Dissertations / Theses: 'Radiography'

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Davidson, Robert Andrew. "Radiographic contrast-enhancement masks in digital radiography." Thesis, The University of Sydney, 2006. http://hdl.handle.net/2123/1932.

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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.

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2

Davidson, Robert Andrew. "Radiographic contrast-enhancement masks in digital radiography." University of Sydney, 2006. http://hdl.handle.net/2123/1932.

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Doctor of Philosophy
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.

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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.

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Jackson, Marcus Thomas. "Conceptualising radiography knowledge and the role of radiography educators : perspectives and experiences of a radiography education community." Thesis, Kingston University, 2013. http://eprints.kingston.ac.uk/27737/.

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The diagnostic radiography curriculum and the process of its enactment are under researched in the United Kingdom. To date, there have been no published studies which have investigated the curriculum and the role of radiography educators from the multiple perspectives of radiography students, university radiography educators and clinical radiography educators, that is, a radiography education community. Accordingly, this study describes the perceptions and experiences of a radiography education community in relation to three research questions: 1. How does a radiography education community conceptualise the radiography knowledge and skills required of a diagnostic radiographer? 2. How does a radiography education community conceptualise the role played by university based and clinically based radiography educators in helping the radiography student acquire radiography knowledge and skills? 3. How does the community in this study compare with Lave and Wenger’s theoretical constructs of a situated learning, legitimate peripheral participation and Communities of Practice (CoP)? The epistemological foundation of the study is constructivism and the overarching methodology is a case study conducted within a single higher education institution and three of its associated clinical practice partner settings. The primary data collecting method comprised semi-structured interviews, supplemented by a critical review of germane literatures, government policy and the curriculum guidance provided by the relevant professional and statutory bodies. The theoretical framework in which the study is situated is based upon Lave and Wenger’s theories of situated learning, legitimate peripheral participation and communities of practice. The findings of the study reveal a radiography education community which is lacking any unifying pedagogic discourse. In particular, there is an absence of opportunities for cross-community working, especially in collaborative curriculum development and the process of its enactment. This is further compounded by the community’s narrow interpretation of what a curriculum should comprise. Currently there is a clear focus on knowledge content and curriculum as a product which fails to take into account praxis and the social context in which learning takes place. These findings have been summarised by a representation of the enacted curriculum as compared with the ‘ideological’ function of a radiography curriculum. Specific developments required of the curriculum include: (i) placing a greater emphasise on the vocational relevance of radiography knowledge; (ii) gaining a better understanding of tacit radiography knowledge; (iii) ensuring greater familiarity with the curriculum and (iv) enhancing the standard of clinical supervision. The radiography education community in this study evidences both convergence and divergence with Lave and Wenger’s theoretical constructs of situated learning, legitimate peripheral participation and community of practice. Within the context of radiography education the study also highlights the consequence of power relationships, the complexity of learning in and across multiple communities of practice and the importance of individual learner biographies, all of which are underdeveloped in Lave and Wenger’s theoretical discourse. These findings have been summarised in a proposed theoretical model for a radiography education community of practice. Three specific pedagogic and managerial inferences may be drawn from this study which will require staff development and consideration of how the diagnostic radiography programme is managed across the community. Firstly, context, process and praxis need to be carefully considered in the collaborative development, design and implementation of the curriculum. Secondly, the university and clinical educators need to reflect on their own learning and teaching skills by engaging more fully with pedagogy. Thirdly, communication across the radiography education community of practice must be improved.

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Grantham, Stephen Gary. "Digital speckle radiography." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619648.

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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.

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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.

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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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Tomko, Craig. "Studies in Dental Radiography." Thesis, Faculty of Dentistry, 1985. http://hdl.handle.net/2123/4278.

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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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Orafi, Ibtesam. "Aspects of radiography in endodontics." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506238.

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In this thesis, the use of radiography in endodontic practice and the importance of radiographic interpretation of periapical lesion, file and working length, and the second mesio-buccal canal (MB2) of maxillary first molar were studied. The aims of the questionnaire study were primarily to evaluate the opinions and attitudes of general dental practitioners (GDPs) and endodontists in the UK towards the use of radiography and radiographic equipments in endodontic practice. The second aim was to investigate the ability of endodontists and GDPs to interpret early apical pathology. The impact of viewing conditions on the interpretation of file and working length study was conducted to determine whether or not ideal viewing conditions have any influence on the diagnostic accuracy of observers. Finally, the effects of horizontal angulation on the interpretation of MB2 canal in maxillary first molar study was conducted in a comparison of three imaging modalities in terms of sensitivity and specificity to determine the optimal horizontal beam angulation and radiographic system for the detection of MB2 canal. Conclusions: Certain radiographic techniques highlighted by the National Endodontic Guidelines and the Faculty of General Dental Practitioners have been adopted by both specialists and GDPs in the UK. However, endodontists were more able than GDPs to recognise an early apical lesion. Furthermore, optimal viewing condition for endodontic working length requires the use of a viewing box, masking and magnification. Finally, a +20o horizontal beam angulation was found to be optimal in the identification of MB2 canal of maxillary first molar with all imaging modalities.

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Klein, Dennis William. "Low fluence neutron radiography techniques." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42613.

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Venter, Dalene. "Three-dimensional thinking in radiography." Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/1564.

