and a Philips indirect-capture digital radiographic (DR) system in a paediatric setting. A CDRAD digital radiographic contrast-detail phantom was used to assess radiographic image quality. Perspex slabs of three different thicknesses (6, 11 and 16 cm) were used to simulate paediatric patients of three arbitrary ages. These phantoms, in conjunction with the CDRAD digital radiographic contrast-detail phantom, were imaged under three different conditions. The CDRAD Analyser software package was used to assess the quality of each image. The first experiment conducted was a comparison of the two systems under standard conditions, with beam filtration of aluminium and copper, as recommended in European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Paediatrics (European Commission 1996b). Image quality was compared for each phantom size at three doses with the same entrance exposure used for both systems. A visual comparison of the resulting contrast detail curves showed the DR system generally outperformed the CR system, especially at the lowest two doses. A chi-square analysis of the targets detected generally confirmed this visual impression. The second experiment performed was to compare the two systems under the conditions used in routine clinical practice at PMH. As a result of additional beam filtration not generally being employed, the image quality of the CR system was similar to the DR system for the two smaller phantom sizes but with a major dose cost - effective doses higher by between 38% and 100%. A chi-square analysis of the targets detected showed the CR system to be significantly better than the DR system at two of three doses for the thinnest phantom and no significant difference at any doses for the intermediate phantom size. For the largest phantom size, additional filtration - although different - was used for the CR and DR systems and so the X-ray beam spectra were more similar. Consequently, the results for this phantom size reflected those from the experiment conducted under standard conditions, ie the effective doses for both systems were similar and the image quality of the DR system superior. The chi-square analysis s howed the DR system to be significantly better than the CR at all three dose levels. A third experiment was undertaken to compare doses between the two systems at 'equal' image quality. The CDRAD Analyser software specific image quality parameter, IQFinv, was held constant for both systems. The entrance exposures required to achieve this image quality were measured and then converted to effective doses using the dose calculation software package PCXMC 1.5. The DR system offered effective dose savings of between 28 and 42% for the three phantom sizes. Overall, this work suggests that a Philips flat-panel system is superior to an Agfa CR system in paediatric radiography. This result generally reflects the findings of other authors who have conducted similar studies in adult patient settings.
5
Enright, Michael Thomas. "A radiographic exposure system." Thesis, Queensland University of Technology, 1994.
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6
Polinsky, Adam S. "Evaluation and Comparison of Periapical Healing Using Periapical Films and Cone Beam Computed Tomography: Post-Treatment Follow Up." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5767.
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Purpose: The purpose of this study was to assess the radiographic changes in periapical status and analysis of healing determined using periapical radiographs (PA) versus cone beam computed tomography (CBCT) pre-operatively and at 3-64 months following endodontic treatment.
Methods: Pre/post treatment radiograph and CBCT scans of patients who had NSRCT, NSReTx, or SRCT from July 2011-December 2018 at VCU Graduate Endodontic clinic were included in this study. Volumetric and linear measurements of periapical lesions on initial and recall PA and CBCT images were performed using three calibrated examiners. Changes and differences in the estimated area from PA to CBCT were compared using the Wilcoxon signed-rank test. McNemar’s chi-squared test was used to determine agreement in the proportion of lesions that were absent (0x0) between the PA and corresponding view of CBCT. This data was used to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predicative value (NPV).
Results: A total of 51 patients with a median healing time of 13 months were included in the analysis. Significant healing was observed on both PA and CBCT images (p-value
Conclusion: Assessment using CBCT revealed a lower healing rate for all treatment categories compared with periapical radiographs. CBCT was more likely to detect the presence of a PARL, whereas a periapical radiograph would be less sensitive to detection of a PARL. Significant healing cannot be detected at an earlier point in time with PA radiographs or CBCT.
7
Pascoal, Ana Isabel Lourenco. "Optimisation of image quality and patient dose for chest radiography with digital radiographic systems." Thesis, King's College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438195.
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Haith, Misty Isanna. "Radiographic imaging of subsea pipelines." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/45436.
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Subsea pipelines are increasingly being used both around offshore drilling facilities and for long distance oil and gas transport. Accidents can have devastating environmental and economic impact, amplifying the need for accurate, reliable detection and characterisation of pipeline defects. Inspection of these pipelines for corrosion and other defects is crucial for safe operation. Radiography holds a significant advantage over many other inspection methods in that it does not require surface preparation or insulation removal. Subsea pipeline radiography is a relatively new technique, and underwater conditions are not covered by radiographic standards. Water can have a significant impact on a radiographic image and access is very difficult, meaning standardised above-water methods may not be applicable. This is particularly the case for defect characterisation; standard methods often call for calibration objects to be included in the setup, which can be a very complex operation in subsea conditions. There is also a lack of experimental data for research, due to the difficulty and high costs associated with subsea radiography. Simulation is one of the key ways of assessing inspection problems, however radiographic simulation models have not been validated for subsea inspections. This thesis addresses the two problems of accurate subsea simulation and alternative defect characterisation methods. Firstly the accuracy of a radiographic simulation model applied to subsea pipeline inspections is investigated. Experimental measurements of a sample in a water tank are used to adjust the simulation, with the aim of matching image quality parameters - such as signal-to-noise ratio and contrast. The simulation has been partially matched to experiment, with some differences found in contrast-to-noise ratio. Possible causes of the differences are analysed, with the most likely cause found to be detector backscatter and additional scatter from out-of-setup objects within the experimental exposure bay. The simulation model is then used to provide data for development and testing of a defect characterisation method. The method relies on knowledge of the setup geometry and use of multiple images, and does not require calibration objects to be included in the setup. It is specifically aimed at use in situations where access is difficult such as in subsea pipeline inspections. The method is tested on simulated and experimental flat bottomed hole defects and simulated corrosion patch defects. Results demonstrate a good, consistent ability to calculate lateral and axial defect dimensions. Defect thickness calculations are more difficult and as such errors are more significant. However, errors in thickness are due to overestimation, meaning the calculation could be used to place a maximum limit on potential defect size rather than as an actual estimate of the thickness.
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Abhishek, Abhishek. "Chondrocalcinosis : risk factors and radiographic phenotype." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12926/.
