Modified mass-spring system for physically based deformation modeling

Mass-spring systems are considered the simplest and most intuitive of all deformable models. They are computationally efficient, and can handle large deformations with ease. But they suffer several intrinsic limitations. In this book a modified mass-spring system for physically based deformation modeling that addresses the limitations and solves them elegantly is presented. Several implementations in modeling breast mechanics, heart mechanics and for elastic images registration are presented

Modified mass-spring system for physically based deformation modeling

Mass-spring systems are considered the simplest and most intuitive of all deformable models. They are computationally efficient, and can handle large deformations with ease. But they suffer several intrinsic limitations. In this book a modified mass-spring system for physically based deformation modeling that addresses the limitations and solves them elegantly is presented. Several implementations in modeling breast mechanics, heart mechanics and for elastic images registration are presented

Nonrigid reconstruction of 3D breast surfaces with a low-cost RGBD camera for surgical planning and aesthetic evaluation

Accounting for 26% of all new cancer cases worldwide, breast cancer remains the most common form of cancer in women. Although early breast cancer has a favourable long-term prognosis, roughly a third of patients suffer from a suboptimal aesthetic outcome despite breast conserving cancer treatment. Clinical-quality 3D modelling of the breast surface therefore assumes an increasingly important role in advancing treatment planning, prediction and evaluation of breast cosmesis. Yet, existing 3D torso scanners are expensive and either infrastructure-heavy or subject to motion artefacts. In this paper we employ a single consumer-grade RGBD camera with an ICP-based registration approach to jointly align all points from a sequence of depth images non-rigidly. Subtle body deformation due to postural sway and respiration is successfully mitigated leading to a higher geometric accuracy through regularised locally affine transformations. We present results from 6 clinical cases where our method compares well with the gold standard and outperforms a previous approach. We show that our method produces better reconstructions qualitatively by visual assessment and quantitatively by consistently obtaining lower landmark error scores and yielding more accurate breast volume estimates

A rigid 3D registration framework of women body RGB-D images

O trabalho realizado foca-se no melhoramento e automatização da framework desenvolvida para o projeto PICTURE do grupo de investigação VCMI do INESC-TEC. O principal objetivo tem que ver com a criação de modelos 3D do torso de pacientes com cancro da mama, a partir de dados adquiridos com sensores RGB-D low-cost, como o Kinect da Microsoft. As contribuições da tese passam pela criação de algoritmos para a automatização de processos, tais como: seleção da pose da mulher, segmentação do torso, remoção de ruído e o registo de múltiplas nuvens de pontos. O trabalho tem decorrido de forma aproximada o plano traçado no relatório de PDI, e neste momento encontra-se numa fase de finalização da implementação e testes para validação dos algoritmos desenvolvidos. Por outro lado, já foi iniciado o processo de escrita do documento final da Dissertação

Development and Validation of a Three-Dimensional Optical Imaging System for Chest Wall Deformity Measurement

Congenital chest wall deformities (CWD) are malformations of the thoracic cage that become more pronounced during early adolescence. Pectus excavatum (PE) is the most common CWD, characterized by an inward depression of the sternum and adjacent costal cartilage. A cross-sectional computed tomography (CT) image is mainly used to calculate the chest thoracic indices. Physicians use the indices to quantify PE deformity, prescribe surgical or non-surgical therapies, and evaluate treatment outcomes. However, the use of CT is increasingly causing physicians to be concerned about the radiation doses administered to young patients. Furthermore, radiographic indices are an unsafe and expensive method of evaluating non-surgical treatments involving gradual chest wall changes. Flexible tape or a dowel-shaped ruler can be used to measure changes on the anterior side of the thorax; however, these methods are subjective, prone to human error, and cannot accurately measure small changes. This study aims to fill this gap by exploring three-dimensional optical imaging techniques to capture patients’ chest surfaces. The dissertation describes the development and validation of a cost-effective and safe method for objectively evaluating treatment progress in children with chest deformities. First, a study was conducted to evaluate the performance of low-cost 3D scanning technologies in measuring the severity of CWD. Second, a multitemporal surface mesh registration pipeline was developed for aligning 3D torso scans taken at different clinical appointments. Surface deviations were assessed between closely aligned scans. Optical indices were calculated without exposing patients to ionizing radiation, and changes in chest shape were visualized on a color-coded heat map. Additionally, a statistical model of chest shape built from healthy subjects was proposed to assess progress toward normal chest and aesthetic outcomes. The system was validated with 3D and CT datasets from a multi-institutional cohort. The findings indicate that optical scans can detect differences on a millimeter scale, and optical indices can be applied to approximate radiographic indices. In addition to improving patient awareness, visual representations of changes during nonsurgical treatment can enhance patient compliance