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Dissertation submitted in fulfilment of the requirements for the degree Master of Technology: Radiography in the Faculty of Health and Wellness Sciences, 2008
Introduction Research to date has not been able to agree whether spatial abilities can be developed by practice. According to some researchers spatial ability is an inherited cognitive ability, compared to spatial skills that are task specific and can be acquired through formal training. It is commonly assumed that radiographers require general cognitive spatial abilities to interpret complex radiographic images. This research was conducted to investigate second year radiography students’ three-dimensional thinking skills pertaining to film-viewing assessments. Materials and methods The experimental research strategy was mainly applied together with correlation research. Two trials were run (in 2005 and 2006). The sample group consisted of fifteen second year diagnostic radiography students in 2005 and twenty-three second year diagnostic radiography students, of the same institution, in 2006. Each year group was randomly divided into a control group and an intervention group. Two instruments were used, that is a film-viewing assessment and a three-dimensional test, Academic Aptitude Test (University) (AAT) nr. nine: Spatial Perception (3-D). The whole class completed this basic spatial aptitude test, as well as a base-line film viewing assessment, which focused on the evaluation of technique/anatomy of second year specialised radiographic projections. The marks that the students achieved in the fore-mentioned tests were compared, to determine if there was any correlation between their performances in the different tests. A curricular intervention, which was intended to improve applied three-dimensional skills, was subsequently applied. The students executed certain modified radiographic projections on parts of a human skeleton. For each radiographic projection, the students had to draw the relation of the X-ray beam to the specific anatomical structures, as well as the relation of these structures to the film. The related images of these projections were also drawn. With each of the following sessions, films including images of the previous session were discussed with each student. After the intervention, the whole class wrote a second film-viewing assessment. The marks achieved in this assessment were compared to the marks of the initial film-viewing assessment to determine the influence of the intervention on the performance of the intervention group. Following this assessment, for ethical reasons, the same intervention took place with the control group. A third film-viewing assessment was then written by all the diagnostic second year students to evaluate the overall impact of the intervention on the applied three-dimensional skills of the class. The marks of both the 2005 and 2006 classes (intervention classes) were compared to the marks achieved by former classes from 2000 to 2004 (control classes), in film-viewing assessments to evaluate the role of the curricular intervention over the years. The students again completed the three-dimensional test, Spatial Perception (3-D) to evaluate the impact of the intervention on students’ general three-dimensional cognitive abilities. These marks were also compared to the marks of the third filmviewing assessment, to determine if there was any correlation between the students’ performances in the different tests. Results The intervention groups did not perform significantly better in film-viewing assessments after the intervention, compared to the control groups, but reasonable differences, favouring the intervention group, were achieved. Statistical significance was achieved in film-viewing assessments with both year groups after the whole class had the intervention. The intervention year groups also performed significantly better than the previous year groups (without the intervention) in film-viewing assessments. The performance in general three-dimensional cognitive abilities of the group of 2006 improved significantly after the intervention, but on the contrary, the performance of the group of 2005 declined. There was a small intervention effect on the performance of the group of 2006. Only a weak to moderate correlation between the marks of the students achieved in the three-dimensional tests and the marks achieved in the film-viewing assessments, was found. Conclusion The contrasting evidence between the data of the two groups (2005 and 2006) in the three-dimensional tests and the small intervention effect on the performance of the group of 2006, makes the intervention not applicable for the increase of general spatial abilities. The results of this research show that the applied three-dimensional skills of radiography students in interpreting specialised and modified projections can be improved by intensive practice, independent of their inherited spatial abilities.

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Packer, McKay Barlow. "Comparison of treatment planning decisions when combining CBCT and digital radiography verses digital radiography alone." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4140.

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Cone beam computed tomography (CBCT) is the recommended imaging modality of choice for evaluating previous endodontic treatment (1). The aim of this study was to compare treatment planning decisions made when evaluating previous endodontic treatment to determine if treatment planned and projected prognosis differs when digital radiography is used alone or in combination with CBCT. A retrospective chart review was conducted. Patients for whom a CBCT was taken were included in the study. Twenty-eight patients qualified. Patient’s periapical digital radiographs (Dexis©) were evaluated by 2 calibrated endodontists, a treatment plan was identified and a prognosis was projected. Later the same radiographs were viewed with CBCT scan. The CBCT provided significant information 75% of the time. CBCT provided the only information for an accurate diagnosis 17% of the time. Prognosis changed 38% of the time when CBCT was added. An unfavorable or questionable prognosis changed to favorable 30% of the time.

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Johnson, Kennita A. "Quantifying computed radiography (CR) and digital radiography (DR) image quality and patient dose for pediatric radiology." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001030.

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Jannetta, Adrian. "Advanced deconvolution techniques and medical radiography." Thesis, Northumbria University, 2005. http://nrl.northumbria.ac.uk/164/.