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Objectives: The objectives of this study were to a) examine the distribution of chondrocalcinosis (CC), b) determine the risk factors of CC, and c) examine the radiographic phenotype of osteoarthritis (OA) associated with CC. Methods: Data from the Genetics of Osteoarthritis and Lifestyle (GOAL) study were used to describe the radiographic distribution of CC, and to conduct a case-control study in which cases with CC were compared with controls without CC. All participants had already completed a detailed questionnaire, been examined by a research metrologist, had radiographs of knees, hands, and pelvis, and had given urine and blood samples. All radiographs had been scored for structural radiographic changes of OA, and for the presence of CC. Frontal plane knee alignment was measured on all knee radiographs. The prevalence (95% confidence interval (CI)) of CC was calculated. The odds ratio (OR) and 95% CI were calculated for risk factors of CC, and for structural changes associated with CC in joints with OA. This was adjusted for age, gender, body mass index (BMI), and OA as appropriate, using logistic regression. Results: 3170 participants were included in this study. There were 431 cases with CC. The overall prevalence (95%CI) of CC in the GOAL population was 13.7% (12.5% - 14.9%). In the GOAL population, knee was the commonest site of CC. However, 42% of participants with CC did not have any knee involvement. There was evidence for a generalized predisposition to CC. For example, CC at one joint associated with CC at distant joints. Joints with CC clustered together more than would be expected by chance alone. At knees, wrists and hips, bilateral CC was more likely to associate with CC at distant joints than unilateral CC – also supporting the existence of a systemic predisposition to CC. After adjusting for confounding factors, there was an association between CC and increasing age, lower current BMI, and OA. The association between OA at one joint and CC at the same joint was present for all joints except for the hip. There was no association between CC and gender, diuretic intake, and selected single nucleotide polymorphisms in enzymes involved in pyrophosphate (PPi) metabolism. CC associated with peri-articular calcification, vascular calcification, low cortical bone mineral density (BMD) but not with low cancellous BMD. Self-reported arthroscopy, meniscectomy, knee injury, occupational knee joint loading and knee mal-alignment in the 3rd decade of life associated with knee CC. However, after adjusting for confounding factors including OA, there was no association between either self-reported or radiographically assessed current knee mal-alignment and knee CC. In joints with OA, the additional presence of CC at the same joint associated with a different radiographic phenotype of structural arthropathy. For example, in knees with OA, knee CC associated with attrition. In hips with OA, hip CC associated negatively with osteophytes, joint space narrowing, and sclerosis at the right hip but not at the left. Similarly, in wrists with OA, wrist CC associated with sclerosis in the right but not in the left wrist; in scapho-trapezioid joints (STJs) with OA wrist CC associated with sclerosis on both sides; in metacarpophalangeal joints with OA, wrist CC associated with cysts in the right but not in the left hand; and in 1st carpometacarpal joint with OA, wrist CC associated with cysts in the left but not in the right hand. In knees with OA, the additional presence of CC at distant joints associated with knee attrition. Those with knee CC + OA were excluded from this analysis to remove any local effects of CC. CC at distant joints did not associate with a distinct structural OA phenotype in other joints examined. Conclusion: These findings suggest that CC results form a systemic predisposition, and that it commonly occurs at other joints in the absence of knee involvement. Established risk factors of CC such as age, OA, and previous arthroscopy and/or meniscectomy were validated in this study. Several novel risk factors of CC e.g. low current BMI, low cortical BMD, and vascular calcification were identified. Several novel associations of knee CC i.e. early life knee malalignment, self-reported knee injury, and occupational knee loading were also recognised. There was convincing evidence to suggest that in joints with OA, the additional presence of CC modifies the OA phenotype, and that this varies from joint to joint.
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Friedrich-Nel, Hesta. "Assessment innovation in Radiographic Pathology II." Journal for New Generation Sciences, Vol 3, Issue 2: Central University of Technology, Free State, Bloemfontein, 2005. http://hdl.handle.net/11462/478.
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Published Article<br>Innovation in teaching and learning compel facilitators to explore creative possibilities in teaching and learning. Consequently innovative assessment has replaced traditional assessment methods in the Radiographic Pathology II module. The use of an appropriate variety of assessment methods or approaches is crucial to enhance and support learning and measure performance. Thus assessment has to change from knowledge acquisition and factual recall to assess more embracing and critical learning outcomes such as problem-solving, communication, attitudes, critical thinking, professionalism and ethics. Moreover, assessment has to impact positively on learning, promote deep learning and correspond with the learning outcomes of the module. Addressing these demands in assessment, this paper presents practical examples of assessment innovation during 2004 in the Radiographic Pathology II module.
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Han, Yang. "Organ Doses in Routine Radiographic Procedures." VCU Scholars Compass, 1989. http://scholarscompass.vcu.edu/etd/5066.
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There is general agreement that the extent of the risk from x-ray examination is related in some way to the radiation dose. As the dose increases, the likelihood of significant biological effects also increases. If a clear correlation between dose and effect is to be established, a convenient and reasonably accurate method of estimating patient’s absorbed doses during common radiographic examinations will be highly needed. A simple method is developed in this project to determine the two important parameters e exposure at skin entrance (ESE) and half value layer (IIVL), which is essential to get reasonably accurate estimates of absorbed doses. Then, the patient’s absorbed doses in common x-ray examinations can be estimated using the computer program. The absorbed doses in 12 routine radiographic projections were calculated by the use of clinical data in MCV Hospital.
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Cherry, Shirley J. "Radiographic Pathology of the Skeletal System." Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etsu-works/2481.
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Bowen, Amber Jean. "Bone Density Measurement via Radiographic Calibration." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/341.
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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.
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Berenguer, Gaston. "Lamina dura bundle bone or radiographic artifact /." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010577.
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Thesis (M.S.)--University of Florida, 2005.<br>Typescript. Title from title page of source document. Document formatted into pages; contains 45 pages. Includes Vita. Includes bibliographical references.
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Ólafsson, Yngvi. "Idiopathic scoliosis : radiographic, neurophysiologic and psychologic aspects /." Reykjavik ; Stockholm : Y. Ólafsson, 1999. http://diss.kib.ki.se/1999/9979-60-506-3/.
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Verhovsek, Ester L. "Radiography Curriculum Change Update: American Society of Radiologic Technologists." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etsu-works/2591.
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Elhain, Ahmed M. S. B. "An investigation of the influence of radiographic malpositioning and image processing algorithm selection on ICU/CCU chest radiographs." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/7342.
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Mobile chest radiography remains the most appropriate test for critical care
patients with cardiorespiratory changes and with patients who have chest tubes
and lines as a monitoring tool, and to detect complications related to their use.
However, one of the most frequent issues recognized radiographically with
patients in critical care is chest tubes and lines malposition. This can be related to
technical quality reasons which can affect their appearance in the chest
radiography.
This research considers how the technical quality of the ICU/CCU chest radiography
can impact upon the appearance of chest tubes/lines and how that appearance can
impact on the decision making.
Results show that the methods used in the chest phantom experiment to estimate
the degree of angulation have a large effect upon the appearance of anatomical
structures, but it does not have a particularly large effect upon the apparent
changes of tube/line position central venous catheter and endotracheal tube (CVC,
ETT).
The study also shows that there was a little difference between the two image
processing algorithms, apart from the visualisation of sharp reproduction of the
trachea and proximal bronchi, which was significantly better using the standard
algorithm compared to the inverted algorithm.
The two methods used to estimate the degree of angulation and the apparent
position of the CVC/ETT on 17 mobile chest radiographs provide limited useful
information to the image interpreter in estimating the degree of angulation and
degree of malpositioning of the tube and line.
