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This extended essay presents seven scholarly papers (1994- 2008) from my fifty six papers including five book chapters, revealing their collective significant importance to and impact on establishing and advancing the practice, education and profession of Radiography internationally. Method: This essay is underpinned by the premise that research improves teaching and it shows by critical and thematic analysis how the papers achieve their purpose of establishing and advancing the practice, education and profession of radiography internationally. A critical discussion of the work is undertaken by investigating factors that measure its impact. Results: Comprehensive, objective information is provided cataloguing the originality, utility, diversity, citation rate and longevity of the work, which fall into three areas: pedagogical research within Medical Imaging - Papers 2, 3, 6 and 7 , contrast agents - Papers 5 and maintaining uptakes rates for breast screening - Paper 1. These papers prove my credibility as a researcher and thus an "authority" to write the "how to" papers aimed at up skilling the profession e.g. via Paper 4. Paper 1 was cited forty six times over sixteen years in thirty five different peer reviewed international journals with a wide range of foci. These journals demonstrate impact factors as high as 7.514 for Cancer Epidemiology, Biomarkets and Prevention and 5.996 for Radiology, the highest impact factor Radiology journal. This paper was a seminal work. Paper 4 has been down loaded in excess of 6000 times and five years on (2010) remains first in the top 25 "hottest" downloaded papers in Radiography. My work as Project Co-ordinator for the Higher Education Network of Radiographers in Europe (HEN RE) clearly built on the work of earlier staff. My subsequent work as Project Co- ordinator has impacted on fifty universities in the European Union (EU) / European Economic - Paper 7, as well as eighteen countries via citations, conferences, teaching exchanges, consultancy and participation in four E.U. projects. Overall my submitted papers have been cited in the peer reviewed international journals of twenty three medical and related professions, in a total of forty five peer reviewed journals. There were 59 citations in total. For the six papers for which downloads are available, on submission April 2010, there had been 11,414 downloads. Conclusion: This supporting paper, supported by objective data regarding impact, demonstrates how the papers presented meet the purpose of this work. This distinctive, original work demonstrates a depth of scholarship commensurate with the requirements of the award.

RATIONALE AND OBJECTIVES: Radiological error due to the incorrect interpretation of medical images still occurs in current practice, and continues to be reported both in laboratory and clinical experimental conditions. In general radiological practice error rates range from 3 - 5%. However, that scale reaches up to 30% for detection of some early pulmonary cancers. Computer-Aided Detection (CAD) algorithms have been proposed to support human observers in verifying their choices. Although CAD systems might help in certain situations, its general implementation in clinical practice is still controversial. Perceptual studies involving psychophysical approaches to the error problem may give some insight into the gap between advances in image processing and the nature of radiological expertise. Moreover, some neuroscientific evidence underlines the importance of processing spatial frequency properties of visual stimuli that is carried out by the Human Visual System (HVS). This has provided the inspiration for Spatial Frequency Analysis of certain Regions of Interest (ROI) selected by human observers in medical image interpretation in a number of studies. Such studies have been conducted in mammography focusing on the relationship between the physical properties, the type of radiological outcomes and the dwelling time. The spatial frequency features in mammograms have very specific features however, and this leads to the question of whether the results for mammography could be generalised to other medical images. RESEARCH AIMS: This study aims to investigate the perceptual criteria used in decision-making processes in pulmonary lung nodule detection from Posterior-Anterior (PA) Chest Radiographs (CxR). Moreover, the development in radiological expertise has been taken into account by comparing the results obtained from subjects with different levels of experience in the field. MATERIALS AND METHODOLOGY: Ten participant observers were selected from each of the following groups:  radiologists and reporting radiographers (experts),  radiography students (two levels of novices) and those  without any relevant experience (naive). 