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Medical radiography is a process by which the internal structures of the human body are imaged using a source of x-rays. The images formed are essentially shadowgrams whose size and intensity is dependent on the geometry of the imaging system and the degree to which the structures attenuate x-ray radiation. The images are blurred because the x-ray source has a finite size, and noisy because the x-ray exposure must be kept as low as possible for the safety of the patient but which also limits the number of photons available for image formation. In such noisy environments traditional methods of Fourier deconvolution have limited appeal. In this research we apply maximum entropy methods (MEM) to some radiological images. We justify the choice of MEM over other deconvolution schemes by processing a selection of artificial images in which the blur and noise mimic the real situation but whose levels are known a priori. A hybrid MEM scheme is developed to address the shortcomings of so-called historic MEM in these situations. We initially consider images from situations in which the model point- spread function is assumed to be three-dimensionally spatially invariant, and which approximates the real situation reasonably well. One technique lends itself well to this investigation: magnification mammography. MEM is offered as a way of breaking some of the conflicting performance requirements of this technique and we explore several new system possibilities with a working MEM system in place. A more complicated blurring function is encountered in linear tomography, which uses opposing movements of the image receptor and x-ray source to generate planar images through an object. Features outside a particular focal plane are smeared to such an extent that detail within the focal plane can be very difficult to detect. With appropriate modification of our MEM technique, processed images show a significant reduction to the blurring outside the focal plane.

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Wojcik, Randolph Frank. "Dual energy scanning beam X -radiography." W&M ScholarWorks, 2004. https://scholarworks.wm.edu/etd/1539623461.

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Dual energy X-radiography is a method first developed in the mid-1970's by which one uses the information contained in the energy spectrum of the transmitted X-ray flux through an object. With this information one can distinguish the types of materials present in a radiograph and thus allow a computer to subtract them from the image enhancing the contrast of the remaining materials. Using this method, one can see details, which would have been hidden by overlying structures of other materials such as seen in radiographs of parts, made up of mixtures of metals and composites. There is also great interest in this technique for medical imaging of the chest where images of the organs are significantly improved by subtracting the bones. However, even with the enhanced capabilities realized with this technique, the majority of X-radiography systems only measures the bulk transmitted X-ray intensity and ignores the information contained in the energy spectrum. This is due to the added expense, time requirements, and registration problems incurred using standard radiographic methods to obtain dual energy radiographs. This dissertation describes a novel method which overcomes these problems and allows one to perform inexpensive, near real time, single shot dual energy X-radiography. The work of this thesis resulted in US patent #5,742,660.

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Xiao, Xinhua. "Automated Defect Recognition in Digital Radiography." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439309683.

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Dawson, Martin Nicholas. "Applications of neutron radiography & tomography." Thesis, University of Leeds, 2008. http://etheses.whiterose.ac.uk/1641/.

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This thesis represents the investigation and development of neutron imaging techniques as a versatile method that can be used to reveal the presence, position, size, morphology, and chemical composition of structures and materials within a sample. The underlying physics of neutron radiography and tomography mean that it has fundamental similarities to x-ray techniques, although some subtle differences mean that neutrons are often applicable in circumstances where x-rays are not. This complementarity is presented and discussed. Most of the experimental results contained herein were obtained using Neutrograph, the thermal neutron imaging instrument at the Institut Laue-Langevin's high flux research nuclear reactor in Grenoble, France. Neutrograph utilises the world's most intense neutron beam currently in use for this purpose, -3xl09 n·cm-2·s-1 across an area of 220x220 mm2, and is capable of producing high quality images with single-frame exposure times down to the millisecond regime. Meanwhile, the modest beam divergence of 6 mrad (equivalent to a beam length-to-diameter ratio, LID, of -150) can achieve a spatial resolution in the region of 150-300 11m. It is demonstrated how these properties make Neutrograph ideal for obtaining timeresolved measurements of dynamic processes in both two and three dimensions, and for imaging relatively thick samples or highly attenuating materials on a reasonable time-scale. One aspect that is addressed in this research is the potential scope of relevance of neutron imaging methods across a range of scientific disciplines. In this vein, attempts have been made not only to draw examples from a number of different fields (palaeontology, archaeology, and fluid mechanics, for example), but also to improve the performance of the instrumentation and methodology, and to establish novel techniques that will further the applicability of neutron imaging. An illustration of the latter is the use of a polarised neutron beam to investigate the presence and distribution of magnetic components in non-magnetic matrices.

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Reeves, Pauline Jane. "Models of care in diagnostic radiography." Thesis, Bangor University, 1998. https://research.bangor.ac.uk/portal/en/theses/models-of-care-in-diagnostic-radiography(e3622893-8a99-480c-a38a-6aa1b38eefeb).html.

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This research set out to develop one or more conceptual models of diagnostic radiography based on the ways in which clinical radiographers themselves viewed their skills. The report analyses the historical relationship between radiographers and radiologists and the limited attempts at theory development prior to this research. This context is set against selected literature from nursing metatheory. This comparison is made since radiography had in part developed from the nursing profession and the historical and gendered background of both professions may be seen to be similar. •The methodology is largely qualitative and the use of computers for qualitative data analysis is discussed in some detail. The data collection was completed in three major phases- a diagnostic phase; a theory development phase and an applications phase, utilising several brainstorming groups and two questionnaires as well as action research in the third phase. In the diagnostic (first) phase of the research categories representing parts of the radiographic process were derived. Two models (or theoretical frameworks) were developed and their various concepts were explored and refined. In the second phase of theory development the research was extended to develop a statement of the role of the diagnostic radiographer and several concepts from the model were explored. In the final phase, the concept of holism was explored together with the relevance of the models for the education of student radiographers. In the final sections of the report there is a detailed evaluation of the potential impact of the models including a reflexive analysis. The conclusions are that the models provide a valid conceptual representation of the radiographic process and philosophy and that they have a role to play in education of student radiographers.

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Bougeant, Olivier. "Alternative techniques of backscatter radiography Snapshot Aperture Backscatter Radiography and Collimated Segmented Detector Scatter X-ray Imaging /." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0025092.