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Pettersson, Kurt. "Whiplash injury : a clinical, radiographic and psychological investigation." Doctoral thesis, Umeå universitet, Ortopedi, 1996. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-96904.
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Whiplash injury is a common and troublesome disorder and approximately 10-40 per cent of its victims develop chronic symptoms. The annual incidence is estimated at 1/1000 inhabitants and the prevalence at 1%. The cause of chronic symptoms after whiplash injury is still unknown and no effective treatment has been presented so far. The present study is divided into two parts; the first part includes clinical, radiographic and psychological investigations, and the second part the effect of surgical intervention as well as intervention with medication. MRI studies (n=39) showed a larger proportion of pathologic findings compared to normal subjects, but no correlation with initial neurologic deficits was found. At the 2-year follow-up all patients with disc herniations with medullary impingement had persistent symptoms. Three patients had disc herniations that deteriorated from slight and moderate initial changes on the MRI to severe changes with medullary cord impingement. This deterioration might be a first sign of disc degeneration. Thus our results indicate that disc pathology is a contributing factor in the development of chronic symptoms. Measurements from standard lateral radiographs taken in neutral position were evaluated (n=48). A graphic digitizer connected to a microcomputer was used and the sagittal diameters were determined. Multivariate analysis of variance showed that the spinal canal was significantly smaller in patients with persistent symptoms indicating that a narrow spinal canal is unfavourable in patients subjected to whiplash injury. A psychological investigation (n=70) revealed no relationship between pre-existing personality traits and persistent symptoms. In our study, whiplash patients showed no differences in personality traits compared to normal controls. Our results after discectomy and anterior cervical fusion (n=20) because of chronic symptoms after whiplash injury were not satisfactory. We noticed that about half of the cases had less headache and neck pain but no beneficial effects on radicular pain, vertigo, visual and auditory symptoms were observed. Based on the criteria of a surgical evaluation, two patients were classified as good, nine as fair and nine as poor. A prospective randomised double-blind study of high-dose methyl-prednisolone compared to placebo was conducted (n=40). A clinical follow-up with repeated neurological examinations and a standardised questionnaire including VAS-scales and a pain sketch form were used for the evaluation of initial symptoms, before drug administration and at the follow-ups at 2 weeks, 6 weeks, and 6 months after the injury. At the 6-month follow-up there was a significant difference between the actively treated patients and placebo concerning disabling symptoms defined as inability to return to previous work, number of sick-days and sick-leave profile. All the actively treated patients had returned to work and none had multiple symptoms though three of them complained of intermittent neck pain. Our conclusion is therefore that acute treatment with high-dose corticosteroids might be beneficial to the prevention of disabling symptoms after whiplash injury.<br><p>Härtill 6 uppsatser</p><br>digitalisering@umu
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Mallineni, Sreekanth Kumar. "Radiographic localization of supernumerary teeth in the maxilla." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46848940.
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Keenan, R. "Development and radiographic applications of x-ray lasers." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368599.
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Ariffin, Siti Mariam Zainal. "Radiographic and pathologic studies of feline appendicular osteoarthritis." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6188/.
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Feline Osteoarthritis (OA) is a pathological change of a diarthrodial articulation which primarily occurs in older cats. The aims of this study were:- 1) to define the radiographic features of OA in the cat for each individual appendicular joint; 2) to relate the radiographic features to the gross pathologic and histopathologic features; 3) to explore underlying causes of OA in cats, 4) to identify the presence of Protease Activated Receptor-2 (PAR-2) and matriptase in feline articular cartilage and synovial membrane and to determine their role in OA pathogenesis. The present study has defined five radiographic features of OA for each appendicular joint:- presence of osteophytes, enthesiophytes, areas of abnormal mineralisation,synovial effusion and joint remodelling. The study furthermore suggested that increases in radio-opacity beneath the semilunar notch, along the femoral trochlea, beneath the tibial plateau and on the femoral head/neck are also important radiographic features. The radiographic prevalence was highest in the elbow (23.9%, 93/389) and stifle (23.9%,93/389) joints, followed by the hip (21.1%, 82/389), tarsal (17.7%, 69/389), shoulder(6.7%, 27/389) and carpal (6.4%, 25/389) joints. The results from this study demonstrate that the presence of a radiographically apparent supinator sesamoid bone(SSB), meniscal mineralisation (MM) and two fabellae are related to cartilage pathology and can be indicators of OA. Prevalence rates for gross pathology changes were highest in the elbow (20.2%,102/506) joint, followed by the stifle (19.6%, 99/506), hip (18.4%, 93/506), shoulder (17.8%, 90/506), tarsal (15.0%, 76/506), and carpal (9.1%, 46/506) joints. Eight key gross pathologic features were identified- cartilage discolouration, cartilage fibrillation,cartilage ulceration, cartilage erosion, osteophytes, thickening of joint capsule, synovium discolouration and joint remodelling. The radiographic and gross pathologic total scores were positively correlated in each appendicular joint and the joint most likely to have cartilage damage without radiographic evidence of OA is the shoulder (71.1%, 64/90) followed by the elbow (39.1%, 9/23), hip (32.4%, 11/34), stifle (26.1%,6/23), carpal (23.1%, 21/91) and tarsal (14.9%, 7/47) joints. Four possible underlying conditions that lead to secondary OA were identified:- radioulnar incongruity, hip dysplasia (HD), cranial cruciate ligament (CCL) disease and primary meniscal mineralisation. The identification of PAR-2 and matriptase proteins and gene expression in feline articular tissues is a novel and important finding supporting the hypothesis that serine proteases are involved in the articular cartilage degradation seen in feline OA.
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Almeida, Raquel Lopes da Costa Ferreira de. "Canine hip dysplasia: radiographic evaluation of german shepherds." Master's thesis, Universidade de Évora, 2022. http://hdl.handle.net/10174/30759.
Full textAbstract:
Canine hip dysplasia is a common orthopedic disorder that affects dogs of all ages and
breeds. The exact cause and hereditability of this condition remain unclear. However,
good progress has been made in recent years. It is described as a polygenic multifactorial
condition. Different treatments are available, whether a surgical or conservative approach
is pursued.
This dissertation includes a literature review considering the topic of canine hip dysplasia
and a preliminary, exploratory study that has the objective of evaluating different
radiographic measurements and investigating their correlations and their possible value
to help diagnose and differentiate German Shepherds with or without hip dysplasia. For
this purpose, acetabular measurements were made in radiographs obtained in the standard
hip-extended ventrodorsal view.
The results suggest statistically relevant differences between dysplastic and nondysplastic
and also between male and female dogs. However, further investigation on
these measurements and their utility is warranted; RESUMO:
DISPLASIA DE ANCA EM CÃES: AVALIAÇÃO RADIOGRÁFICA DE
PASTORES ALEMÃES EM PORTUGAL
Displasia de anca em cães é um problema ortopédico comum que afeta cães de todas as
idades e raças. As causas e heritabilidade exata desta condição continuam obscura. Apesar
de se ter registado um bom progresso ultimamente. É descrita como uma doença
poligénica e multifatorial. Diferentes tratamentos médicos e cirúrgicos estão disponíveis.
