Over the last ten years, terahertz (THz or T-ray) biomedical imaging has become a modality of interest due to its ability to simultaneously acquire both image and spectral information. Terahertz imaging systems are being commercialized, with increasing trials performed in a biomedical setting. Advanced digital image processing algorithms are greatly need to assist screening, diagnosis, and treatment. Pattern recognition algorithms play a critical role in the accurate and automatic process of detecting abnormalities when applied to biomedical imaging. This goal requires classification of meaningful physical contrast and identification of information in images, for example, distinguishing between different biological tissues or materials. T-ray tomographic imaging and detection technology contributes especially to our ability to discriminate opaque objects with clear boundaries and makes possible significant potential applications in both in vivo and ex vivo environments. The Thesis consists of a number of Chapters, which can be grouped in to three parts. The first part provides a review of the state-of-the-art regarding THz sources and detectors, THz imaging modes, and THz imaging analysis. Pattern recognition forms the second part of this Thesis, which is represented via combining several basic operations: wavelet transforms and wavelet based signal filtering, feature extraction and selection, along with classification schemes for THz applications. Signal filtering in this Thesis is achieved via wavelet based de-noising. The ultrafast pulses generated terahertz time-domain spectroscopy (THz-TDS), which is demonstrated to justify their decomposition in the wavelet domain as it can provide better de-noising performance. Feature extraction and selection of the terahertz measurements rely on observed changes in pulse amplitude and phase, as well as scattering characteristics of several different types of powder samples under study. Additionally, three signal processing algorithms are adopted for the evaluation of the complex insertion loss function of such samples as lactose, mandelic acid, and dl-mandelic acid: (i) standard evaluation by ratioing the sample with the background spectra, (ii) a subspace identification algorithm, and (iii) a novel wavelet packet identification procedure. These system identification algorithms enable THz measurements to be transformed to features for THz pattern recognition. Meanwhile, a novel feature extraction method involving the use of Auto Regressive (AR) and Auto Regressive Moving Average (ARMA)models on the wavelet transforms of measured T-ray pulse responses of ex vivo osteosarcoma cells as well as other biomedical materials is presented. Classification schemes are carried out via simple and robust schemes, such as the linear Mahalanobis distance classifier, and the non-linear Support Vector Machine (SVM) classifier. In particular, SVMs are used as a learning scheme to achieve the identification of two classes of RNA samples and multiple classes of powered materials. Coherent terahertz detection hardware—THz time-domain spectroscopy (THz-TDS)—is used to obtain all the data for validation of these classification schemes. The past decade has witnessed the tremendous development of terahertz instruments for detecting, storing, analysing, and displaying images. Terahertz time-domain spectroscopy (THz-TDS) is a broadband technique that generates and detects THz radiation in a synchronous and coherent manner. By contrast, the newly developed THz quantum cascade laser is a narrow-band radiation source that provides potential for realising compact systems; they produce image data with higher average power levels. The third part of this Thesis discusses methods to improve the capability of both broad and narrow-band terahertz imaging, driven by computer-aided analytical techniques. A wavelet based reconstruction algorithm for terahertz computed tomography is represented to show how this algorithm can be used to rapidly reconstruct the region of interest (ROI) with a reduction in the measurements of terahertz responses, compared with a standard filtered back-projection technique. These reconstruction algorithms are applied to the analysis of acquired experimental data and to locally recover the two dimensional (2D) and three-dimensional (3D) structures of several optically opaque objects. Moreover, a segmentation technique based on two dimensional wavelet transforms is investigated for the identification of different materials from the reconstructed CT image. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1352839 / Thesis (Ph.D.) - University of Adelaide, School of Electrical and Electronic Engineering, 2009