11 ~ •• ------------~=== Subjects participated in the eye tracking experiment during lung nodule detection from a set of PA radiographs with a 50% prevalence of pathology. Twenty radiological cases were included in the data bank., where ten contained one to five nodules. The assessment of performance for each individual was calculated based on Jack-knife Alternative Free-response Receiver Operating Characteristic Figure of Merit (JAFROC FOM). Eye tracking data was used to divide images into areas of foveal visual attention distribution from the most dwelled to totally ignored Regions of Interest (ROI). These selected sites were analysed in terms of spatial frequency properties using 2D Stationary Wavelet Packets Transform (SWPT) frames by Dubieties functions up to three levels of decomposition. The logarithm of energy carried by each wavelet coefficient represents the amount of visual information coded by the spatial frequency range ω1 = f(ωx/ωy) in a particular orientation θi = g(tag(ωx/ωy)) and is called Spatial Frequency Band (SFBj). A reduction procedure was applied to eliminate redundancy in information coding by a set of SFB. Thus, 84 bands obtained from the third level of decomposition were reduced to twenty nine bands. The degree of dissimilarity in spatial frequency domains between selected regions was explored by statistical analysis on wavelet representations at the sites of subjects' responses. The locality of selected sites was limited by the foveal Field of View (FOV). The dissimilarities between wavelet representations were measured according to the number of non-redundant SFBj within which significant differences (p<0.05) were found according to an analysis of variance (ANOV A) with post hoc test. The statistical analysis embraced subject-related factors (expertise level, JAFROC FOM, dwell time) and image-based features (nodule detectability, conspicuity, localization and spatial frequency description). These factors were considered as independent variables in visual attention distribution and decision-sites studies. RESULTS: The correctness of the second or higher order responses were highly correlated with the category of first decision-outcomes made on the case. That correlation shows the probability of accurate end-point decisions related to the first decision. Experts are more accurate in dedicating visual attention to the more relevant areas containing pulmonary nodules. Significant differences were found in the spatial frequency domain between nodule-containing regions which have been fixated and those which were left without focal attention. The JAFROC FOM calculation based on overall performance characterizes the more experienced subjects as being more accurate in decision-making and less variable in FOM value within a group. Moreover, the high accuracy of subject performance was correlated with the allocation of visual attention in normal regions which are more similar to the nodule-containing sites,.in terms of the spatial frequency features. The experts' ability in distinguishing the most attractive True- Negative (TN) from True-Positive (TP) avoiding False-Positive (FP) was proven with differences at the spatial frequency level. High correlation between the correctness of a first overt decision made on certain cases and the .quality performance was found significant (r=D. 75), The category of the first response effects the perceptual criteria applied to form the final decision outcome. CONCLUSIONS: The main contribution to knowledge of this work is that for the first time the SF A was conducted on a radiological task other than mammography. The work lends significant weight to the argument that spatial frequency channels coded through a wavelet paradigm are a characterising feature of visual perception and that this is phenomenon is generalisable to areas of radiology other than breast imaging, where mammographs are quite unique in terms of image-based features compare to pictures obtained from other medical irnaging modalities. Also, this work contributes an extension to previous studies on non-expert groups through investigation into trends in development of radiological experience. There is some agreement with the conclusions presented by others who suggest that experts may use specific neural connections - a set of spatial frequency channels tuned to specific object detection - during visual searching in a radiological task.

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This project looks at the design of an in-line X-ray phase contrast imaging system, based around the Bede Microsource®, on a suitable scale for imaging small pathological samples. The system is applied to two test objects to assess feasibility of its use in practice. The system comprises: microfocus X-ray source, copper and rhodium targets, phase object and detector. By altering sample position, phase contrast is seen to vary proportionally with propagation distance. By increasing source size, phase contrast is seen to degrade with increasing source dimensions. It is furthermore determined that transverse coherence in the direction perpendicular to a sample boundary dominates the result. Using different operating voltages with an image manipulation approach, the importance of monochromaticity is investigated. It is determined that less polychromatic X-rays provide better phase contrast. However, applying a filter method of monochromation reduces phase contrast due to beam hardening, so this method is unsuitable for phase imaging with this system. By increasing sample thickness, phase contrast is seen to plateau at a certain thickness, dependant on X-ray energy, revealing a practical limitation of the system. Introduction of water and glass to the system is seen to be detrimental to phase contrast, due to beam hardening. However phase contrast is not destroyed by the presence of water. When imaging a mammographic test object comprising low-contrast details and breast tissue morphology, the system detects all low-contrast details extremely well. Furthermore, using a phase object together with breast tissue morphology, with the harder rhodium X-rays, the system detects an anomaly of -500J.!m through the noise of simulated breast tissue. Finally, we see the difference in two scorpion sting images: an absorption image taken at the beginning of the project and a phase image taken after the system has been improved.

