467 research outputs found

    Alpha particle transport in voxelized trabecular bone images

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    Alpha particles are of current interest in radionuclide therapy due to their short range and high rates of energy transfer to target tissues. Published values of alpha-particle absorbed fractions in skeletal tissues do not vary with particle energy, cellularity or skeletal site. To correct for this, absorbed fractions are calculated using Monte Carlo techniques in 3D voxelized images. In this study absorbed fraction values are acquired for deep marrow (TAM), shallow marrow (TAMS), and trabecular bone volume (TBV) targets for a broad energy spectrum of alpha particles originating in the TAM, TAMs, and TBV of 33 voxelized images. Additionally the impact of marrow cellularity on absorbed fraction is investigated, by varying the fat percentage from 0% to 100% for each bone site; Calculated absorbed fractions show an energy dependence for all source-target combinations. Additionally, AF(TAM←TAM) is greatly influenced by marrow cellularity. These dependencies on energy and cellularity illustrate the weaknesses in the current ICRP methodology.*; *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Adobe Acrobat

    Evidence of diet, deification, and death within ancient Egyptian mummified animals

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    The clues to life and death of mummified animals can remain hidden beneath their wrappings. Developments in non-invasive imaging have enabled detailed study of their internal structures. Laboratory-based X-ray microcomputed tomography (microCT) and focussed imaging protocols permit smaller mummified remains, such as animals, to be studied at higher resolution. In this study, we use microCT to image three different animal mummies. Revealing the internal structures provides insights into their biography, the conditions in which they were kept, complex mummification practices, possible causes of death, and subsequent handling damage. Thousands of years after the production of these mummified animals, the X-ray microCT technique facilitates new investigations, revealing ‘harder’ skeletal structures, mummification materials, and even desiccated soft tissues. Potential evidence for an ‘opening of the mouth’ procedure was found in a snake, along with indicators of the poor conditions in which the snake was kept when alive, leading to dehydration. Examination of a cat mummy revealed it was less than five months old and had its neck purposefully broken. It was also possible to identify a bird mummy to species level from the X-ray data. Improved understanding of animal mummification through scientific imaging can thus inform conservation and understanding of past human-animal relationships

    Gender determination based on ct cranium measurements of adults in Hospital USM

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    Purpose: The purpose of this study was to determine gender based on cranial measurements using Computed Tomography of adult. This study has not yet been done in this population. The measurements include the Glabello- Occipital Length (GOL), Basion- Nasion Length (BNL), Basion- Bregma length (BBL), Nasion- Bregma cord i.e. Frontal Chord (FRC), Bregma- Lambda i.e. Parietal Chord (PAC), Lambda- Opisthion i.e. Occipital Chord (OCC), Diploeic space 1 cm in front of the Bregma (DBB) and 1 cm behind lambda (DBL). Methods: A sample size of 180 adult patients in Hospital Universiti Sains Malaysia who underwent CT head were included in this study. The age taken was between the range of 18 years old and above. Images were reviewed in bone window. Results: The mean of glabello-occipital length, basion-nasion length, basion-bregma length, nasion - Bregma cord, Bregma- Lambda, Lambda- Opisthion and Diploeic space 1cm below lambda were statistically different between male and female. There was positive linear relationship for Glabello- Occipital Length, Basion- Bregma Length and Nasion Bregma cord between height and weight. Meanwhile Basion- Nasion Length only has a significant relationship with height. Conclusion: For this population, this study as well as other studies support for correlation in between certain cranial morphometry measurements with gender, height and weight. Thus, it might help to assist the future forensic radiology medicine using CT cranium to determine the gender, height and weight of patient or deceased

    Exploring the Sinonasal Cavity in Three Dimensions: Teaching Otolaryngology Surgical Trainees Clinical Anatomy Using a Web-based Learning Resource