Introdução:embora seja mundialmente conhecida a correlação entre os escores tomográficos de avaliação isquêmica cerebral com achados e desfechos clínicos em pacientes com acidente vascular cerebral (AVC) isquêmico, são limitadas as evidencias em pacientes do subtipo cardioembólico. Objetivo: avaliar e correlacionar o perfil e desfechos clínicos de pacientes com AVC isquêmico do subtipo cardioembólico com os achados tomográficos de isquemia, segundo escores tomográficos. Métodos:estudo retrospectivo de um grupo de pacientes com AVC do tipo cardioembólico segundo a classificação TOAST, selecionados através de uma amostra de conveniência dos pacientes que foram atendidos em um centro de referência de emergências cerebrovasculares (março de 2014 a março de 2015). Os exames tomográficos destes pacientes foram avaliados por dois observadores (um radiologista com 10 anos e outro com 2 anos de experiência em exames tomográficos) treinados na avaliação de escores tomográficos relacionados a alterações isquêmicas encefálicas e cegados para os dados clínicos e laboratoriais dos pacientes. A análise estatística correlacionou os achados clínicos que incuíram fatores e preditores de risco, bem como transformação hemorrágica com os escores tomográficos que avaliam a isquemia cerebral. Resultados:o grupo com escore ASPECTS ≤7 apresentou significativamente maior uso de antiarrítmico, exclusão de trombólise, maior NIHSS, escala Rankin em 24h mais elevada e mais dias de internação quando comparado ao ASPECTS >7. Os pacientes com transformação hemorrágica apresentaram proporção significativamente maior de escore ASPECTS ≤ 7, mais do que um terço de acometimento do território da artéria cerebral média e AVC maior considerado pelo escore BASIS. Conclusão:os pacientes avaliados com AVC isquêmico cardioembólico que apresentaram transformação hemorrágica têm valores piores nos escores tomográficos de isquemia, com NHISS mais elevado e maior número de dias de internação. Houve uma correlação positiva entre o escore ASPECTS e os escores tomográficos regra de um terço e BASIS. / Introduction: although known worldwide, the correlation between tomographic cerebral ischemia evaluation scores and clinical outcome in patients with ischemic cerebral vascular accident (CVA), the evidences on patients with cardioembolic subtype are limited. Objective: evaluate and correlate the profile and clinical outcomes of patients with embolic subtype ischemic CVA with ischemia tomographic findings, according to tomographic scores. Methods: retrospective study of a patients group with cardioembolic subtype CVA according to TOAST classification, selected through a convenience sample from the patients that were treated at the cerebral vascular disease reference center emergency, (March 2014 to March 2015). These patients tomographic exams were evaluated by two observers (a radiologist with 10 years of expertise and another with 2 years of expertise in tomographic exams) trained in the assessment of tomographic scores related to encephalic ischemia alterations and blinded for the patients clinical and laboratorial data. The statistical analysis correlated the clinical findings, which included risk factors and predictors, as well as hemorrhagic transformation with the tomographic scores that evaluate cerebral ischemia. Results: groups with ASPECTS score ≤7 presented significantly higher use of antiarrhythmics, thrombolysis exclusion, higher NIHSS, higher 24 hours Rankin scale and more days of hospitalization when compared to ASPECTS >7. Patients with hemorrhagic transformation presented a significantly higher proportion of ASPECTS score ≤7. Conclusion: evaluated patients with cardioembolic ischemic CVA that had hemorrhagic transformation have worse tomographic ASPECTS score for ischemia, with higher NHISS and more hospitalization days. There was positive correlation between ASPECTS score and one third rule and BASIS tomographic scores.