The aim of this project is to examine how specialisation in diagnostic radiography has occurred. In particular, this research aims to examine the contemporary ethos of specialism in diagnostic radiography; how the higher status of technology has developed over patient-centredness; the impact of the working relationship between radiology and diagnostic radiography on this development; the relationship between gender and the nature of occupation in the development of diagnostic radiography. Qualitative data was collected using 31 semi-structured interviews that took the form of oral histories where possible. The time-span covered is 1932-2001. Findings show that a paradigm shift is required. Defining specialism and expert practice is difficult, as both are negotiated constructs that tend to have local meaning. Not all specialisms in diagnostic radiography increase professional autonomy and management has a key role to play in the development of radiography as a profession to enable full engagement with consultant status. To a great extent, diagnostic radiography and its associated specialisms is governed by an emphasis on technology rather than the patient. This emphasis has roots in power difference between radiologists and radiographers and within the hierarchy of radiography. Radiologists have controlled radiographers to provide a service to radiology rather than the patients, and, although this is still evident in some hospitals, it is changing. Task offloading from radiologists to radiographers confuses the notions of specialism and radiography is in danger of seeking professional development through emulating radiology rather than using radiographic caring skills and expanding practice with a humanistic and patient focused emphasis. Radiography emerged as a pioneering, elite profession that could originally be regarded as a specialism of nursing. Technology and medicine gradually reduced radiographic practice to have a technological and quantitative focus. There is now a demand to once again broaden radiographic practice to actively contribute to a patient-centred service in an autonomous, more qualitative and self-directed manner. A collection of oral histories has been a direct result of this research. Specialisms are a broad area of diagnostic radiography and rather than focus on technological areas of practice, a more holistic range of specialisms could be embraced to enable the profession to progress.

Digital imaging has long been available in radiology in the form of computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound. Initially the transition to general radiography was slow and fragmented but in the last 10-15 years in particular, huge investment by the manufacturers, greater and cheaper computing power, inexpensive digital storage and high bandwidth data transfer networks have lead to an enormous increase in the number of digital radiography systems in the UK. There are a number of competing digital radiography (DR) technologies, the most common are computer radiography (CR) systems followed by indirect digital radiography (IDR) systems. To ensure and maintain diagnostic quality and effectiveness in the radiology department appropriate methods are required to evaluate and optimise the performance of DR systems. Current semi-quantitative test object based methods routinely used to examine DR performance suffer known short comings, mainly due to the subjective nature of the test results and difficulty in maintaining a constant decision threshold among observers with time. Objective image quality based measurements of noise power spectra (NPS) and modulation transfer function (MTF) are the ‘gold standard’ for assessing image quality. Advantages these metrics afford are due to their objective nature, the comprehensive noise analysis they permit and in the fact that they have been reported to be relatively more sensitive to changes in detector performance. The advent of DR systems and access to digital image data has opened up new opportunities in applying such measurements to routine quality control and this project initially focuses on obtaining NPS and MTF results for 12 IDR systems in routine clinical use. Appropriate automatic exposure control (AEC) device calibration and a reproducible measurement method are key to optimising X-ray equipment for digital radiography. The uses of various parameters to calibrate AEC devices specifically for DR were explored in the next part of the project and calibration methods recommended. Practical advice on dosemeter selection, measurement technique and phantoms were also given. A model was developed as part of the project to simulate CNR to optimise beam quality for chest radiography with an IDR system. The values were simulated for a chest phantom and adjusted to describe the performance of the system by inputting data on phosphor sensitivity, the signal transfer function (STF), the scatter removal method and the automatic exposure control (AEC) responses. The simulated values showed good agreement with empirical data measured from images of the phantom and so provide validation