296 research outputs found

    Using Raman Spectroscopy for Intraoperative Margin Analysis in Breast Conserving Surgery

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    Breast Conserving Surgery (BCS) in the treatment of breast cancer aims to provide optimal oncological results, with minimal tissue excision to optimise cosmetic outcome. Positive margins due to an inadequate resection occurs in 17% of UK patients undergoing BCS and prompts recommendation for further tissue re-excision to reduce recurrence risk. A second operation causes patient anxiety and significant healthcare costs. This issue could be resolved with accurate intra-operative margin analysis (IMA) to enable excision of all cancerous tissue at the index procedure. High wavenumber Raman Spectroscopy (HWN RS) is a vibrational spectroscopy highly sensitive to changes in protein/lipid environment and water content –biochemical differences found between tumour and normal breast tissue. We proposed that HWN RS could be used to differentiate between tumour and non-tumour breast tissue with a view to future IMA. This thesis presents the development of a Raman system to measure the HWN region capable of accurately detecting changes in protein, lipid and water content, in the presence of highly fluorescent surgical pigments such as blue dye that are present in surgically excised specimens. We investigate the relationship between changes in the HWN spectra with changes in water content in constructed breast phantoms to mimic protein and lipid rich environments and biological tissue. Human breast tissue of paired tumour and non-tumour samples were then measured and analysed. We found that breast tumour tissue is a protein rich, high water, low fat environment and that non-tumour is a low protein, fat rich environment with a low water content, and this can be used to identify breast cancer using HWN RS with excellent accuracy of over 90%. This thesis demonstrates a HWN RS Raman system capable of differentiating between tumour and non-tumour tissue in human breast tissue, and this has the potential to provide IMA in BCS

    A Poststructural Autoethnography: Self as event

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    This thesis takes the form of a poststructural autoethnography. It explores self as event in order to illustrate the fluid nature of self identities, and is informed by the writings of Michel Foucault, Jacques Derrida, Gilles Deleuze and Felix Guattari. In tandem with these theorists, I turn to the work of Michael White, narrative therapist, in my use of his Migration of Identity map (White, 1995) and the eight-point conversational map he developed to address personal failure (White, 2002). The launching points for my research were selected stories that significantly shaped my life, specifically two storylines of how I became mired in problem stories of blame and failure that lead to exhaustion and burnout. Taking a poststructural narrative therapeutic perspective has opened up space to bring forward subordinate, alternative stories that were previously overpowered by problem stories. In the process of troubling the discourses, and sedimented practices of those events and their subsequent effects, I have had opportunity to open up the possibility of transformation – taking off in lines of flight. Through plugging in to Deleuzo-Guattarian concepts, I also explore a professional relationship I had with my plastic surgeon across the decomposition and re-composition of facial identity. Drawing on the work of Deleuze and Guattari (1987) made transformation possible, a freeing up of the constraining lines of force, movement that takes the research subject (my self) into different territory of being. The research became an opportunity to explore a migration of identity and to act to open the possibility for conceiving of self as fluid, a work in progress, self as a work of art. Writing plays an important part in this research and in bringing the self into existence. To this end, the thesis charts the course of a journey of compassionately witnessing self, and in the process, both reveals and troubles the positions offered and refused by the subject. Finally, this autoethnography is a journey towards ethical reflexive practice as it connects me to my desire to do the right thing – to become an ethical counselling practitioner, and to highlight the movement of becoming. I understand this reflexivity to be a continual process that makes possible a questioning of practice that explores effects of the work I do, how it contributes to others’ lives, and how others contribute to my life. I explore the process of becoming different through this witnessing of self, and, in the process, discover how this makes a compassionate witnessing of other possible. Witnessing of other brings me closer to doing hope in community, while, at the same time, scales it down to make it do-able, reasonable hope. This heightened awareness makes possible the witnessing of sparkling moments in therapeutic conversations and makes visible the possible in the impossible, and the impossible in the possible

    Registration of ultrasound and computed tomography for guidance of laparoscopic liver surgery