Introdução:embora seja mundialmente conhecida a correlação entre os escores tomográficos de avaliação isquêmica cerebral com achados e desfechos clínicos em pacientes com acidente vascular cerebral (AVC) isquêmico, são limitadas as evidencias em pacientes do subtipo cardioembólico. Objetivo: avaliar e correlacionar o perfil e desfechos clínicos de pacientes com AVC isquêmico do subtipo cardioembólico com os achados tomográficos de isquemia, segundo escores tomográficos. Métodos:estudo retrospectivo de um grupo de pacientes com AVC do tipo cardioembólico segundo a classificação TOAST, selecionados através de uma amostra de conveniência dos pacientes que foram atendidos em um centro de referência de emergências cerebrovasculares (março de 2014 a março de 2015). Os exames tomográficos destes pacientes foram avaliados por dois observadores (um radiologista com 10 anos e outro com 2 anos de experiência em exames tomográficos) treinados na avaliação de escores tomográficos relacionados a alterações isquêmicas encefálicas e cegados para os dados clínicos e laboratoriais dos pacientes. A análise estatística correlacionou os achados clínicos que incuíram fatores e preditores de risco, bem como transformação hemorrágica com os escores tomográficos que avaliam a isquemia cerebral. Resultados:o grupo com escore ASPECTS ≤7 apresentou significativamente maior uso de antiarrítmico, exclusão de trombólise, maior NIHSS, escala Rankin em 24h mais elevada e mais dias de internação quando comparado ao ASPECTS >7. Os pacientes com transformação hemorrágica apresentaram proporção significativamente maior de escore ASPECTS ≤ 7, mais do que um terço de acometimento do território da artéria cerebral média e AVC maior considerado pelo escore BASIS. Conclusão:os pacientes avaliados com AVC isquêmico cardioembólico que apresentaram transformação hemorrágica têm valores piores nos escores tomográficos de isquemia, com NHISS mais elevado e maior número de dias de internação. Houve uma correlação positiva entre o escore ASPECTS e os escores tomográficos regra de um terço e BASIS. / Introduction: although known worldwide, the correlation between tomographic cerebral ischemia evaluation scores and clinical outcome in patients with ischemic cerebral vascular accident (CVA), the evidences on patients with cardioembolic subtype are limited. Objective: evaluate and correlate the profile and clinical outcomes of patients with embolic subtype ischemic CVA with ischemia tomographic findings, according to tomographic scores. Methods: retrospective study of a patients group with cardioembolic subtype CVA according to TOAST classification, selected through a convenience sample from the patients that were treated at the cerebral vascular disease reference center emergency, (March 2014 to March 2015). These patients tomographic exams were evaluated by two observers (a radiologist with 10 years of expertise and another with 2 years of expertise in tomographic exams) trained in the assessment of tomographic scores related to encephalic ischemia alterations and blinded for the patients clinical and laboratorial data. The statistical analysis correlated the clinical findings, which included risk factors and predictors, as well as hemorrhagic transformation with the tomographic scores that evaluate cerebral ischemia. Results: groups with ASPECTS score ≤7 presented significantly higher use of antiarrhythmics, thrombolysis exclusion, higher NIHSS, higher 24 hours Rankin scale and more days of hospitalization when compared to ASPECTS >7. Patients with hemorrhagic transformation presented a significantly higher proportion of ASPECTS score ≤7. Conclusion: evaluated patients with cardioembolic ischemic CVA that had hemorrhagic transformation have worse tomographic ASPECTS score for ischemia, with higher NHISS and more hospitalization days. There was positive correlation between ASPECTS score and one third rule and BASIS tomographic scores.