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Chen, Kun. "A study of spectroscopic, cold neutron radiography." [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3240030.

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Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2006.
"Title from dissertation home page (viewed July 16, 2007)." Source: Dissertation Abstracts International, Volume: 67-10, Section: B, page: 5819. Adviser: Hans-Otto Meyer.

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Price, R. "Developing practice in radiography and diagnostic imaging." Thesis, University of Hertfordshire, 2007. http://hdl.handle.net/2299/1056.

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An increase in the range and capability of imaging modalities has resulted in greater demands for radiology services. This research investigates how these changes have affected role requirements and role extensions of radiographers and the consequent implications for the educational needs of radiographers. Semi-structured interviews and three successive surveys of NHS radiography managers showed that the adoption and diffusion of extended roles in radiography had increased significantly over a ten year period. Role changes included additions both to the procedures carried out by radiographers, and to the reporting of procedures, e.g. film reporting, once the domain of radiologists, is now undertaken by radiographers in many trusts. Imaging managers’ views on the factors that encouraged or deterred the introduction of extended roles were explored. While many radiographers were keen to adopt new roles, implementation was unlikely without radiological support. Respondents believed the proposed ‘four-tier structure’ would help overcome staffing difficulties, while providing an improved career framework to advance the professional status of radiographers. A key theme was the need for greater clinical knowledge to facilitate transition to advanced practice. Three studies investigated radiography education. The first used a survey to investigate the preparedness for practice of three cohorts of newly qualified radiographers. Graduates recognised the importance of continuing professional development with extended role skills identified as a priority. The second study examined the relationship between contemporary practice and UK undergraduate radiography curricula. Most programmes had responded positively to developing technology. The third study used a survey to investigate the training for extended roles provided by employers. While most provided some training, much was unaccredited, and there was considerable variation in the duration of training for similar roles. The research has documented developments taking place at a time of enormous technological innovation. It provides key data on the changing practice of radiography that will be useful to all stakeholders planning improvements to radiography services. The data lead to a re-definition of practice and recommendations for supporting education and training.

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Felipe-Valera, Elena M. "Professionalism in Radiography| A Multiple Case Study." Thesis, Keiser University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13807028.

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This study explored the perceptions that radiography faculty and students have of professionalism in health care. The purpose of this qualitative multiple case study was to understand the substance and the meaning that radiography faculty and students give to professionalism. Learning professionalism in the imaging sciences necessitates emersion in authentic experiences, which the authors call "legitimate peripheral participation," so that skills and didactic knowledge gained in a classroom can be applied in real situations among a community of experts in a field of study (Lave & Wenger, 1991). The research explored the perceptions that RT educators and students have of professionalism by asking the participants to define and describe professionalism and identify what aspects of the professional were meaningful to them. An anonymous survey and focus group discussions were used to gather the perceptions of the participants. The target population for the study was nine faculty members or instructors and ten students from the radiologic technology program of a private, not-for-profit, multi-campus university. These sets of participants were chosen because their firsthand knowledge and experiences of professionalism in the radiography program could aid in addressing the main research and sub-research questions. Both groups defined RT professionalism in terms of respect, empathy, and ethics. Important and meaningful aspects of professionalism included giving competent, compassionate patient care and assisting with diagnosis. The findings revealed that three major areas of professionalism in the imaging sciences must be addressed: interdisciplinary education, intradisciplinary education specifically around professionalism, and the development and implementation of specific competencies that encompass professionalism.

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Hudson, Lizel Sandra Ann. "Enhancing academic writing competence in radiography education." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1554.

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Thesis (MTech (Radiography))--Cape Peninsula University of Technology, 2011
This thesis records a study undertaken by a radiography lecturer at a satellite campus of a University of Technology (UoT) in the Western Cape Province of South Africa. The study investigated the academic writing practices of first year Radiation Science learners and focused on an intervention to assist learners to enhance their academic writing competence. Three research questions were addressed: 1. What did radiography learners perceive to be the factors that enabled and constrained their academic writing competence during the first year of academic study?; 2. What were the 2010 first year learners’ perceptions of the changes in their academic writing following an academic writing intervention?; and 3. According to the 2010 first year lecturers, how did the academic writing of the learners change following the intervention? To answer these questions, the research comprised two qualitative approaches: firstly a case study approach, to gain an in-depth understanding of learner writing in radiography; then the insights gained allowed for the design of an appropriate academic writing intervention, carried out in two action research spirals. Thereafter the intervention was evaluated for its impact on learners’ writing competence. The findings and interpretations from this study culminated in a forward looking model that is recommended for use by radiography educators to enhance first year learners’ academic writing competence. The model reflects a zone for the optimal enhancement of academic writing competence for entry-level learners. This ‘zone’ is created in the region of overlap of three contributing factors: collaborative guidance and support, peer mentoring and technology. The model also represents applicable underlying theories (critical theory, constructivism, and academic literacies theory) which provide the theoretical framework for enhanced academic writing competence.

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Maschio, Maria Celeste. "Performance evaluation of detector for digital radiography." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8317/.