Esta dissertação inclui uma revisão bibliográfica sobre displasia de anca em cães e um
estudo preliminar e exploratório que tem como objetivo avaliar diferentes medidas
radiográficas e investigar as suas correlações e o seu potencial valor para ajudar no
diagnóstico e diferenciação de Pastores Alemães com ou sem displasia. Assim, foram
realizadas diferentes medidas acetabulares foram realizadas em radiografias obtidas na
vista ventrodorsal com os membros em extensão máxima.
Os resultados sugerem diferenças estatisticamente relevantes entre cães com e sem
displasia e entre machos e fêmeas. Contudo, mais estudos sobre estas medidas e a sua
utilidade são necessários.
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Yates, Richard. "Genetic, pathologic, and radiographic correlations in multiple sclerosis." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:a2ae7907-3124-4c65-83fc-72fa00fd45ed.
Full textAbstract:
Substantial evidence suggests that cortical tissue injury plays a key role in the progression of permanent disability in multiple sclerosis (MS). A greater knowledge of factors that drive pathology in the MS cortex is therefore desperately needed in order to develop novel medicines that can ameliorate disease burden in the progressive stage. In the current thesis, we undertake a robust and quantitative analysis of motor cortical neuropathology in a large cohort of post-mortem MS cases. We find that genetic variation at the HLA-DRB1 locus is associated with the extent of cortical demyelinating and inflammatory disease, especially in younger cases. Relevant to cortical neurodegeneration, we identify fibrinogen deposition as a novel component of MS cortical pathology that associates with neuronal loss, show that carriage of HLA- DRB1*15 has a critical impact on the relationship between microglia/macrophage inflammation and cortical neuronal density, and demonstrate disease-relevant changes to motor cortical neuronal glutamic acid decarboxylase expression. Given the myriad subcortical connections of the motor cortex, we have also undertaken an extensive assessment of corticospinal tract lesional burden throughout the neuraxis and find that motor cortical neurodegeneration appears independent of subcortical tissue injury. Taken together, this thesis highlights the importance of genetic variation at the HLA- DRB1 locus to cortical pathologic outcome, and the fundamental contribution of fibrinogen deposition and cortical parenchymal inflammatory factors to neuronal fate.
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Furniss, Caryl. "Radiographic changes in Thoroughbred yearlings in South Africa." Diss., University of Pretoria, 2010. http://hdl.handle.net/2263/27207.
Full textAbstract:
A radiographic examination forms part of the pre-purchase examination of Thoroughbred yearlings at national sales in many countries. This data enables the recording of the prevalence of radiographic changes in selected Thoroughbred populations around the world and assists veterinarians in advising clients on the purchase of yearlings. This has financial implications for the client as well as the racing industry as a whole. Radiographic examinations of the 269 Thoroughbred yearlings lodged at the 2008 National Yearling Sale in Germiston, South Africa were collected and individually evaluated. The prevalence of radiographic changes was recorded and percentages calculated. These changes were compared to studies of other yearling populations. Radiographic changes present in the studied Thoroughbred population are: pedal osteitis 1.26%, metatarsophalangeal joint dorsal osteochondral fragmentation 1.60%, sagittal ridge changes 5.7%, ulnar carpal bone lucencies 8.33%, carpal osteophytes 1.19%, distal intertarsal and tarsometatarsal joint radiographic changes 9.92%, tarsal osteochondrosis lesions 4.4% and stifle joint osteochondrosis lesions 0.4%. These changes were found to be of lower prevalence when compared to similar studies. The prevalence of dorsal osteochondral fragments in the metacarpophalangeal joint was 1.60% which was similar to other studies. A higher prevalence of vascular channels was visible in the proximal sesamoid bones as well as irregular borders and lucencies. Palmar metacarpophalangeal and plantar metatarsophalangeal osteochondral fragments had a recorded prevalence of 2% and 7.10%, respectively, this prevalence being generally higher when compared to similar studies. There was an absence of palmar metacarpal disease, supracondylar lysis, proximal sesamoid bone fractures and carpal osteochondral fragmentation in the current study. Additional findings recorded in the current study were: proximal interphalangeal joint hyperextension (left front 15.13%, right front 18.91%), the solar angle (right front 2.38°, left front 2.79°), the prevalence of carpal bone one (30.95%) and carpal bone five (1.59%). The study population was limited to the radiographs lodged at the sale repository. As radiographic changes may influence sale price of the yearling, radiographs of yearlings with severe radiographic changes may not have been lodged at the repository. For these reasons the prevalence of radiographic changes recorded in the current study may not be a true reflection of the entire 2006 Thoroughbred foal crop. Further work to correlate radiographic changes to differences in management, pre-sale exercise programmes and genetics needs to be done. The effect of radiographic changes on the future performance of the Thoroughbred yearling also warrants further investigation. Copyright<br>Dissertation (MSc)--University of Pretoria, 2009.<br>Companion Animal Clinical Studies<br>unrestricted
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Ho, Danny. "CLINICAL AND RADIOGRAPHIC EVALUATION OF NOBELACTIVETM DENTAL IMPLANTS." Thesis, Faculty of Dentistry, 2010. http://hdl.handle.net/2123/7076.
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IMPALLARIA, Anna. "Radiographic imaging of chemical elements for Cultural Heritage." Doctoral thesis, Università degli studi di Ferrara, 2017. http://hdl.handle.net/11392/2487963.
Full textAbstract:
Radiographic techniques, usually, don’t give information about the chemical composition of a sample. However, thanks to the K-edge differential technique, it is possible to highlight the presence of target chemical elements with the radiography.
This technique takes advantage on the K-edge discontinuity of the X-rays mass absorption coefficient. Considering a target element and acquiring two radiographies with monochromatic beams under and over the K-edge energy, the main difference between the two images is due to the presence of the element itself.
To apply this peculiar radiographic technique, using the traditional X-ray tubes, two ways are possible:
1. Monochromatizing the beam coming out through the Bragg diffraction and acquiring the two radiographic images at the energies under and over the K-edge of the target;
2. For a target element with atomic number Z, using a set of three filters of the elements Z, Z+1 and Z-1, acquiring three different radiographies that, after the digital subtraction, would give images similar to the ones obtained with monochromatic beams.
Both the two techniques have been employed in Ferrara, giving attention to the development of portable instruments, thus to promote their application in situ. For the first, the work of the thesis has been focused on the implementation of a new goniometric set-up, in respect of the existing one, and on the alignment of all the components (X-ray tube, Bragg diffraction crystal and detectors). For the second, the research has mainly regarded the use of balanced filters on canvas mock-ups painted with cadmium, copper and cobalt based pigments and their superimposition with other ones. The filters has been tested using the radiographic scanning systems developed in Ferrara.