Nesta tese é apresentado um novo método de reconstrução de imagens, por tomografia de transmissão, de projeções sujeitas a ruído na contagem de fótons. O método de reconstrução selecionado utiliza a técnica POCS (Projections Onto Convex Sets). A estimação das projeções originais a partir das observações ruidosas se dá por meio de quatro métodos: a) estimação utilizando o critério MAP (Maximum a Posteriori); b) filtragem nos coeficientes wavelets das projeções ruidosas; c) aplicação do filtro de Wiener pontual e d) aplicação do filtro de Goodman-Belsher. É apresentado o resultado da reconstrução após a estimação das projeções, mostrando o ISNR (Improvement Signal-to-Noise Ratio) entre as imagens reconstruídas, a partir das projeções ruidosas, com a técnica POCS, estimando as projeções e sem a realização da estimação. Foram utilizados, para reconstrução tomográfica, projeções de corpos de prova obtidos por meio de simulação e também projeções obtidas experimentalmente no minitomógrafo do CNPDIA - EMBRAPA. O uso de estimação sobre as projeções ruidosas mostrou-se eficaz para melhorar a relação sinal-ruído na imagem final, pois esse pré-processamento faz com que os conjuntos impostos pelas projeções sejam mais restritivos. Deve-se observar que a melhoria das imagens obtidas com o uso de filtragem das projeções é obtida com uma relação custo-benefício bastante baixa, pois a maior parte do custo computacional está na fase de reconstrução das imagens. / In this thesis is pesented a new method for image reconstruction, by transmission tomography, for projections under noise in the counting of photons. The selected method of reconstruction uses the POCS (Projections Onto Convex Sets) technique. The estimation of the original projections from the noisy projections observed is performed through four methods: a) estimation using the MAP (Maximum a Posteriori) criteria; b) through of filtering of the wavelets coefficients of the noisy projections; c) using the pointwise Wiener filter and d) using the Goodman-Belsher filter. We present the result of reconstruction after projection estimation, showing the ISNR (Improvement Signal-to-Noise Ratio) between the reconstructed images on noisy projections, using POCS technique after the estimated projections and without this estimation. We use, for tomographic reconstruction, test body projections obtained through simulation and also projections obtained experimentally in the minitomograph scanner of CNPDIA-EMBRAPA. The use of estimation on noisy projections demonstrated to be efficient in improving the signalnoise ratio in the final image, since this pre-processing makes the sets that projections more restrictive. We should observe that the use of projection filtering is obtained with a cost-benefit ratio rather low, since the largest part of the computational effort is in the image reconstruction phase.

O diagnóstico precoce de focos de infecção dentários é de fundamental importância para prevenir a ocorrência de maiores injúrias locais ou sistêmicas. Dentre os diversos métodos utilizados para complementar os achados radiológicos das alterações dentoalveolares surge uma alternativa: a cintilografia tomográfica (SPECT/CT), que permite a fusão de achados morfológicos com alterações metabólicas. Com o objetivo de estabelecer o diagnóstico precoce e acurado de processos infecciosos dentários, foram estudadas 320 áreas dentárias em mandíbula e maxila em (10 pacientes de ambos os sexos selecionados por meio de exames clínicos e radiológicos convencionais, seguidos de cintilografia tomográfica com e sem aparato blindador de raios gama. Os exames cintilográficos foram realizados no Serviço de Medicina Nuclear do Hospital Israelita Albert Einstein (HIAE). Para isso, foi administrado para cada paciente o radiofármaco tecnécio 99- metilenodifosfonato (99mTc-MDP) via endovenosa com a dose de 37mBq/3Kg de peso corporal do paciente. Após o período de acúmulo de três horas, foi realizado o protocolo de aquisição de imagens. Todas as imagens foram analisadas por um médico nuclear e um endodontista, com experiência em cintilografia tomográfica. O resultado obtido por meio do exame radiográfico intrabucal pela técnica periapical digital mostraram 6 imagens positivas, em um total de 1,87% da amostra; exame do mapeamento cintilográfico dos ossos da face com a utilização do blindador de raios gâma revelou 9 imagens positivas, correspondendo a 2,81% do total de áreas estudadas, havendo diferença estatisticamente significante ao nível de 95% pelo teste qui-quadrado. Pode-se concluir que o SPECT/CT permitiu identificar as alterações periapicais em maior número quando comparadas ao exame radiográfico periapical e ao mapeamento cintilográfico dos ossos da face com a utilização do blindador de raios gama; o exame de SPCET/CT além de mostrar imagens mais detalhadas, permitiu também localizar com exatidão as áreas alteradas. / The early diagnosis of cases with dental infection is very important to prevent the occurrence of major local or systemic injuries. With many methods used to complement the radiological findings of the bone alterations there\'s the tomographic scintigraphy witch allows the fusion of morphological and metabolic findings. With the objective of the establishment of early diagnosis and accurate dental infectious processes, it was studied 320 dental areas in maxilla and mandible (10 patients) selected randomly, through conventional radiological exams, followed by tomographic scintigraphy with and without intra-oral apparatus. The scintilographic exams were done at the Nuclear Medicine Service of Hospital Israelita Albert Einstein. For that, methylenediphosphonate-technetium-99m (99mTc-MDP) was dispensed intravenous. After the period of accumulation of 3 hours, the image acquisition protocol was taken. This protocol includes images from the top of the head to the neck. After the image analyzes, statistics was done. The intrabucal radiograph exam by the digital periapical technique showed 6 positive images, in a total of 1.87% of the total sample, Intra-oral apparatus showed 9 positive images, in a total os 2,81% of the sample and SPECT/CT exam revealed 15 positive images, corresponding to 4.28% of the total studied areas, showing statistical significance by the level of 95% of qui-square. We could conclude that SPECT/CT allowed identifying the endodontic infections in a larger number when compared with the radiograph exams; and the SPECT/CT exam showed to be of great interest by allowing the union of the diagnosis precocity with the image detail, presenting exact localization of inflammatory/infectious alterations due to the presence of the CT.