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Lo scopo di questo lavoro è la caratterizzazione fisica del flat panel PaxScan4030CB Varian, rivelatore di raggi X impiegato in un ampio spettro di applicazioni cliniche, dalla radiografia generale alla radiologia interventistica. Nell’ambito clinico, al fine di una diagnosi accurata, è necessario avere una buona qualità dell’immagine radiologica mantenendo il più basso livello di dose rilasciata al paziente. Elemento fondamentale per ottenere questo risultato è la scelta del rivelatore di radiazione X, che deve garantire prestazioni fisiche (contrasto, risoluzione spaziale e rumore) adeguati alla specifica procedura. Le metriche oggettive che misurano queste caratteristiche sono SNR (Signal-to-Noise Ratio), MTF (Modulation Transfer Function) ed NPS (Noise Power Spectrum), che insieme contribuiscono alla misura della DQE (Detective Quantum Efficiency), il parametro più completo e adatto a stabilire le performance di un sistema di imaging. L’oggettività di queste misure consente anche di mettere a confronto tra loro diversi sistemi di rivelazione. La misura di questi parametri deve essere effettuata seguendo precisi protocolli di fisica medica, che sono stati applicati al rivelatore PaxScan4030CB presente nel laboratorio del Centro di Coordinamento di Fisica Medica, Policlinico S.Orsola. I risultati ottenuti, conformi a quelli dichiarati dal costruttore, sono stati confrontati con successo con alcuni lavori presenti in letteratura e costituiscono la base necessaria per la verifica di procedure di ottimizzazione dell’immagine radiologica attraverso interventi sul processo di emissione dei raggi X e sul trattamento informatico dell’immagine (Digital Subtraction Angiography).

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Yao, Min. "Computed radiography system modeling, simulation and optimization." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0128/document.

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Depuis plus d’un siècle, la radiographie sur film est utilisée pour le contrôle non destructif (CND) de pièces industrielles. Avec l’introduction de méthodes numériques dans le domaine médical, la communauté du CND industriel a commencé à considérer également les techniques numériques alternatives au film. La radiographie numérique (en anglais Computed radiography -CR) utilisant les écrans photostimulables (en anglais imaging plate -IP) est une voie intéressante à la fois du point de vue coût et facilité d’implémentation. Le détecteur (IP) utilisé se rapproche du film car il est flexible et réutilisable. L’exposition de l’IP aux rayons X génère une image latente qui est ensuite lue et numérisée grâce à un système de balayage optique par laser. A basse énergie, les performances du système CR sont bonnes ce qui explique son utilisation importante dans le domaine médical. A haute énergie par contre, les performances du système CR se dégradent à la fois à cause de la mauvaise absorption de l’IP mais également de la présence de rayonnement diffusé par la pièce qui, étant d’énergie plus faible, est préférentiellement absorbée par l’IP. Les normes internationales préconisent l’utilisation d’écrans métalliques pour améliorer la réponse des systèmes CR à haute énergie. Néanmoins, la nature et l’épaisseur de ces écrans n’est pas clairement définie et la gamme des configurations possibles est large. La simulation est un outil utile pour prévoir les performances d’une expérience et déterminer les meilleures conditions opératoires. Les méthodes Monte Carlo sont communément admises comme étant les plus précises pour simuler les phénomènes de transport de rayonnement, et ainsi comprendre les phénomènes physiques en jeu. Cependant, le caractère probabiliste de ces méthodes implique des temps de calcul importants, voire prohibitifs pour des géométries complexes. Les méthodes déterministes au contraire, peuvent prendre en compte des géométries complexes avec des temps de calcul raisonnables, mais l’estimation du rayonnement diffusé est plus difficile. Dans ce travail de thèse, nous avons tout d’abord mené une étude de simulation Monte Carlo afin de comprendre le fonctionnement des IP avec écrans métalliques à haute énergie pour le contrôle de pièces de forte épaisseur. Nous avons notamment suivi le trajet des photons X mais également des électrons. Quelques comparaisons expérimentales ont pu être menées à l’ESRF (European Synchrotron Radiation Facility). Puis nous avons proposé une approche de simulation hybride, qui combine l'utilisation de codes déterministe et Monte Carlo pour simuler l'imagerie d'objets de forme complexe. Cette approche prend en compte la dégradation introduite par la diffusion des rayons X et la fluorescence dans l'IP ainsi que la diffusion des photons optiques dans l'IP. Les résultats de différentes configurations de simulation ont été comparés
For over a century, film-based radiography has been used as a nondestructive testing technique for industrial inspections. With the advent of digital techniques in the medical domain, the NDT community is also considering alternative digital techniques. Computed Radiography (CR) is a cost-efficient and easy-to-implement replacement technique because it uses equipment very similar to film radiography. This technology uses flexible and reusable imaging plates (IP) as a detector to generate a latent image during x-ray exposure. With an optical scanning system, the latent image can be readout and digitized resulting in a direct digital image. CR is widely used in the medical field since it provides good performance at low energies. For industrial inspection, CR application is limited by its poor response to high energy radiation and the presence of scattering phenomena. To completely replace film radiography by such a system, its performance still needs to be improved by either finding more appropriate IPs or by optimizing operating conditions. Guidelines have been addressed in international standards to ensure a good image quality supplied by CR system, where metallic screens are recommended for the case of using high energy sources. However, the type and thickness of such a screen are not clearly defined and a large panel of possible configurations does exist. Simulation is a very useful tool to predict experimental outcomes and determine the optimal operating conditions. The Monte Carlo (MC) methods are widely accepted as the most accurate method to simulate radiation transport problems. It can give insight about physical phenomena, but due to its random nature, a large amount of computational time is required, especially for simulations involving complex geometries. Deterministic methods, on the other hand, can handle easily complex geometry, and are quite efficient. However, the estimation of scattering effects is more difficult with deterministic methods. In this thesis work, we have started with a Monte Carlo simulation study in order to investigate the physical phenomena involved in IP and in metallic screens at high energies. In particular we have studied separately the behavior of X-ray photons and electrons. Some experimental comparisons have been carried out at the European Synchrotron Radiation Facility. Then, we have proposed a hybrid simulation approach, combining the use of deterministic and Monte Carlo code, for simulating the imaging of complex shapes objects. This approach takes into account degradation introduced by X-ray scattering and fluorescence inside IP, as well as optical photons scattering during readout process. Different simulation configurations have been compared