of the calculation methodology. It was then possible to apply the calculation technique to imaging of tissues to investigate optimisation of exposure parameters. The behaviour of a range of imaging phosphors in terms of energy response and variation in CNR with tube potential and various filtration options were investigated. Optimum exposure factors were presented in terms of kV-mAs regulation curves and the large dose savings achieved using additional metal filters were emphasised. Optimum tube potentials for imaging a simulated lesion in patient equivalent thicknesses of water ranging from 5-40 cm thick for example were: 90-110kVp for CsI (IDR); 80-100kVp for Gd2O2S (screen /film); and 65-85kVp for BaFBrI. Plots of CNR values allowed useful conclusions regarding the expected clinical operation of the various DR phosphors. For example 80-90 kVp was appropriate for maintaining image quality over an entire chest radiograph in CR whereas higher tube potentials of 100-110 kVp were indicated for the CsI IDR system. Better image quality is achievable for pelvic radiographs at lower tube potentials for the majority of detectors however, for gadolinium oxysulphide 70-80 kVp gives the best image quality. The relative phosphor sensitivity and energy response with tube potential were also calculated for a range of DR phosphors. Caesium iodide image receptors were significantly more sensitive than the other systems. The percentage relative sensitivities of the image receptors averaged over the diagnostic kV range were used to provide a method of indicating what the likely clinically operational dose levels would be, for example results suggested 1.8 µGy for CsI (IDR); 2.8 µGy for Gd2O2S (Screen/film); and 3.8 µGy for BaFBrI (CR). The efficiency of scatter reduction methods for DR using a range of grids and air gaps were also reviewed. The performance of various scatter reduction methods: 17/70; 15/80; 8/40 Pb grids and 15 cm and 20 cm air gaps were evaluated in terms of the improvement in CNR they afford, using two different models. The first, simpler model assumed quantum noise only and a photon counting detector. The second model incorporated quantum noise and system noise for a specific CsI detector and assumed the detector was energy integrating. Both models allowed the same general conclusions and suggest improved performance for air gaps over grids for medium to low scatter factors and both models suggest the best choice of grid for digital systems is the 15/80 grid, achieving comparable or better performance than air gaps for high scatter factors. The development, analysis and discussion of AEC calibration, CNR value, phosphor energy response, and scatter reduction methods are then brought together to form a practical step by step recipe that may be followed to optimise digital technology for clinical use. Finally, CNR results suggest the addition of 0.2 mm of copper filtration will have a negligible effect on image quality in DR. A comprehensive study examining the effect of copper filtration on image quality was performed using receiver operator characteristic (ROC) methodology to include observer performance in the analysis. A total of 3,600 observations from 80 radiographs and 3 observers were analysed to provide a confidence interval of 95% in detecting differences in image quality. There was no statistical difference found when 0.2 mm copper filtration was used and the benefit of the dose saving promote it as a valuable optimisation tool.

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.

Ioversol and Iomeprol are radiological contrast media commonly used interchangeably in many South African imaging facilities for coronary angiography. Despite differences in chemical composition, they are presumed to have similar renal safety profiles. However, no studies directly compare the renal safety of these two contrast media for coronary angiography in a predominantly healthy population. A systematic review was performed to establish which contrast medium is safer. Articles were sourced from Medline, CINAHL, Scopus, Science Direct, and PubMed Clinical Queries databases. Eligible studies were peer-reviewed articles of coronary angiography examinations carried out on a healthy adult population, where Ioversol or Iomeprol or both were administered, with contrast-induced nephropathy as an end-point. Six articles with a total population of 2431 patients were selected. The Cochrane Risk of Bias Tool was used in evaluating included articles. Pooling studies using the random effects model did not show a statistically significant reduction in contrast-induced nephropathy when Iomeprol was administered (Risk ratio 1.14, 95% confidence interval 0.797-1.643, p = 0.466). Moderate heterogeneity (I2=54.21%) across the studies was observed. Study limitations included potential bias during data extraction because this was performed by a single reviewer, and language restrictions to include only English titles. Iomeprol may be better for use in the clinical setting because of more a predictable renal safety profile. / Health Studies / M. P. H. (Health Studies)