O objetivo deste trabalho foi avaliar a influência das correções de atenuação e espalhamento na reconstrução quantitativa em SPECT. O estudo foi baseado em diversas simulações de Monte Carlo, com ênfase especial no modelo torso-cardíaco matemático (MCAT). Para a reconstrução, foi utilizado o algoritmo iterativo ML-EM com projetor-retroprojetor modificado pelo mapa de atenuação. Para avaliar a correção de espalhamento, foram simulados os espectros energéticos, com múltiplas ordens de espalhamento Compton. O método da dupla janela de energia (Jaszczak) foi aplicado, devido a sua simplicidade, e as imagens corrigidas foram comparadas com as de fótons primários. Foram analisadas as escolhas das janelas do fotopico e espalhamento, além da dependência do fator de espalhamento k com a distribuição de atividades do objeto. Duas abordagens foram adotadas para a obtenção dos mapas de atenuação: a estimativa do mapa uniforme diretamente dos dados de emissão, sem o uso de imagens de transmissão; e o borramento de mapas não-uniformes, reconstruídos a partir das projeções por transmissão. A estimativa do mapa de atenuação diretamente dos sinogramas de emissão baseou-se nas condições de consistência da transformada de Radon atenuada. Neste caso, foram estudados os efeitos de diferentes contagens e vários coeficientes de atenuação iniciais sobre as imagens corrigidas. Os mapas de atenuação não-uniformes foram borrados com um \"kernei\" gaussiano, aplicados nas correções e os efeitos na quantificação foram analisados. Os espectros energéticos emitidos pelo modelo MCAT mostraram que os fótons espalhados não poderiam ser excluídos a contento, mesmo que fossem utilizadas janelas de aquisição estreitas sobre o fotopico. Em relação a correção de Jaszczak, verificou-se que a escolha das janelas de fotopico e espalhamento é crucial e confirmou-se que o valor de k é altamente dependente do objeto examinado. Dada uma estimativa inicial do mapa de atenuação, o uso das condições de consistência para estimar o mapa de atenuação uniforme, consistente com os dados de emissão do modelo MCAT simulado, resultou sempre em uma mesma forma, para quaisquer valores iniciais do conjunto de parâmetros. Apesar do erro diminuir com o aumento da contagem, o melhor coeficiente de atenuação não pôde ser obtido, mesmo em altas contagens. Isto se deve a presença dos fótons espalhados, que alteraram a solução das condições de consistência, reduzindo as dimensões do mapa. Os resultados indicaram que a correção de espalhamento é o fator mais importante na reconstrução quantitativa em SPECT. Com referência aos efeitos quantitativos da correção de atenuação, não foram observadas diferenças significativas com a utilização dos mapas borrados, enquanto que a correção com mapas uniformes mostrou-se menos eficaz. / The goal of this work is to evaluate the influence of scatter and attenuation correction methods in quantitative SPECT reconstruction. The study was based on several Monte Carlo simulations, with special emphasis on the mathematical cardiac-torso phantom (MCAT). Iterative ML-EM reconstruction with modified projector-backprojector was used. To evaluate the scatter correction, energy spectra were simulated for SPECT imaging including multiple order Compton scattered photons. The dual energy window method proposed by Jaszczak was applied and scatter corrected images were compared with primary photons images. The choice of the scattering and photopeak windows and the dependence of the scatter factor k with the activity distribution were also analysed. Two approaches were adopted for obtaining the maps for attenuation correction: the estimation of the attenuation maps directly from the emission data, without transmission imaging, and the blurring of non-uniform attenuation maps, reconstructed from transmission data. The estimation of