44 research outputs found
A comparative study of breast surface reconstruction for aesthetic outcome assessment
Breast cancer is the most prevalent cancer type in women, and while its
survival rate is generally high the aesthetic outcome is an increasingly
important factor when evaluating different treatment alternatives. 3D scanning
and reconstruction techniques offer a flexible tool for building detailed and
accurate 3D breast models that can be used both pre-operatively for surgical
planning and post-operatively for aesthetic evaluation. This paper aims at
comparing the accuracy of low-cost 3D scanning technologies with the
significantly more expensive state-of-the-art 3D commercial scanners in the
context of breast 3D reconstruction. We present results from 28 synthetic and
clinical RGBD sequences, including 12 unique patients and an anthropomorphic
phantom demonstrating the applicability of low-cost RGBD sensors to real
clinical cases. Body deformation and homogeneous skin texture pose challenges
to the studied reconstruction systems. Although these should be addressed
appropriately if higher model quality is warranted, we observe that low-cost
sensors are able to obtain valuable reconstructions comparable to the
state-of-the-art within an error margin of 3 mm.Comment: This paper has been accepted to MICCAI201
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
The VHP-F Computational Phantom and its Applications for Electromagnetic Simulations
Modeling of the electromagnetic, structural, thermal, or acoustic response of the human body to various external and internal stimuli is limited by the availability of anatomically accurate and numerically efficient computational models. The models currently approved for use are generally of proprietary or fixed format, preventing new model construction or customization. 1. This dissertation develops a new Visible Human Project - Female (VHP-F) computational phantom, constructed via segmentation of anatomical cryosection images taken in the axial plane of the human body. Its unique property is superior resolution on human head. In its current form, the VHP-F model contains 33 separate objects describing a variety of human tissues within the head and torso. Each obejct is a non-intersecting 2-manifold model composed of contiguous surface triangular elements making the VHP-F model compatible with major commercial and academic numerical simulators employing the Finite Element Method (FEM), Boundary Element Method (BEM), Finite Volume Method (FVM), and Finite-Difference Time-Domain (FDTD) Method. 2. This dissertation develops a new workflow used to construct the VHP-F model that may be utilized to build accessible custom models from any medical image data source. The workflow is customizable and flexible, enabling the creation of standard and parametrically varying models facilitating research on impacts associated with fluctuation of body characteristics (for example, skin thickness) and dynamic processes such as fluid pulsation. 3. This dissertation identifies, enables, and quantifies three new specific computational bioelectromagnetic problems, each of which is solved with the help of the developed VHP-F model: I. Transcranial Direct Current Stimulation (tDCS) of human brain motor cortex with extracephalic versus cephalic electrodes; II. RF channel characterization within cerebral cortex with novel small on-body directional antennas; III. Body Area Network (BAN) characterization and RF localization within the human body using the FDTD method and small antenna models with coincident phase centers. Each of those problems has been (or will be) the subject of a separate dedicated MS thesis
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
Predicting Breast Healing Deformation After Cancer Conservative Treatment
De acordo com a Organização Mundial de Saúde, o cancro da mama é o cancro mais frequente entre indivÃduos do sexo feminino. Tendo em conta todos os tratamentos actualmente disponÃveis, a cirurgia é aplicada maioritariamente usando duas metodologias: Mastectomia, que resulta na remoção total da mama e não apenas do tumor; e Tratamento Conservativo do Cancro da Mama no qual apenas é removido o tumor e uma porção reduzida do tecido da mama circundante. Como esperado, a aplicação de tratamento invasivos como o caso da cirurgia leva à deformação da mama afectando a qualidade de vida dos pacientes. Desta forma, a tecnologia poderá ser utilizada de modo a melhorar a interacção entre os pacientes e médicos clÃnicos de modo a visualizar as possÃveis deformações resultantes e o processo de cicatrização após a cirurgia com o intuito de melhorar a qualidade de vida dos pacientes.De modo a atingir o objectivo acima descrito, é necessário obter modelos de treino capazes de descrever deformações anatómicas ao longo do processo de cicatrização da mama após Tratamento Conservativo do Cancro da Mama. Para que se obtenham modelos de treino viáveis é necessário um dataset com vários modelos 3D. Assim sendo, terá de ser gerado um dataset semi-sintético com modelos 3D representando as mamas das pacientes antes e após a cirurgia. Os modelos pré-cirurgicos serão obtidos com base em informação proveniente de ressonâncias magnéticas das pacientes à s quais temos acesso. A informação semi-sintética pré-cirurgica terá em conta a informação real e variações das localizações e volume hipotéticos do tumor e da possÃvel densidade da mama. Os modelos pós-cirurgicos serão simulados