Breast Modeling Towards an Educational Tool for Breast Cancer Surgeons

Deformações da mama que ocorram devido a possíveis complicações ou procedimentos da cirurgia de remoção de cancro da mama, podem ter impacto na aparência física e afectar negativamente o estado psicológico da pessoa em causa. Estes impactos psicológicos são mais frequentes nas mulheres, visto que as mamas são socialmente vista como um ícone de feminidade e fertilidade. Quando diagnosticadas com cancro da mama, os tratamentos mais frequentes a que as doentes são sujeitas são radioterapia, quimioterapia e cirurgia. Dentro das cirurgias, a mastectomia é a que mais mulheres temem dado ser a mais radical e bastante invasiva pelo facto de ser removido todo o tecido que constitui a mama. Não obstante, hoje em dia já existem alternativas menos radicais como o tratamento conservador do cancro da mama, que é menos invasiva, pois só remove o tumor e algum tecidos circundante. As técnicas mais recentes como Breast Conserving Surgery têm como objectivo maior eficácia e a obtenção de um melhor resultado estético. Embora exista práticas de trabalho muito heterogéneas que levem a resultados estéticos diferentes. Criar uma ferramenta educacional de treino para os novos cirurgiões para BCS revela-se bastante útil para cirurgiões recém-formados. Pois a ferramenta ajudara-os a tornarem-se melhores profissionais antes de terem experiência, já que existe uma relação entre experiência e resultado estético de uma cirurgia. Estudos mostram que o resultado de uma cirurgia pode ser influenciado pela experiência do cirurgião ou seja, quanta mais experiência (número de cirurgias praticadas) este tiver, melhores serão os resultados obtidos. Para poder criar uma ferramenta de treino foram usados modelos paramétricos 3D e sintéticos para simular a superfície da mama (com ou sem deformações), o seu interior e outras estruturas como tórax e o músculo do peitoral.O utilizador tem de introduzir certos dados como: volume, tipo de mama e projecção da mesma. A densidade mámaria é representada pelos quatro tipos em classificação Breast Imaging-Reporting and Data System (BI-RADS). Para representar o tumor no modelo é essencial: o quadrante de onde se encontra na mama, estágio de desenvolvimento e a sua forma, redondo ou especulado.A ferramenta educativa, disponibiliza de uma interface, previamente testada e validada pela sua usabilidade e eficácia por varias propostas de interface.Breast deformities that occur due to possible complications or procedures of breast cancer removal surgery can have an impact on its physical appearance and adversely affect the psychological state of the person concerned. This psychological impacts happens particularly in women, since the breast is socially seen as an icon of femininity and fertility.When diagnosed with breast cancer, the most frequent treatments are radiation therapy, chemotherapy, and surgery.Within the surgeries, mastectomy is the one that most women fear since the intervention is more radical and quite invasive due to the fact that all the breast tissues are removed. Nonetheless, there are less radical alternatives such as the conservative treatment of breast cancer, which is less invasive and preserves more the breast aesthetics because it only removes the tumor and some surrounding tissues. The latest techniques such as Breast Conserving Surgery (BCS) aims to achieve greater efficiency and a better aesthetic result. Although there are very heterogeneous practices that lead to different aesthetic results.Creating an educational training framework for conservative surgery may be very useful for newly trained surgeons. The framework will help them become better professionals before obtaining experience, since there is a relationship between experience and the outcome of a surgery. Studies show that the result of a surgery can be influenced by the experience of the surgeons, ie, the more experience (number of surgeries performed) the surgeon has, better are the results obtained.In order to create a training framework, parametric and synthetic 3D models were used to simulate the surface of the breast (with or without deformities), its interior and other structures such as thorax and pectoral muscle.The inputs required to simulate the breast surface are volume, breast type and its projection. The breast density is represented by 4 types of Breast Imaging-Reporting and Data System (BI-RADS) classification. To represent the tumor in the model it is essential to know the quadrant in the breast, its stage of development and the tumor form, round or speculated.The educational tool has an interface, previously tested and validated for its usability and effectiveness between several interface prototypes