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    Laparoscopic Ultrasound (LUS) imaging is a standard tool used for image-guidance during laparoscopic liver resection, as it provides real-time information on the internal structure of the liver. However, LUS probes are di cult to handle and their resulting images hard to interpret. Additionally, some anatomical targets such as tumours are not always visible, making the LUS guidance less e ective. To solve this problem, registration between the LUS images and a pre-operative Computed Tomography (CT) scan using information from blood vessels has been previously proposed. By merging these two modalities, the relative position between the LUS images and the anatomy of CT is obtained and both can be used to guide the surgeon. The problem of LUS to CT registration is specially challenging, as besides being a multi-modal registration, the eld of view of LUS is signi cantly smaller than that of CT. Therefore, this problem becomes poorly constrained and typically an accurate initialisation is needed. Also, the liver is highly deformed during laparoscopy, complicating the problem further. So far, the methods presented in the literature are not clinically feasible as they depend on manually set correspondences between both images. In this thesis, a solution for this registration problem that may be more transferable to the clinic is proposed. Firstly, traditional registration approaches comprised of manual initialisation and optimisation of a cost function are studied. Secondly, it is demonstrated that a globally optimal registration without a manual initialisation is possible. Finally, a new globally optimal solution that does not require commonly used tracking technologies is proposed and validated. The resulting approach provides clinical value as it does not require manual interaction in the operating room or tracking devices. Furthermore, the proposed method could potentially be applied to other image-guidance problems that require registration between ultrasound and a pre-operative scan

    Mapping and Merging Using Sound and Vision : Automatic Calibration and Map Fusion with Statistical Deformations

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    Over the last couple of years both cameras, audio and radio sensors have become cheaper and more common in our everyday lives. Such sensors can be used to create maps of where the sensors are positioned and the appearance of the surroundings. For sound and radio, the process of estimating the sender and receiver positions from time of arrival (TOA) or time-difference of arrival (TDOA) measurements is referred to as automatic calibration. The corresponding process for images is to estimate the camera positions as well as the positions of the objects captured in the images. This is called structure from motion (SfM) or visual simultaneous localisation and mapping (SLAM). In this thesis we present studies on how to create such maps, divided into three parts: to find accurate measurements; robust mapping; and merging of maps.The first part is treated in Paper I and involves finding precise – on a subsample level – TDOA measurements. These types of subsample refinements give a high precision, but are sensitive to noise. We present an explicit expression for the variance of the TDOA estimate and study the impact that noise in the signals has. Exact measurements is an important foundation for creating accurate maps. The second part of this thesis includes Papers II–V and covers the topic of robust self-calibration using one-dimensional signals, such as sound or radio. We estimate both sender and receiver positions using TOA and TDOA measurements. The estimation process is divided in two parts, where the first is specific for TOA or TDOA and involves solving a relaxed version of the problem. The second step is common for different types of problems and involves an upgrade from the relaxed solution to the sought parameters. In this thesis we present numerically stable minimal solvers for both these steps for some different setups with senders and receivers. We also suggest frameworks for how to use these solvers together with RANSAC to achieve systems that are robust to outliers, noise and missing data. Additionally, in the last paper we focus on extending self-calibration results, especially for the sound source path, which often cannot be fully reconstructed immediately. The third part of the thesis, Papers VI–VIII, is concerned with the merging of already estimated maps. We mainly focus on maps created from image data, but the methods are applicable to sparse 3D maps coming from different sensor modalities. Merging of maps can be advantageous if there are several map representations of the same environment, or if there is a need for adding new information to an already existing map. We suggest a compact map representation with a small memory footprint, which we then use to fuse maps efficiently. We suggest one method for fusion of maps that are pre-aligned, and one where we additionally estimate the coordinate system. The merging utilises a compact approximation of the residuals and allows for deformations in the original maps. Furthermore, we present minimal solvers for 3D point matching with statistical deformations – which increases the number of inliers when the original maps contain errors

    Rapid high-resolution mid-IR imaging for molecular spectral histopathological diagnosis of oesophageal cancers