The new radiographic scanner for in situ application has been designed, realized and tested in the PhD period. Its reduced dimensions have allowed its use also on a big dimension painting (195 x 154 cm) in the Gallery of Palazzo Bellomo in Siracuse.<br>Tipicamente le tecniche radiografiche non permettono di ottenere informazioni riguardanti gli elementi chimici presenti in un campione. Tuttavia, grazie alla tecnica differenziale al K-edge, anche tramite la radiografia è possibile evidenziare la presenza di elementi chimici bersaglio.
La tecnica sfrutta la discontinuità del K-edge nel coefficiente di assorbimento di massa dei raggi X. Considerando un elemento target e acquisendo due radiografie con fasci monocromatici di energia sotto e sopra il K-edge, la maggiore differenza tra le due immagini sarà dovuta alla presenza dell’elemento stesso.
Per effettuare questa particolare tecnica radiografica, sfruttando i classici tubi a raggi X, si possono percorrere due vie:
1. monocromatizzare il fascio uscente tramite diffrazione di Bragg e acquisire le due immagini radiografiche alle energie sopra e sotto il K-edge del target;
2. per un elemento bersaglio di numero atomico Z, usare un set di tre filtri degli elementi Z, Z+1 e Z-1, acquisendo tre radiografie diverse che, dopo sottrazione digitale, daranno immagini simili a quelle ottenute con i fasci monocromatici.
Entrambe le tecniche sono state impiegate a Ferrara, ponendo particolare attenzione allo sviluppo di strumenti portatili, così da favorirne la loro applicazione in situ. Per la prima, il lavoro di tesi si è concentrato sull’implementazione di un sistema goniometrico rispetto a quello esistente e sull’allineamento di tutte le sue parti (tubo a raggi X, cristallo per la diffrazione di Bragg e rivelatori). Per la seconda, la ricerca ha riguardato maggiormente l’applicazione dei filtri bilanciati a provini su tela di pigmenti a base di cadmio, rame e cobalto e della loro sovrapposizione con altri pigmenti. I filtri sono stati testati impiegando i sistemi a scansione per le radiografie sviluppati a Ferrara.
Il nuovo scanner radiografico per le applicazioni in situ è stato progettato, realizzato e testato durante questo lavoro di tesi. Le sue ridotte dimensioni, ne hanno consentito l’applicazione anche su un dipinto di grandi dimensioni (195 x 154 cm) nella Galleria di Palazzo Bellomo di Siracusa.
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Månsson, Lars Gunnar. "Evaluation of radiographic procedures investigations related to chest imaging /." Göteborg, Sweden : Dept. of Radiation Physics, Göteborg University, 1994. http://catalog.hathitrust.org/api/volumes/oclc/35482139.html.
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Soikkonen, K. (Kari). "Radiographic oral findings and death risk in the elderly." Doctoral thesis, University of Oulu, 1999. http://urn.fi/urn:isbn:9514254546.
Full textAbstract:
Abstract
Radiographic oral and maxillofacial findings were
recorded in a cohort of 293 home living elderly, in Helsinki, Finland,
derived from a random sample of 8035 subjects, , born in 1904, 1909, and
1912, who participated in the Helsinki Ageing Study. They were 76,
81, and 86 years old at the commencement of the radiographic study.
The relationships of potentially infectious findings with increased
all-cause mortality over four years were studied. During the four-year
follow-up, 18.5% of the subjects died.
Of the 124 edentulous subjects, 17% had condylar
findings, 13% radiopaque intraosseous findings, 9% retained
roots, 6% maxillary sinus findings, 4% impacted
teeth and 3% radiolucent findings. Edentulous women had
more arthrotic condylar findings than men.
The mean number of teeth in the 169 dentate subjects was 13.9,
15.5 in men and 13.2 in women. Carious teeth were found in 75%,
radiolucent findings in 41%, teeth with vertical infrabony
pockets in 51%, furcation lesions in 28%, calculus
in 40%, and condylar findings in 25%. Periodontal attachment
loss was slight in 18%, moderate in 31%, and advanced
in 46%. 21% of the teeth had been endodontically
treated. Periapical lesions were found in 17% of these
teeth, and in 4% of the other teeth. 75% of the
rootfillings were inadequate, exhibiting periapical lesions twice
as often as the adequate ones. Men had more carious teeth, periapical
lesions and furcation lesions than women, indicating better oral
hygiene and/or utilisation of dental services in women.
Compared with the previous studies carried out in Finland,
slightly more teeth and less tooth-associated pathology were found
in the present subjects. In contemporary Scandinavian studies, only a
slightly better oral health status in the elderly has been reported.
During the four-year follow-up, mortality was higher in the
subjects with moderate to advanced infrabony pockets, OR 2.2, 1.0-4.7.
In the previous studies, similar associations have been found in larger
study cohorts including younger subjects. Our results indicate that
oral foci may be more dangerous for the elderly than it has been
previously thought, as the subjects who died had poorer dental health
than those who survived.
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Sagerfors, Marcus. "Total wrist arthroplasty : A clinical, radiographic and biomechanical investigation." Doctoral thesis, Örebro universitet, Institutionen för medicinska vetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-50040.
Full textAbstract:
Aim: To study patient-related functional outcome measures, implant survival and radiographic loosening after total wrist arthroplasty (TWA) using four different implants. To evaluate a new TWA design biomechanically and clinically. Methods: The studies included two cohort studies with prospectively collected data (n=206 and n=219), an anatomic and kinematic analysis in a cadaveric model and a pilot study (n=20). Results: The Maestro TWA had a significantly greater improvement of radial/ulnar deviation than the Biax and Remotion TWAs. Summarized patientrelated functional outcome was significantly better for the Maestro than for the Remotion TWA. Cumulative implant survival after 8 years was 94% for Remotion, and 95% for Maestro implants. Radiographic loosening five years postoperatively was present in 26% of the Biax wrists, 18% of those with Remotion, and 2% of those with Maestro. Following TWA with the new implant design in a cadaveric model, there were no statistically significant changes compared to a native wrist regarding flexion, extension, radial deviation, the extension/radial deviation component of the dart-thrower’s motion, or the circumduction range of motion. Clinically, there was significant improvement of COPM, PRWE and VAS pain scores. Wrist extension and ulnar deviation improved, while grip strength remained largely unchanged. Conclusions: TWA is a surgical procedure which may offer a high level of patient satisfaction. Implant design may affect patient-related functional outcome after TWA. Implant survival as well as the frequency of radiographic loosening differed considerably between the four types of implants and might be a result of different implant design. Kinematic analysis of the new TWA design suggests that a stable and functional wrist is achievable with this design. Surgical placement of the new total wrist implant was reproducible and the implant yielded good patient-related outcome measures in the short term. Since TWA is an evolving procedure, further studies are warranted in order to refine indications and the place for TWA in modern hand surgery.
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Norrman, Eva. "Optimisation of radiographic imaging by means of factorial experiments /." Örebro : Örebro universitetsbibliotek, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-1731.