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Rivetti, Di Val Cervo Stefano <1975&gt. "Performance evaluation of detectors for digital radiography." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3611/1/stefano_rivetti_tesi.pdf.

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To date the hospital radiological workflow is completing a transition from analog to digital technology. Since the X-rays digital detection technologies have become mature, hospitals are trading on the natural devices turnover to replace the conventional screen film devices with digital ones. The transition process is complex and involves not just the equipment replacement but also new arrangements for image transmission, display (and reporting) and storage. This work is focused on 2D digital detector’s characterization with a concern to specific clinical application; the systems features linked to the image quality are analyzed to assess the clinical performances, the conversion efficiency, and the minimum dose necessary to get an acceptable image. The first section overviews the digital detector technologies focusing on the recent and promising technological developments. The second section contains a description of the characterization methods considered in this thesis categorized in physical, psychophysical and clinical; theory, models and procedures are described as well. The third section contains a set of characterizations performed on new equipments that appears to be some of the most advanced technologies available to date. The fourth section deals with some procedures and schemes employed for quality assurance programs.

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Rivetti, Di Val Cervo Stefano <1975&gt. "Performance evaluation of detectors for digital radiography." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3611/.

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To date the hospital radiological workflow is completing a transition from analog to digital technology. Since the X-rays digital detection technologies have become mature, hospitals are trading on the natural devices turnover to replace the conventional screen film devices with digital ones. The transition process is complex and involves not just the equipment replacement but also new arrangements for image transmission, display (and reporting) and storage. This work is focused on 2D digital detector’s characterization with a concern to specific clinical application; the systems features linked to the image quality are analyzed to assess the clinical performances, the conversion efficiency, and the minimum dose necessary to get an acceptable image. The first section overviews the digital detector technologies focusing on the recent and promising technological developments. The second section contains a description of the characterization methods considered in this thesis categorized in physical, psychophysical and clinical; theory, models and procedures are described as well. The third section contains a set of characterizations performed on new equipments that appears to be some of the most advanced technologies available to date. The fourth section deals with some procedures and schemes employed for quality assurance programs.

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Klein, Caroline Gugisch. "Avaliação da arquitetura óssea trabecular por meio de processamento de imagem digital em radiografias panorâmicas." Centro Federal de Educação Tecnológica do Paraná, 2005. http://repositorio.utfpr.edu.br/jspui/handle/1/102.

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Este trabalho teve como objetivo modificar um algoritmo de esqueletização e criar outro para quantificar imagens radiográficas. Foi proposto um tratamento digital em radiografias panorâmicas de 50 voluntárias diagnosticadas como osteoporóticas e não osteoporóticas em um estudo anterior. Para verificar a validade deste recurso digital, foi elaborado um questionário que juntamente com as radiografias foi distribuído entre quinze examinadores radiologistas. Estes analisaram de forma subjetiva 99 imagens, respondendo quais os critérios adotados para a avaliação da arquitetura óssea trabecular. Os dados obtidos no questionário aplicado e no tratamento digital das imagens foram submetidos à análise descritiva para verificar o nível de concordância nas hipóteses de diagnóstico e definir um padrão ouro. Foi construída uma curva ROC, para verificar o ponto de corte e estabelecer qual filtro de Gauss era o melhor, com raio variável de 30, 35, 40, 45 ou 50. O filtro escolhido foi o de raio 30, pois apresentou melhor especificidade (94,3%), mesmo tendo uma baixa sensibilidade (50%). Os níveis de concordância entre os examinadores ficaram abaixo de 80%. Contudo foi registrada alta significância entre os dados percentuais de pontos pretos e de pontos terminais (p<0.001). O processamento de imagens através da esqueletização em radiografias panorâmicas pode tornar-se um valioso recurso para os cirurgiões-dentistas.
The purpose of the present work was to modify a skeletonization algorithm and to create an algorithm to quantify radiographic images. A panoramic radiographic digital treatment of 50 volunteers diagnosed as otheoporotics and non-ostheoporotics in a previous work was done. In order to verify the validity of the digital resource, a questionnaire was elaborated that along with the radiographies was distributed among 15 radiologists. The examiners analyzed in a subjective way 99 images, responding which criteria were adopted for the evaluation of the trabecular bone architecture. The data obtained in the applied questionnaire and in the digital image treatment were submitted to a descriptive analysis in order to verify the agreement in the diagnostic hypothesis and to define a golden standard. A ROC curve was built to check the cut point and to establish which Gauss filter was the best, with a variable ratio of 30, 35, 40, 45, or 50. The ratio 30 filter was chosen since it presented the best specificity (94.3%), even having a low sensibility (50%). The agreement levels among the examiners were below 80%. However a high significance among the percentage of black points was registered (p<0.001). The method of image processing trough the skeletonization in panoramic radiographies can become a valuable support for the dentist-surgeons.