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    Endoscopic sinus surgery is the most common procedure to restore normal sinus function in chronic sinus disease and is performed in a small complex anatomical space intimate to critical structures (i.e. eyes, anterior cranial fossa, and major head and neck vessels). Otolaryngology surgical trainees must therefore have a thorough three-dimensional (3D) understanding of the sinonasal space to avoid disorientation when surgically navigating through a limited endoscopic view. However, learning of this anatomical region is hampered by the complexity of anatomy as well as limitations in current teaching resources. Commonly used two-dimensional (2D) visualizations include static illustrations and radiological CT imaging that poorly convey the 3D nature of the space. The author could not find any existing educational resources employing 3D visualization of the sinonasal space. Web-based multimedia resources, such as online sinus surgery videos are widely used as a learning tool with novel clinical training modules developed to facilitate correlation of anatomical knowledge in radiological visualization and endoscopic surgical view. However, these resources lack correlation among the different types of media and the spatial relationships of clinically relevant structures in 3D space is not fully correlated to static 2D visualizations. In this project, we propose creating a web-based interactive resource offering a comprehensive and multidimensional visualization of the sinonasal cavity. This resource will consist of two learning modes: i) In Explore Mode, fully interactable 3D schematic and CT-segmented models are presented alongside 2D axial and coronal CT image series, allowing users to navigate the sinonasal cavity in 3D space and bridge the gap between 3D and 2D visualizations. ii) In Clinical Mode, surgical video clips are featured in addition to a schematic 3D model and CT image series, improving spatial orientation during surgery by correlating 3D and 2D visualizations of the sinonasal cavity from a clinical perspective. The authors of this research postulate such a resource can improve clinical training outcomes among otolaryngology surgical trainees

    The design and manufacture of an anthropomorphic head phantom using direct digital manufacturing techniques