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Shao, Hua. "Scintillating fiber optics and their application in radiographic systems /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487777170404818.
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Sundén, Pikner Solweig. "Radiographic follow-up analysis of Brånemark® dental implants /." Göteborg : Department of Oral and Maxillofacial Radiology, Institute of Odontology, University of Gothenburg, Folktandvården, Postgraduate Dental Education Center, 2008. http://hdl.handle.net/2077/10124.
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Evanoff, Michael Geoffrey 1964. "Automatic identification of chest orientation in digital radiographic images." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282811.
Full textAbstract:
Radiology departments are implementing conversion from the use of hard copy film in favor of digital imaging. New digital acquisitions are increasing the efficacy of radiological imaging. The outputs of new modalities such as magnetic resonance (MR) and computed tomography (CT) are digital. They both involve gathering information that allows reconstructing cross sectional projections of internal structures and displaying them as digital images. Other technologies, e.g., computed radiography (CR), can provide digital radiographic data that replaces analog projection radiography. To date, the processed digital data is still transferred to film to provide a typical radiographic film in appearance. The film is presented to the doctor for diagnostic review. The research in this dissertation is concerned with making a film-less department. It specifically addresses problems in presenting CR images to the physician. The goal of this research is to create a computer recognition algorithm that will automatically recognize the orientation and discriminate between the lateral and posteroanterior view of digital chest radiographs image. The algorithm maintains 91.9% accuracy rate. The recognition takes .15 second per image.
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Pourchot, Aloïs. "Improving Radiographic Diagnosis with Deep Learning in Clinical Settings." Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS421.
Full textAbstract:
Les succès impressionnants de l'apprentissage profond au cours de la dernière décennie ont renforcé son statut de norme pour résoudre les problèmes difficiles d'apprentissage automatique, et ont permis sa diffusion rapide dans de nombreux domaines d'application. L'un de ces domaines, qui est au cœur de ce doctorat, est l'imagerie médicale. L'apprentissage profond a fait de la perspective exaltante de soulager les experts médicaux d'une fraction de leur charge de travail grâce au diagnostic automatisé une réalité. Au cours de cette thèse, nous avons été amenés à considérer deux problèmes médicaux : la tâche de détection des fractures, et la tâche d'évaluation de l'âge osseux. Pour chacune de ces deux tâches, nous avons cherché à explorer les possibilités d'amélioration des outils d'apprentissage profond visant à faciliter leur diagnostic. Avec cet objectif en tête, nous avons exploré deux stratégies différentes. La première, ambitieuse mais arrogante, nous a conduit à étudier le paradigme de la recherche d'architecture neuronale, une succession logique de l'apprentissage profond qui vise à apprendre la structure même du modèle de réseau neuronal utilisé pour résoudre une tâche. Dans une seconde stratégie, plus simple mais aussi plus sage, nous avons tenté d'améliorer un modèle par l'analyse méticuleuse des sources de données à disposition. Dans les deux cas, un soin particulier a été apporté à la pertinence clinique de nos différentes contributions, car nous pensons que l'ancrage pratique de nos différents résultats est tout aussi important que leur obtention théorique<br>The impressive successes of deep learning over the course of the past decade have reinforced its establishment as the standard modus operandi to solve difficult machine learning problems, as well as enabled its swift spread to manifold domains of application. One such domain, which is at the heart of this PhD, is medical imaging. Deep learning has made the thrilling perspective of relieving medical experts from a fraction of their burden through automated diagnosis a reality. Over the course of this thesis, we were led to consider two medical problems: the task of fracture detection, and the task of bone age assessment. For both of them, we strove to explore possibilities to improve deep learning tools aimed at facilitating their diagnosis. With this objective in mind, we have explored two different strategies. The first one, ambitious yet arrogant, has led us to investigate the paradigm of neural architecture search, a logical succession to deep learning which aims at learning the very structure of the neural network model used to solve a task. In a second, bleaker but wiser strategy, we have tried to improve a model through the meticulous analysis of the data sources at hands. In both scenarios, a particular care was given to the clinical relevance of our different results and contributions, as we believed that the practical anchoring of our different contrivances was just as important as their theoretical design
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Sadan, Madeh Adel Abd Elrahiem. "Radiographic studies on the carpal joints in some small animals." Giessen VVB Laufersweiler, 2010. http://geb.uni-giessen.de/geb/volltexte/2010/7619/index.html.
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Cruickshank, John Johnston. "Morphometric and radiographic characterization of leg disorders in broiler chickens." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24601.
Full textAbstract:
The objective of this study was to investigate the effects of cage density and excess vitamin D₃ on the incidence and severity of leg abnormalities in broiler chickens. In addition, sequential morphometric and radiographic
characteristics of leg bone development were described in normal and abnormal broilers in an attempt to develop a pattern recognition for leg abnormalities in poultry.
Twisted leg, characterized by a progressive medial (varus) or lateral (valgus) deviation of the distal tibiae was the predominant leg abnormality observed. Lateral deviations were more common than medial deviations (92% and 8%, repectively) and it occurred equally on the right and left leg. The incidence of twisted leg was considerably higher in cages than on litter (21% vs 4%, respectively).
High density and excess dietary vitamin D₃ resulted in a significant increase in the incidence of twisted leg. Differences in incidence could not be explained through differences in body weight or feed consumption. However, broilers fed the excess vitamin D₃ consumed more but gained less body weight, suggesting a metabolic stress may have been involved. High density appeared to increase the severity of the disorders, while excess vitamin D₃ had no effect on severity. Morphometric and radiographic comparisons of tibiae from normal broilers and those with twisted leg suggested that the development of twisted leg may be related to a structural abnormality in the distal tibiae; namely shallow distal condyle grooves. Changes in tibiae morphology associated with the progression of the disorder appeared as functional adaptations to the deformation rather than the primary cause of the bone deviations themselves.
Sequential radiography of tibae from clinically normal broilers revealed a high incidence of tibial dyschondro-plasia in the proximal metaphyses at 3, 4 and 5 weeks (60%, 20% and 20%, respectively). It was concluded that tibial dyschondroplasia may be more common than it is realized.<br>Land and Food Systems, Faculty of<br>Graduate
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麥淑嫻 and Suk-han Anna Mak. "Thumb base joints: comparison between standard and special radiographic projections." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31223187.
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Colorado, Claudia. "Clinical and Radiographic Evaluation of MTA Pulpotomies: A Retrospective Study." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3438.