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Yeo, Daxter Kai Loon. "Distortions in panoramic radiographs /." [St. Lucia, Qld. : s.n.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16647.pdf.

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Abdelrahman, Magdy Shehata. "Scattering correction and image restoration in neutron radiography and computed tomography." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3025066.

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Yakoubian, Jeffrey Scott. "Adaptive histogram equalization for mammographic image processing." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/16387.

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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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Forman, D. "Shared learning : monitoring the attitudinal changes of staff and students on undergraduate health care professional programmes." Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/19656/.

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The aim of this investigation was to monitor attitudinal changes of staff and students participating in undergraduate professional programmes to the implementation of shared learning over a four-year period. The programmes being studied were the BSc. Occupational Therapy, BSc. Diagnostic Radiography and BSc. Therapeutic Radiography Honours degrees. Each validated programme contained some syllabus areas that were taught together i.e. were shared across the professions. Initially, after a review of the existing literature on this issue, a questionnaire was designed as a research tool to enable both qualitative and quantitative data to be collected and analysed. The quantitative sections of the questionnaire were checked for reliability throughout the four years and achieved positive Cronbach Alpha results ranging from .7083 to .8984 in the four main concepts under investigation, namely the Pitfalls, Benefits, Curriculum Aspects and Social Aspects of the shared programmes. Over the four year period a total of 418 student questionnaires were collected and analysed. In addition to the quantitative data collected, qualitative data were also collected from the questionnaire from extracts of the minutes of Course Committee and Examination Board meetings and from videos of tutorials and seminars. All of these were analysed. The results showed fluctuations in the attitudes of both staff and students to shared learning over the four year period, but all those who participated showed a net favourable change in attitude by the end of the research investigation.

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Stamatakis, Harry Charalabos. "Physical and psychophysical properties of digital intraoral radiography /." Stockholm, 1999. http://diss.kib.ki.se/1999/91-628-3799-0/.

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Fink, David Walter. "Detecting corrosion in aircraft components using neutron radiography." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/39993.

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Borges, Nicholas P. "Improving Imaging Techniques and Resolution in Neutron Radiography." Digital WPI, 2020. https://digitalcommons.wpi.edu/etd-dissertations/604.

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Hydrogenous samples, such as biological tissues, analyzed in a neutron radiography geometry display reduced image contrast and resolution due to excessive image contributions from scattered neutrons produced from the high neutron-scatter cross section with hydrogen. Because of this, neutrons presently are not used for thick-tissue(>2.5cm) or in-vivo imaging. Two methods of neutron scatter rejection and event centroiding, were employed to enhance the quality of biological neutron imaging by reducing image blurring noise caused by hydrogen and increasing the contrast ratio of the detector. By employing the techniques used herein, event centroiding can increase the natural resolution of the detector by a factor of two without energy dependence and as much as 4 times with energy bins. Scatter rejection can increase the contrast resolution by 7%-10% of an imaging standard and can resolve a 160 μm image through 6mm of acrylic.

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ALBERTIN, Fauzia. "K-edge Radiography and applications to Cultural Heritage." Doctoral thesis, Università degli studi di Ferrara, 2011. http://hdl.handle.net/11392/2388734.

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The present work of thesis is focused on application of X-ray K-edge technique to paintings. This technique allows one to achieve a topographic map of a pigment on the whole surface of the painting. The digital acquisition of radiographic images by using monochromatic X-ray beams allows to take advantage of the sharp rise of X-ray absorption coefficient of the elements, the K-edge discontinuity. Working at different energies, bracketing the K-edge peak, allows recognition of the target element. The K-edge radiography facility installed at Larix Laboratory, at Department of Physics in Ferrara, consists of a quasi-monochromatic X-ray beam obtained via Bragg diffraction on a mosaic crystal from standard X-ray source. In this work the K-edge technique and the facility used are illustrated. A characterization of the monochromatic beams in the energy range 7-40 KeV range and the elemental mapping on pictorial layers obtained are presented. At the end, a transportable facility for digital radiography is presented and some radiographic analysis of works of art performed are shown.

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Lucchese, M. "TOTAL VARIATION POISSON NOISE REMOVAL IN DIGITAL RADIOGRAPHY." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/203243.