Anatomical curve identification

Methods for capturing images in three dimensions are now widely available, with stereo-photogrammetry and laser scanning being two common approaches. In anatomical studies, a number of landmarks are usually identified manually from each of these images and these form the basis of subsequent statistical analysis. However, landmarks express only a very small proportion of the information available from the images. Anatomically defined curves have the advantage of providing a much richer expression of shape. This is explored in the context of identifying the boundary of breasts from an image of the female torso and the boundary of the lips from a facial image. The curves of interest are characterised by ridges or valleys. Key issues in estimation are the ability to navigate across the anatomical surface in three-dimensions, the ability to recognise the relevant boundary and the need to assess the evidence for the presence of the surface feature of interest. The first issue is addressed by the use of principal curves, as an extension of principal components, the second by suitable assessment of curvature and the third by change-point detection. P-spline smoothing is used as an integral part of the methods but adaptations are made to the specific anatomical features of interest. After estimation of the boundary curves, the intermediate surfaces of the anatomical feature of interest can be characterised by surface interpolation. This allows shape variation to be explored using standard methods such as principal components. These tools are applied to a collection of images of women where one breast has been reconstructed after mastectomy and where interest lies in shape differences between the reconstructed and unreconstructed breasts. They are also applied to a collection of lip images where possible differences in shape between males and females are of interest

Development and Validation Methodology of the Nuss Procedure Surgical Planner

Pectus excavatum (PE) is a congenital chest wall deformity which is characterized, in most cases, by a deep depression of the sternum. A minimally invasive technique for the repair of PE (MIRPE), often referred to as the Nuss procedure, has been proven to be more advantageous than many other PE treatment techniques. The Nuss procedure consists of placement of a metal bar(s) underneath the sternum, thereby forcibly changing the geometry of the ribcage. Because of the prevalence of PE and the popularity of the Nuss procedure, the demand to perform this surgery is greater than ever. Therefore, a Nuss procedure surgical planner would be an invaluable planning tool ensuring an optimal physiological and aesthetic outcome. In this dissertation, the development and validation of the Nuss procedure planner is investigated. First, a generic model of the ribcage is developed to overcome the issue of missing cartilage when PE ribcages are segmented and facilitate the flexibility of the model to accommodate a range of deformity. Then, the CT data collected from actual patients with PE is used to create a set of patient specific finite element models. Based on finite element analyses performed over those models, a set force-displacement data set is created. This data is used to train an artificial neural network to generalize the data set. In order to evaluate the planning process, a methodology which uses an average shape of the chest for comparison with results of the Nuss procedure planner is developed. This method is based on a sample of normal chests obtained from the ODU male population using laser surface scanning and overcomes challenging issues such as hole-filling, scan registration and consistency. Additionally, this planning simulator is optimized so that it can be used for training purposes. Haptic feedback and inertial tracking is implemented, and the force-displacement model is approximated using a neural network approach and evaluated for real-time performance. The results show that it is possible to utilize this approximation of the force-displacement model for the Nuss procedure simulator. The detailed ribcage model achieves real-time performance