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    Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Engenharia Clínica e Instrumentação Médica) Universidade de Lisboa, Faculdade de Ciências, 2020Positron emission tomography images are used to obtain in vivo qualitative measurements of physiological parameters. Partial volume effects, by effectively blurring the images, harms this quantitativenature. Phantoms can be used to both evaluate how blurred are the images produced by a positron emission tomography system as well as correct for them, by providing a way to obtain a function that maps how this blur across the images. This function can then be used to remove partial volume effects artifacts. The aim of this study was to develop an anthropomorphic head phantom, with brain and skull structures, to help with the aforementioned tasks, since it will provide a more accurate simulation of real subjects. To build a phantom with structures as complex as grey and white matter and the skull, 3d printing techniques were used. The models were obtained from magnetic resonance images using seeded region growing algorithms. The segmented models obtained had the basic structure of the target tissues except for the grey matter model which ended up incomplete. Due to this and failure to design a robust brain phantom we were only able to print the cranium portion of the head phantom, and due to the very long print time required, even of this only a small part was printed. This is the beginning of the project and although a full phantom has not been created we showed that, after some optimizations, it is viable to print a realistic skull phantom, using a polycaprolactonehydroxyapatitemisture that mimics bone’s radiological properties.Imagens de Positron Emission Tomography (PET) são obtidas detetando a distribuição e concentração de um radiofármaco nos tecidos de um sujeito. Radiofármacos são moléculas que no organismo se comportam de modo semelhante a alguma outra molécula que participe num processo fisiológico, de modo a que estas possam tomar o seu lugar. Em adição, são dopadas com elementos radioactivos de modo a que a sua distribuição monitorizada. Ao escolher um radioisótopo somos então capazes de quantificar o processo fisiológico no qual este participa. A glucose, por exemplo, é utilizada para quantificar a intensidade de procesos metabólicos. Os radioisótopos irão emitir positrões que irão interagir com os tecidos para gerar um par de fotõs que irão viajar em direções opostas. Durante o processo de construção da imagem são as deteções destes pares de fotões que são utilizadas. Ao atravessar um meio, existe uma probabilidade destes fotões serem absorvidos. Quanto mais denso o meio, maior esta probablidade. No corpo humano, ao cruzar estruturas mais ou menos densas, ossos e pulmões, por exemplo, a quantidade de eletrões atenuados irá variar, distorcendo as imagens geradas. Ao fazer um scan de Computed Tomography (CT), podemos obter um mapa da atenuação das estruturas que é utilizado para corrigir estes efeitos. Efeitos de volumes parciais (PVE) fazem com que as imagens geradas pareçam algo desfocadas. Estes efeitos têm 2 origens: 1) Como os positrões emitidos pelos radiofármacos têm sempre de atravessar alguma matéria até originarem o par de fotões que será detetado. Até uma distribuição pontual de radiofármaco será observada como um volume. 2) Como os sensores têm uma resolução espacial limitada, os píxeis correspondentes a fronteiras entre duas estruturas irão conter informação misturada das duas. Isto faz com que as fronteiras entre regiões não sejam tão nítidas. Para vários tratamentos é importante avaliar quantitavimanente certos parâmetros fisiológicos. Por exemplo, é possível avaliar a resposta de um tumor a tratamentos através da sua taxa metabólica, que podemos quantizar com imagens de PET. Infelizmente efeitos de PVE, afetam a precisão destas medidas, ao desfocar as imagens. Torna-se então importante estudar estes efeitos, como os reduzir e avaliar o seu efeito nos vários sistemas de imagem. Para testar e avaliar a qualidade das imagens geradas por equipamentos PET e o quão fielmente representam a realidade são usados fantomas, objectos que tentam representar o corpo humano, de modo a evitar a exposição de pacientes a estes processos desnecessariamente. Existe ainda a vantagem de sabermos exatamente o resultado esperado para as imagens. Regra geral, estes fantomas correspondem a versões muito simplistas da realidade, recorrendo a formas geométricas simples como retângulos e esferas. O objectivo deste trabalho é desenvolver um fantoma antropomórfico, com estruturas realistas, do cérebro e crânio utilizando tecnologias de impressão 3d para avaliar a performance de equipamentos de PET/CT. Para obter modelos realistas que podemos passar a uma impressora 3d recorremos à segmentação de imagens de ressonância magnética e CT utilizando algoritmos seeded region growing. Estes algoritmos pegam num ponto inicial (semente), com o qual comparam os valores dos píxeis vizinhos. Caso a diferença de intensidades entre os píxeis vizinhos e a média da região que está a ser segmentada seja menor que um limite pré-definido, estes são acrescentados à região segmentada. É através deste limite e das sementes iniciais que variamos os resultados da segmentação. Este algoritmo em particular adequasse a esta tarefa uma vez que as regiões correspondentes às matérias branca e cinzenta têm contornos complexosmas com baixa variação de intensidade dos píxeis no seu interior. Tentámos aplicar o mesmo algoritmo para segmentar o crânio e o cérebro. Devido à estrutura do osso do crânio, esponjoso (logo menos denso) no centro fomos capazes de segmentar o seu contorno corretamente à custa de uma maior espessura deste. Quanto ao cérebro, apesar da matéria branca e ventrículos terem sido corretamente segmentados, a matéria cinzenta, que neste contexto pode ser vista como uma camada ao redor da matéria branca, possui várias zonas onde é inexistente. Nestas, ou se apresenta como matéria branca ou não existe de todo. Utilizámos os modelos da matéria branca e cinzenta para remover o excesso do modelo do crânio e, de seguida, dividimos este modelo em múltiplas peças que a impressora à nossa disposição é capaz de imprimir. Para o fantoma do cérebro tentámos apenas recriar uma região oca correspondendo à matéria cinzenta. Para tal dilatámos o modelo da matéria cinzenta, de modo a obter a parede exterior deste e utilizámos o modelo da matéria branca para obter a sua parede interior. Esta abordagem gerou uma câmara oca correspondente à matéria cinzenta com uma espessura muito inferior ao esperado e que, em certas regiões era até inexistente (devido aos modelos utilizados). Um problema maior, no entanto, é que esta abordagem não teve em conta a robustez mecânica do fantoma, não tendo estruturas de suporte nem podendo garantir uma forma eficaz de encher e vazar o fantoma com os radiofármacos de modo a testá-lo. Assim sendo apenas avançamos para a fase de impressão 3d do modelo do crânio. De modo a que o fantoma do crânio se comporte de modo semelhante ao osso (em relação às suas propriedades imagiológicas), criámos uma mistura de policaprolactona (PCL) e hidroxiapatita (HA) em proporção de 50%. Para imprimir a peça utilizámos uma impressora 3d feita por medida que nos permite personalizar os materiais com os quais queremos imprimir. Utilizámos um bocal de 0:3mm que apesar de permitir maior detalhe exige um grande número de passagens para gerar cada camada da peça. Estimámos que, para imprimir todas as pecas do crânio, demoraríamos cerca de 5 meses pelo que apenas imprimimos uma única parte. A peça que imprimimos demontra que é possível utilizar a impressora BIOMATE para este tipo de trabalhos uma vez que mesmo sem material de suporte fomos capazes que obter estruturas como arcos e rampas, necessárias para a impressão de estruturas complexas, apesar de ser necessário referir que não de forma perfeita. Será necessário continuar a optimizar o processo, em particular tentar minimizar deformações geradas enquanto camadas já impressas arrefecem durante o processo de impressão. Apesar de não termos concretizado todos os objetivos a que nos propusemos temos agora uma ideia melhor de onde concentrar os nossos esforços: Obter boas imagens nas quais basearemos a segmentação; Perceber a melhor forma de passar de um modelo do cérebro para uma estrutura oca do fantoma que permitirá o fluxo de radiofármaco e Possiveis formas de expeditar o processo de impressão