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Since the digital X-Ray images are the results of a measurement process, they are affected by noise. Linear filters remove the fluctuations of pixels value related to the presence of noise attenuating or removing the high frequency content of the images, having the drawback that they smooth also the edges and so they corrupt structural information inside them. A more principled approach, widely adopted for image denoising since the paper of Rudin et al., is based on regularization. In this framework the filtered image is obtained through the maximization of a properly defined cost function, in which both the distance between the filtered and the measured image and user-defined a-priori characteristics of the image data are considered. Many authors demonstrated that a Total Variation (TV) a-priori term leads to an effective, edge preserving denoising algorithm generally termed TV-regularization. From a Bayesian point of view, the filtered image maximizes the posterior probability composed by the likelihood term, that expresses the distance between filtered and measured image, and the prior probability, which describes the desired characteristics of the solution in statistical form. The TV filter, in the considered case, depends on the regularization parameter and on a parameter introduced in order provides differentiability of the regularization term. The effect of the latter parameter produces a loss of sensibility of the regularization term to the image gradients with "small" magnitude, so it is suggested to set it to a small value. Optimality of the regularization parameter has been expressed in terms of similarity between the filtered and the noise-free images. Through the similarity indexes presented in this work it has seen that the optimal value of the regularization parameter is somehow related to the images' features. Low frequency and low photons count images (images with lower SNR) require a higher regularization effect, so the optimal value of the regularization parameter assumes higher values. However, for the case of real images, we do not have the noise-free image and the value of the regularization parameter has to be derived from the measured image and the filtered one. Several attempts in this direction have been proposed, especially for the Gaussian noise and Tikhonov regularizer case . These are based on the "Discrepancy principle" that states that the residual should have the same distribution of the noise on the image. We have adapted this principle to the Poisson noise case with TV regularizer, considering the fact that, in the Poisson noise, there is a dependency between the signal level and the noise variance and defined a criterion to automatically set the most adequate value of the regularization parameter. The filtering performance have been translates as the similarity between the filtered and noise-free images. The similarity between images is evaluated in term of the distance between images by using the classical indexes derived from signal processing, like sum of squares or Peak Signal to Noise ratio, but also with the newly introduced indices based on the Human Visual System properties, like Structure Similarity (SSIM) and Feature Similarity (FSIM). In the case of high photons count images NMAE (Normalized MAE), PSNR, RMSE, and FSIM generally agree in identifying the optimal value of the regularization parameter for radiographs with high SNR, while for low photon counts (low SNR), FSIM prefers more smoothed images with respect to NMAE, RMSE and PSNR; in this context, it is not clear which of the indexes provides the best image quality evaluation. Finally the SSIM index always select as optimal over-smoothed images and it does not appear to be a reliable quality index. We noticed that during the filtering process of images with low spatial frequency content the similarity between the filtered image and the noise-free one increases in the first iterations, reaches a maximum value, and then it starts to decrease while the cost function monotonically decreases throughout. We have further analysed this and we show that in high photon count regions the optimization algorithms, in the later iterations, cuts the image valleys and ridges introducing spurious plateaus. As a result, the image is locally over-smoothed. This is explained by considering the fact that since the likelihood term comes from the Poisson distribution, allows a large correction in the high photon count area and only small corrections in the low-photon count areas. This imply that the weight of the likelihood term, in the whole cost function is signal dependent, and in the high photon count area the regularization term is predominant. Lastly we have compared TV regularization with another family of denoising algorithms based on wavelet decomposition, widely used in image processing in general: the Bayesian Least Squares - Gaussian Scale Mixture(BLS-GSM), that has been proposed by Portilla et al., for the denoising of images corrupted by Gaussian noise. This algorithm has been extended also to the Poisson case, by using an improved version of the Anscombe inverse transformation. Results on real and simulated images have shown the superiority of the BLS-GSM with respect to the Total Variation on the low frequency images and on the real ones. As higher frequencies are incorporated, the two methods show similar behavior and TV regularization performs better for very high frequency images, whose frequency content is more similar to the assumptions of total variation.

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Ley, Paul J. "An in-vitro comparison of working length determination between a digital system and conventional film when source-film/sensor distance and exposure time are modified." Connect to resource online, 2009. http://hdl.handle.net/1805/1928.

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Thesis (M.S.D.)--Indiana University School of Dentistry, 2009.
Title from PDF t.p. (viewed Aug. 11, 2009) Advisors: Mychel Vail, Chair of the Research Committee, Susan Zunt, Ted Parks, Kenneth Sponik, Joseph Legan. Curriculum vitae. Includes abstract. Includes bibliographical references (leaves 103-119).

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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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43

Brooks, Kenneth W. "Automated analysis of mammography phantom images." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17900.

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44

Peng, Jinghong P. "Automated acceptance criteria for the American College of Radiology (ACR) mammographic accreditation phantom images." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/18248.

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45

湯添發 and Thiam-huat Tng. "Validity of cephalometric landmarks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B38628399.

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Snaith, Beverly. "Development of the radiography evidence base: An examination of advancing practice." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/6314.

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Radiography has seen most development over the last 30 years with the evolution of new technologies, but perhaps more significantly changes in education models and radiographer roles. The development of advanced and consultant posts has facilitated the growth of the profession, although the evidence base is still evolving. Through a number of research projects this thesis will explore the growth in the radiography evidence base with specific reference to the extending role of the radiographer in image interpretation. Parallel clinical and academic developments have provided evidence of a scholarly profession which is slowly establishing its place through publication and a growing research base.
Please Note: The full text of each of the published articles, which are listed on page vii, has been removed from the PhD online copy due to publisher copyright restrictions. Links to the publisher¿s websites are given. To see the final full text version of the articles listed on page vii, please visit the publisher¿s website. Available access to the published online version may require a subscription.

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Odau, James R. "Determining applicant aptitude as a predictor of success in a radiography program." Online version, 1999. http://www.uwstout.edu/lib/thesis/1999/1999odauj.pdf.

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Woodward, Stephanie. "Development and applications of a pulsed neutron radiography system." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46916.

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Gobbi, David G. "A high-pressure gas microstrip detector for digital radiography." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ27049.pdf.

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Hunter, David MacKenzie. "Digital radiography by laser-scanned readout of amorphous selenium." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ45465.pdf.

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Dissertations / Theses on the topic 'Radiography'

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