attenuation maps directly from the emission sinograms was based on the consistency conditions of attenuated Radon transform. In this case, the effects of different counting rates and various initial attenuation coefficients on the corrected images were studied. The non-uniform attenuation maps were blurred with a gaussian kernel with different variances, applied in further corrections and their effects on quantitation were examined. Analysis of energy spectra emitted from the MCAT phantom showed that scattered photons cannot be totally excluded, even when narrow acquisition windows were used. As far as the Jaszczak correction is concerned, results showed that the choice of photopeak and secondary windows is crucial and that the value of k is highly dependent on the imaged object. Given an initial estimation of the attenuation map with a constant coefficient, the use of consistency conditions to estimate the uniform map, consistent with the emission data of simulated MCAT phantom, resulted in the same shape for any set of initial parameters. In spite of the fact that the error falls with increasing counting rate, higher counts are not able to determine the best attenuation coefficient. This is due to scattered photons, which alter the solution of consistency conditions, reducing the size of estimated maps. Results indicated that the scatter correction is the most important factor inquantitative SPECT reconstruction. Furthermore, no significant differences were observed in the quantitation, when using the blurred non- uniform attenuation maps in attenuation correction, while corrections with uniform maps proved to be less efficient

Foram avaliados 25 cães portadores de discopatia cervical aos exames radiográficos simples, mielografia e tomografia computadorizada. A dor foi o principal sinal clínico em 64% dos casos. Os animais com raça definida foram os mais acometidos (85%), tendo maior incidência da raça Teckel. A faixa etária mais acometida foi entre 7-9 anos (72%). O exame radiográfico simples indicou aspectos compatíveis com extrusão em 14 observações. A mielografia diagnosticou 15 extrusões, 18 protrusões e 4 hérnias de disco e forneceu informações quanto ao grau de compressão medular e extensão das lesões. A tomografia computadorizada (TC) indicou 16 extrusões, 22 protrusões e 3 hérnias de disco. O espaço de C2-3 foi o mais acometido. A TC permitiu o diagnóstico de extrusões calcificadas, mesmo na presença de pouca quantidade ou ausência de meio de contraste e indicou com precisão o grau de compressão medular, a extensão e principalmente, a localização das lesões. Concluiu-se com este estudo que os três exames se complementam e constituem importantes ferramentas para o planejamento clínico-cirúrgico. / Twenty-five dogs with disc disease in cervical spine were evaluated by radiological and computed tomographic exams. The most common clinical signs were neck pain present in 64% of the dogs. Of the animals 85% were pure breed, amongst them Teckel were most frequent (28%). The most cases occurred in animals between seven and nine years. C2-3 was the preferred site of cervical involvement. Radiographic plain indicated fourteen extrusion. Myelography demonstrated fifteen extrusions, eighteen protrusions and four disc hernias and indicated spinal cord grade compression and lesions extension. Computed tomographic (CT) demonstred sixteen extrusions, twenty-two protrusions and three disc hernias. The CT showed to be more sensitive for soft tissue calcification, and his superior contrast resolution allowed visualization small quantities of contrast material in the subarachnoid space and indicated with precision the site and extension of lesions as well as the degree of spinal cord compression. The three exams are complementary and give valuable information for clinical and chirurgical procedures.