Full textAbstract:
Vital pulp therapy is the group of procedures indicated to maintain pulp vitality allowing for continued root development and apical closure in the presence of pulp exposure due to caries or trauma. Complete maturation results in stronger tooth structure that is more able to withstand occlusal forces. Historically, calcium hydroxide (Ca(OH)2) was the material of choice for a vital pulpotomy. Recently mineral trioxide aggregate (MTA) has been used as a pulp sealing material because of its biocompatibility and its ability to induce hard tissue barrier formation. The purpose of this retrospective study was to evaluate the clinical and radiographic outcome of vital pulp therapy procedures performed with MTA. All patients receiving MTA pulpotomies and MTA pulp caps at Virginia Commonwealth University School of Dentistry Graduate Endodontic Practice between November 30, 2009 and August 15, 2013 were recalled and evaluated for presence or absence of clinical symptoms, pulp vitality, radiographic evaluation of continued root development, dentin bridge formation or pulp canal obliteration. Results were analyzed descriptively. At time of treatment caries was found to be the most common etiologic factor. Fifty-seven percent of cases were symptomatic at time of treatment (43% asymptomatic). Forty-seven percent of the teeth presented with immature apices (53% with radiographically closed apices). Overall recall rate was 50%. At recall all teeth were clinically asymptomatic. Forty seven percent of teeth tested normally to cold (33% were non-responsive to cold) at recall. Pulp canal obliteration was seen in 6 cases, 4 molars and 2 anterior teeth. In conclusion, MTA pulpotomy and MTA direct pulp caps are a predictable treatment modality for young vital permanent teeth affected by caries or trauma.
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Hall, Nathan E. "A Radiographic Analysis of Variance in Lower Incisor Enamel Thickness." VCU Scholars Compass, 2005. http://scholarscompass.vcu.edu/etd/887.
Full textAbstract:
The purpose of this study was to help predict the enamel thickness of mandibular incisors. At least two direct digital periapical radiographs were made for each of the 80 subjects. Radiographs were scaled to control for magnification errors using dental study models and computer software. Mesiodistal incisor width and mesial and distal enamel thicknesses were measured. Lateral incisors were determined to be wider than central incisors and distal enamel thicknesses were larger than mesial enamel thicknesses on average. The African American group demonstrated wider incisors and enamel thicknesses than the Caucasian group on average. Enamel thickness positively correlated with tooth width for all incisors. No statistically significant differences were detected between male and female groups. Some conclusions relating to enamel thickness can be made based on race, incisor position, and incisor width, but correlations were not considered strong enough to accurately determine enamel width, without the aid of radiographs.
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Schmick, Aaron T. "Vital Pulp Therapy Survivability Based on Radiographic Depth of Caries." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4107.
Full textAbstract:
Purpose: The purpose of this retrospective chart review was to determine if the survival of two methods of vital pulp therapy (VPT) were influenced by the pre-operative radiographic depth and location of caries. Methods: Electronic patient records (axiUm®) that contained the procedure codes D3120, Indirect Pulp Therapy (IPT), or D3220, Therapeutic Pulpotomy (TP), were queried. Qualifying charts’ pre-operative and post-operative radiographs were viewed in MiPACS® by two raters. Visit records were queried again to identify any other treatment failures. Results: A total of 568 primary molars met the eligibility criteria. There was a difference in survival depending upon the treatment procedure (P < .0001), with D3220 having a significantly higher failure rate than D3120. In the 182 total cases with caries 2/3 to encroaching the pulp, therapy success was greater with IPT (P < .0001). Conclusion: IPT results in longer overall clinical success even at the deepest level of caries.
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Mak, Suk-han Anna. "Thumb base joints : comparison between standard and special radiographic projections /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22079142.
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Pitcher, Christopher D. "Quantitative metrics to evaluate image quality for computed radiographic images." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0007362.
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Harrison, David A. "Head Positioning And Its Relation To Radiographic Cephalometric Projection Errors." Thesis, Faculty of Dentistry, 1995. http://hdl.handle.net/2123/5053.
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Gunes, E. evren. "Computerized Test Procedure For Industrial Radiographic Examination Of Metallic Welded Joints." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605553/index.pdf.
Full textAbstract:
Radiography is an extensively used NDT method, especially in nuclear, aerospace and automotive industries where optimal designs call for greater reliability. The rules corresponding to industrial radiography are defined in a system of radiographic standards. The standards related to the radiographic testing of metallic welded joints had been harmonised in all over the Europe and at the end in 1997, the standard "<br>EN 1435"<br>was established and published. Since then, this standard has become the most widely used standard where the radiographic applications are necessary. To eliminate the person based errors during application of the standard, moreover to save time, cost and effort in radiographic exposures, in this study it was aimed to write a computer program which is able to calculate all necessary parameters for a radiographic exposure related to this standard EN 1435.
In the programming stage, Visual Basic 6.0 &<br>#61651<br>was used. The program consists of many windows, each giving and controlling separate parameters related to the exposure. Besides giving all the needed parameters, the evolved program is able to prepare a report with these parameters. So, both radiography technicians and experts can use it. It is believed that this study constructs a basis for developing other computerised test procedures for any kind of non-destructive testing methods used in industry today.
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Ivanauskaitė, Deimantė. "Alveolar bone loss in radiographic modalities for diagnosis of periodontal disease." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110621_164329-13939.
Full textAbstract:
Radiographic modalities are used in addition to clinical methods to gain information about the patients. In the examination of the periodontium, which is comprised of the gingiva, alveolar bone, periodontal ligament, and cementum, the radiographic examination plays an integral role for diagnosis of periodontal disease. The diagnosis periodontitis is based on a finding of alveolar bone loss. Changes of the alveolar bone can be assessed by different radiographic modalities, such as intraoral radiography (bitewing and periapical radiography) and panoramic radiography. Analysis of alveolar bone loss (alveolar bone level, detection of vertical bone defect and furcation involvement) in radiographic modalities and a systematic review could be helpful to suggest the more applicable radiographic methods for diagnosis of periodontal disease. The purpose of the present study was to examine diagnostic properties of panoramic radiography for the assessment of alveolar bone loss for the diagnosis of periodontal diseases as compare to posterior bitewing radiography. For 96 patients panoramic and posterior bitewing radiographs were performed and results of analysis of visibility of radiographic images and assessment of alveolar bone loss were compared. Also, the systematic review on diagnostic properties of panoramic radiography in the assessment of alveolar bone loss was performed. Based on the results of this study, recommendations for clinical practice and for research were proposed.<br>Rentgeniniai tyrimo metodai taikomi, kad būtų papildyti klinikinio tyrimo duomenys. Tiriant periodontą, kurį sudaro dantenos, dantinė atauga, periodonto raiščiai ir cementas, rentgeninis tyrimas svarbus diagnozuojant periodonto ligas, nes jo metu nustatomi dantinės ataugos pokyčiai. Dantinės ataugos pokyčiams vertinti daromos rentgeno nuotraukos taikant vidinių burnos rentgeno nuotraukų darymo metodus, t. y. kandimo ar dantų šaknų rentgeno nuotraukų darymo metodus, ir išorinės burnos rentgeno nuotraukos darymo metodą, t. y. panoraminės rentgeno nuotraukos darymo metodą. Atlikus dantinės ataugos pokyčių (kaulo lygio arba rezorbcijos, kaulo defekto ir tarpšaknio kaulo pažeidimų) analizę, taikant rentgeninius metodus, ir padarius sisteminę literatūros apžvalgą, galima būtų pasiūlyti tinkamiausią rentgeno metodą periodonto ligoms diagnozuoti.