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    This thesis is written as part of Marie-Curie international training network called Mid-TECH. Mid-TECH is devoted to improve mid-infrared (MIR) technologies and consists of 15 PhD projects across European universities. This thesis aims to evaluate new technologies and concepts developed by the project partners for their applicability in a biomedical setting. The clinical problem to diagnose oesophageal cancers serves as an example case for this. The thesis consists of three projects all aimed to further the understanding of MIR hyperspectral imaging. The first project discussed in chapter 5 demonstrates the use of an new design of the United States Airforce resolution test chart. The new test chart is developed to evaluate spatial resolution of MIR hyperspectral imaging systems. The use of different materials is discussed and the new iteration of the thes chart is evaluated using a state of the art MIR imaging system. The second project discussed in chapter 6 evaluates the technical differences and their practical implications of discrete frequency MIR imaging systems compared to continuum source systems. A comparison of the two system types is drawn for imaging paraffin embedded sections of oesophageal tissue. Furthermore the effect of chemically removing the paraffin from the sample is compared to a mathematical correction algorithm. The system performance is compared based on their ability to differentiate healthy from cancerous tissue. The third project discussed in chapter 7 evaluates the potential of a new MIR detection scheme called upconversion in combination with a novel MIR laser source. It is a prove of concept study demonstrating that those two technologies can be deployed to do hyperspectral imaging in the MIR.European Commissio

    Calibration of Linear Imager Camera for Relative Pose Estimation

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    The process of camera calibration is of paramount importance in order to employ any vision based sensor for relative navigation purposes. Understanding and quantifying the physical process that converts the external electromagnetic stimulus into an image inside a camera is key to relating the position of a body in an image to its pose in the real world. Both camera calibration and relative navigation are extensively explored topics. In the topic of camera calibration, various algorithms have been proposed that model the image formation process in different ways. This research utilizes the Homography approach proposed by Zhang [1] along with two distortion models: Brown’s nonlinear Distortion Model and the Geometric Distortion Model in order to model the intrinsic distortion and discrete image formation process. The idea of this research is to utilize the intrinsic parameters estimated using the homography optimization approach for the estimation of the relative pose of an object in the camera’s field of view. A nonlinear optimization based approach is presented for this purpose. The camera used here is the Phasespace Motion Capture camera [2] which utilizes linear imagers to form a fictitious image plane. Hence, the applicability of the two distortion models is tested through multiple datasets. Through testing with three datasets, it is found that neither distortion model is adequate to describe the distortion and image formation process in the Phasespace camera. A further test is conducted in order to validate the efficacy of the optimization based approach for relative pose estimation

    Abstracts - SA Heart Congress 2016

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    Index of abstracts: alphabetical listing of first authors

    On-belt Tomosynthesis: 3D Imaging of Baggage for Security Inspection

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    This thesis describes the design, testing and evaluation of `On-belt Tomosynthesis' (ObT): a cost-e ective baggage screening system based on limited angle digital x-ray tomosynthesis and close-range photogrammetry. It is designed to be retro tted to existing airport conveyor-belt systems and to overcome the limitations of current systems creating a pseudo-3D imaging system by combining x-ray and optical imaging to form digital tomograms. The ObT design and set-up consists of a con guration of two x-ray sources illuminating 12 strip detectors around a conveyor belt curve forming an 180 arc. Investigating the acquired ObT x-ray images' noise sources and distortions, improvements were demonstrated using developed image correction methods. An increase of 45% in image uniformity was shown as a result, in the postcorrection images. Simulation image reconstruction of objects with lower attenuation coe cients showed the potential of ObT to clearly distinguish between them. Reconstruction of real data showed that objects of bigger attenuation di erences (copper versus perspex, rather than air versus perspex) could be observed better. The main conclusion from the reconstruction results was that the current imaging method needed further re nements, regarding the geometry registration and the image reconstruction. The simulation results con rmed that advancing the experimental method could produce better results than the ones which can currently be achieved. For the current state of ObT, a standard deviation of 2 mm in (a) the source coordinates, and 2 in (b) the detector angles does not a ect the image reconstruction results. Therefore, a low-cost single camera coordination and tracking solution was developed to replace the previously used manual measurements. Results obtained by the developed solution showed that the necessary prerequisites for the ObT image reconstruction could be addressed. The resulting standard deviation was of an average of 0.4 mm and 1 degree for (a) and (b) respectively
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