The turbulent boundary layer is an aspect of fluid flow which dominates the performance of many engineering systems - yet the analytic solution of such flows is intractable for most applications. Our understanding of boundary layers is therefore limited by our ability to simulate and measure them. Tomographic Particle Image Velocimetry (TPIV) is a recently developed technique for direct measurement of fluid velocity within a 3D region. This allows new insight into the topological structure of turbulent boundary layers. Increasing Reynolds Number increases the range of scales at which turbulence exists; a measurement technique must have a larger 'dynamic range' to fully resolve the flow. Tomographic PIV is currently limited in spatial dynamic range (which is also linked to the spatial and temporal resolution) due to a high degree of noise. Results also contain significant bias error. This work proposes a modification of the technique to use more than two exposures in the PIV process, which (for four exposures) is shown to improve random error by a factor of 2 to 7 depending on experimental setup parameters. The dynamic range increases correspondingly and can be doubled again in highly turbulent flows. Bias error is reduced by up to 40%. An alternative reconstruction approach is also presented, based on application of a reduction strategy (elimination of coefficients based on a first guess) to the tomographic weightings matrix Wij. This facilitates a potentially significant increase in computational efficiency. Despite the achieved reduction in error, measurements contain non-zero divergence due to noise and sampling errors. The same problem affects visualisation of topology and coherent fluid structures. Using Projection Onto Convex Sets, a framework for post-processing operators is implemented which includes a divergence minimisation procedure and a scale-limited denoising strategy which is resilient to 'false' vectors contained in the data. Finally, developed techniques are showcased by visualisation of topological information in the inner region of a high Reynolds Number boundary layer (δ+ = 1890, Reθ = 3650). Comments are made on the visible flow structures and tentative conclusions are drawn.

No description available.

The aim of this research is to explore the integration of ad hoc and mobile sensors into a conventional Electrical Resistance Tomography (ERT) system. This is motivated by the desire to improve the spatial resolution of 3D reconstructed images that are produced using ERT. The feasibility of two approaches, referred to as the Extended Electrical Tomography (EET) and Augmented Electrical Tomography (AET) are considered. The approaches are characterized according to the functionality of the sensors on the ad hoc 'pills'. This thesis utilizes spectral and numerical analysis techniques, with the goal of providing a better understanding of reconstruction limitations, including quality of measurements, sensitivity levels and spatial resolution. These techniques are applied such that an objective evaluation can be made, without having to depend heavily on visual inspection of a selection of reconstructed images when evaluating the performance of different set-ups. In EET, the sensors on the pills are used as part of the ERT electrode system. Localized voltage differences are measured on a pair of electrodes that are located on an ad hoc pill. This extends the number of measurements per data set and provides information that was previously unobtainable using conventional electrode arrangements. A standalone voltage measurement system is used to acquire measurements that are taken using the internal electrodes. The system mimics the situation that is envisaged for a wireless pill, specifically that it has a floating ground and is battery-powered. For the present exploratory purposes, the electronic hardware is located remotely and the measured signal is transmitted to the PC through a cable. The instrumentation and data acquisition circuits are separated through opto-isolators which essentially isolates both systems. Using a single pill located in the centre of a vessel furnished with 16 electrodes arranged in a single plane, spectral analysis indicates that 15 of the 16 extended measurements acquired using the adjacent current injection strategy are unique. Improvement is observed for both the sensitivity and spatial resolution for the voxels in the vicinity of the ad hoc pill when comparing the EET approach with the conventional ERT approach. This shows the benefit of the EET approach. However, visual inspection of reconstructed images reveals no apparent difference between images produced using a regular and extended dataset. Similar studies are conducted for cases considering the opposite strategy, different position and orientation of the pill, and the effect of using multiple pills. In AET, the sensors on the ad hoc pills are used as conductivity probes. Localized conductivity measurements provide conductivity values of the voxels in a discretized mesh of the vessel, which reduces the number of unknowns to be solved during reconstruction. The measurements are incorporated into the inverse solver as prior information. The Gauss-Newton algorithm is chosen for implementation of this approach because of its non-linear nature. Little improvement is seen with the inclusion of one localized conductivity measurement. The effect on the neighbouring voxels is insignificant and there is a lack of control over how the augmented measurement influences the solution of its neighbouring voxels. This is the first time that measurements using ad hoc and 'wireless' sensors within the region of interest have been incorporated into an electrical tomography system.