Šio darbo tikslas – ištirti ir palyginti panoraminės rentgeno nuotraukos ir kaplių bei krūminių dantų rentgeno nuotraukų darymo metodų diagnostikos ypatybes vertinant dantinės ataugos pokyčius periodonto ligoms diagnozuoti.
Kiekvienam, iš 96 pacientų įtrauktų į tyrimą, buvo padaryta panoraminė rentgeno nuotrauka ir kaplių bei krūminių dantų kandimo rentgeno nuotraukos. Atlikta dantinės ataugos rentgeno atvaizdo vizualioji kokybė analizė ir vertinimai skirtingose rentgeno nuotraukose bei palyginti rezultatai. Padaryta sisteminė literatūros apžvalga apie panoraminės rentgeno nuotraukos vertę diagnozuojant periodonto ligas.
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Saunders, Andrea J. "An evaluation of radiographic screening for tuberculosis in immigrants to Canada /." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79120.
Full textAbstract:
Introduction. Foreign-born persons applying for permanent residence in Canada must undergo radiographic screening for tuberculosis (TB). As a screening tool for TB, however, the chest x-ray has a number of limitations.<br>Objectives. To evaluate the reliability of chest radiographic screening as well as its ability to detect prevalent active TB and predict future incident disease in immigrants to Canada.<br>Methods. Immigration screening x-rays were categorized by 12 physicians experienced in TB; observer agreement was calculated using the kappa coefficient. The prevalence and incidence of active TB diagnosed among applications screened at the Montreal Chest Institute between 1995 and 1998 was measured.<br>Results. Intra- and inter-observer agreement was fair to moderate. Among 36,433 applicants screened, 53 prevalent cases were detected (0.145%) and 19 incident cases were reported post-screening (25.7 per 100,000 person-years).<br>Conclusion. Radiographic screening successfully detects immigrants with active TB but is limited in preventing future incident cases. Observer agreement needs to be improved.
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Offiah, Amaka. "Optimisation of the digital radiographic imaging of suspected non-accidental injury." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1444875/.
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Aim: To optimise the digital (radiographic) imaging of children presenting with suspected non-accidental injury (NAI).;Objectives: (i) To evaluate existing radiographic quality criteria, and to develop a more suitable system if these are found to be inapplicable to skeletal surveys obtained in suspected NAI. (ii) To document differences in image quality between conventional film-screen and the recently installed Fuji5000R computed radiography (CR) system at Great Ormond Street Hospital for Children, (iii) To document the extent of variability in the standard of skeletal surveys obtained in the UK for suspected NAI. (iv) To determine those radiographic parameters which yield the highest diagnostic accuracy, while still maintaining acceptable radiation dose to the child, (v) To determine how varying degrees of edge-enhancement affect diagnostic accuracy. (vi) To establish the accuracy of soft compared to hard copy interpretation of images in suspected NAI.;Materials and Methods: (i) and (ii) Retrospective analysis of 286 paediatric lateral spine radiographs by two observers based on the Commission of European Communities (CEC) quality criteria, (iii) Review of the skeletal surveys of 50 consecutive infants referred from hospitals throughout the United Kingdom (UK) with suspected NAI. (iv) Phantom studies. Leeds TO. 10 and TO. 16 test objects were used to compare the relationship between film density, exposure parameters and visualisation of object details, (iv) Clinical study. Anteroposterior and lateral post mortem skull radiographs of six consecutive infants were obtained at various exposures. Six observers independently scored the images based on visualisation of five criteria, (v) and (vi) A study of diagnostic accuracy in which six observers independently interpreted 50 radiographs from printed copies (with varying degrees of edge-enhancement) and from a monitor.;Results: The CEC criteria are useful for optimisation of imaging parameters and allow the detection of differences in quality of film-screen and digital images. There is much variability in the quality and number of radiographs performed as part of skeletal surveys in the UK for suspected NAI. The Leeds test objects are either not sensitive enough (TO. 10) or perhaps over sensitive (TO. 16) for the purposes of this project. Furthermore, the minimum spatial resolution required for digital imaging in NAI has not been established. Therefore the objective interpretation of phantom studies is difficult. There is scope for reduction of radiation dose to children with no effect on image quality. Diagnostic accuracy (fracture detection) in suspected NAI is generally low, and is not affected by image display modality.;Conclusions: The CEC quality criteria are not applicable to the assessment of clinical image quality. A national protocol for skeletal surveys in NAI is required. Dedicated training, close supervision, collaboration and consistent exposure of radiologists to cases of NAI should improve diagnostic accuracy. The potential exists for dose reduction when performing skeletal surveys in children and infants with suspected NAI. Future studies should address this issue.
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Li, Ru. "Distraction osteogenesis in adolescents and adults : influencing factors and radiographic classification." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444245.
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Messent, Elizabeth Ann. "Quantitative radiographic assessment of tibial cancellous bone changes in knee osteoarthritis." Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407638.
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Hackman, S. Lucina M. R. "Age estimation in the living : a test of 6 radiographic methods." Thesis, University of Dundee, 2012. https://discovery.dundee.ac.uk/en/studentTheses/b8281974-f44c-444d-b958-001ccfea451f.
Full textAbstract:
There is a growing recognition that there is a requirement for methods of age estimation of the living to be rigorously tested to ensure that they are accurate, reliable and valid for use in forensic and humanitarian age estimation. The necessity for accurate and reliable methods of age estimation are driven both by humanitarian, political and judicial need. Age estimation methods commonly in use today are based on the application of reference standards, known as atlases, which were developed using data collected from children who participated in longitudinal studies in the early to mid-1900s. The standards were originally developed to provide a baseline to which radiographs could be compared in order to assess the child’s stage of skeletal development in relation to their chronological age, a purpose for which they are still utilised in the medical community. These atlases provide a testable link between skeletal age and chronological age which has been recognised by forensic practitioners who have essentially hijacked this medical capability and applied it to their fields. This has resulted in an increased use of these standards as a method of predicting the chronological age from the skeletal age of a child when the former is unknown. This novel use of the atlases on populations who are distinct, ethnically, temporally and geographically, from those whose data was gathered and was used in the design of the standard leaves the forensic outcomes vulnerable to challenge in court. This study aims to examine the reliability and accuracy of these standards in relation to a modern population, providing a sound statistical base for the use of these standards for forensic purposes. Radiographs were collected from the local hospital from children who had been X-rayed for investigation during attendance at the local A&E department. Four body areas were selected for investigation; the hand-wrist, the elbow, the knee and the foot-ankle and tests were undertaken to assess the radiographs using six commonly uses methods of age estimation. Further images of the wrist and elbow were collected from children in New Delhi, India. These images were subject to age estimation utilising the methods described.