    An Image-Based Computational System for the Design of Radionuclide Therapies for Skeletal Tumors

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    Development of the VHP-Female CAD model including Dynamic Breathing Sequence

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    Mathematics, physics, biology, and computer science are combined to create computational modeling, which studies the behaviors and reactions of complex biomedical problems. Modern biomedical research relies significantly on realistic computational human models or “virtual humans�. Relevant study areas utilizing computational human models include electromagnetics, solid mechanics, fluid dynamics, optics, ultrasound propagation, thermal propagation, and automotive safety research. These and other applications provide ample justification for the realization of the Visible Human Project® (VHP)-Female v. 4.0, a new platform-independent full body electromagnetic computational model. Along with the VHP-Female v. 4.0, a realistic and anatomically justified Dynamic Breathing Sequence is developed. The creation of such model is essential to the development of biomedical devices and procedures that are affected by the dynamics of human breathing, such as Magnetic Resonance Imaging and the calculation of Specific Absorption Rate. The model can be used in numerous application, including Breath-Detection Radar for human search and rescue

    An investigation into 3D printing of osteological remains: the metrology and ethics of virtual anthropology

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    Three-dimensional (3D) printed human remains are being utilised in courtroom demonstrations of evidence within the UK criminal justice system. This presents a potential issue given that the use of 3D replicas has not yet been empirically tested or validated for use in crime reconstructions. Further, recent movements to critically evaluate the ethics surrounding the presentation of human remains have failed to address the use of 3D printed replica bones. As such, this research addresses the knowledge gap surrounding the accuracy of 3D printed replicas of skeletal elements and investigates how the public feels about the use of 3D printed replicas. Three experimental studies focussed on metrology and identified 3D printed replicas to be accurate to within ± 2.0 mm using computed tomography (CT) scanning, and to within ± 0.2 mm or to 0-5% difference using micro-CT. The potential loss of micromorphological details was also examined and identified that quality control steps were key in identifying and mitigating loss of detail. A fourth experimental study collected data on the opinion of the public of the use of 3D printed human remains in courtroom demonstrations. Respondents were broadly positive and considered that prints can be produced ethically by maintaining the dignity and respect of the decedent. A framework that helps to assess ethical practices was developed as well as an adaptable pathway that can assist with assessing the quality and accuracy of 3D prints. The findings from this research contribute to an empirical evidence base that can underpin future 3D printed crime reconstructions and provides guidance for creating accurate 3D prints that can inform future practice and research endeavours

    Spherical harmonics to quantify cranial asymmetry in deformational plagiocephaly

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    [EN] Cranial deformation and deformational plagiocephaly (DP) in particular affect an important percentage of infants. The assessment and diagnosis of the deformation are commonly carried by manual measurements that provide low interuser accuracy. Another approach is the use of three-dimensional (3D) models. Nevertheless, in most cases, deformation measurements are carried out manually on the 3D model. It is necessary to develop methodologies for the detection of DP that are automatic, accurate and take profit on the high quantity of information of the 3D models. Spherical harmonics are proposed as a new methodology to identify DP from head 3D models. The ideal fitted ellipsoid for each head is computed and the orthogonal distances between head and ellipsoid are obtained. Finally, the distances are modelled using spherical harmonics. Spherical harmonic coefficients of degree 2 and order - 2 are identified as the correct ones to represent the asymmetry characteristic of DP. The obtained coefficient is compared to other anthropometric deformation indexes, such as Asymmetry Index, Oblique Cranial Length Ratio, Posterior Asymmetry Index and Anterior Asymmetry Index. The coefficient of degree 2 and order - 2 with a maximum degree of 4 is found to provide better results than the commonly computed anthropometric indexes in the detection of DP.This article was funded by Instituto de Salud Carlos III and European Regional Development Fund (FEDER) (Grant no. PI18/00881).Grieb, J.; Barbero-García, I.; Lerma, JL. (2022). Spherical harmonics to quantify cranial asymmetry in deformational plagiocephaly. Scientific Reports. 12(1):1-10. https://doi.org/10.1038/s41598-021-04181-z11012

    Contribution of 3D printing technology for craniofacial surgery

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    This article summarizes technical aspects of preparing printable 3D anatomical models created from radiological data (CT, MRI) and discusses their usefulness in surgery of the human skull. Interdisciplinary approach to the capabilities of the 3D printers, and the materials used for manufacturing 3D objects oriented on replicating anatomical structures has created new possibilities for simulating and planning surgical procedures in clinical practice settings
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