com base num modelo biomecânico de cicatrizaçãoPosteriormente, através da utilização de técnicas de aprendizagem computacional, poder-se-á então obter uma relação entre os modelos da mama da paciente antes e após a cirurgia.Por último, de modo a validar os modelos de previsão, os modelos simulados serão comparados o modelo pós-cirurgico previsto usando diversas métricas como distâncias Euclidianas e de Hausdorff.According to the annual report from the World Health Organization, breast cancer is the most frequent cancer among females. Considering all the treatments, surgery is being applied mostly using two methodologies: Mastectomy, that results on removing not only tumor, but also the total breast tissue; and Breast Cancer Conservative Treatment (BCCT) where only the tumor is removed with a thin layer of healthy tissue around it. It is clear that performing invasive treatment such as surgery, will lead to impose deformations on the breast, which can influence patients' quality of life (QoL). In this way, technology can be assisted to provide a framework that would improve the way patients interact with physicians. Enhancing this framework with the tools to visualize deformation and the healing process after the surgery can elevate patients' QoL.In order to accomplish the mentioned aim, this thesis focuses on obtaining training models to describe anatomical deformations during the healing process of the breast after BCCT. To achieve reliable training models, a dataset with several 3D breast models is required. Therefore, a semi-synthetic dataset may be generated, containing 3D breast models representing the patients' breasts before and after the surgery. The pre-surgical models are obtained through MRI data of the few patients' data that we have access. The semi-synthetic data of the pre-surgical stage will be generated taking as input these real data and variations of the hypothetic tumor's location and volume and possible breast densities. The pos-surgical data is simulated by a biomechanical wound healing model. Then by using different machine learning approaches, the relation between the patient's breast before and after the surgery can be obtained and the deformation predicted.Finally, concerning the evaluation, simulated healed breasts will be compared with the pos-surgical 3D breast models in the dataset through several metrics including Euclidean and Hausdorff distances
Computerized Analysis of Magnetic Resonance Images to Study Cerebral Anatomy in Developing Neonates
The study of cerebral anatomy in developing neonates is of great importance for
the understanding of brain development during the early period of life. This
dissertation therefore focuses on three challenges in the modelling of cerebral
anatomy in neonates during brain development. The methods that have been
developed all use Magnetic Resonance Images (MRI) as source data.
To facilitate study of vascular development in the neonatal period, a set of image
analysis algorithms are developed to automatically extract and model cerebral
vessel trees. The whole process consists of cerebral vessel tracking from
automatically placed seed points, vessel tree generation, and vasculature
registration and matching. These algorithms have been tested on clinical Time-of-
Flight (TOF) MR angiographic datasets.
To facilitate study of the neonatal cortex a complete cerebral cortex segmentation
and reconstruction pipeline has been developed. Segmentation of the neonatal
cortex is not effectively done by existing algorithms designed for the adult brain
because the contrast between grey and white matter is reversed. This causes pixels
containing tissue mixtures to be incorrectly labelled by conventional methods. The
neonatal cortical segmentation method that has been developed is based on a novel
expectation-maximization (EM) method with explicit correction for mislabelled
partial volume voxels. Based on the resulting cortical segmentation, an implicit
surface evolution technique is adopted for the reconstruction of the cortex in
neonates. The performance of the method is investigated by performing a detailed
landmark study.
To facilitate study of cortical development, a cortical surface registration algorithm
for aligning the cortical surface is developed. The method first inflates extracted
cortical surfaces and then performs a non-rigid surface registration using free-form
deformations (FFDs) to remove residual alignment. Validation experiments using
data labelled by an expert observer demonstrate that the method can capture local
changes and follow the growth of specific sulcus
Robust signatures for 3D face registration and recognition
PhDBiometric authentication through face recognition has been an active area of
research for the last few decades, motivated by its application-driven demand. The popularity
of face recognition, compared to other biometric methods, is largely due to its
minimum requirement of subject co-operation, relative ease of data capture and similarity
to the natural way humans distinguish each other.
3D face recognition has recently received particular interest since three-dimensional
face scans eliminate or reduce important limitations of 2D face images, such as illumination
changes and pose variations. In fact, three-dimensional face scans are usually captured
by scanners through the use of a constant structured-light source, making them invariant
to environmental changes in illumination. Moreover, a single 3D scan also captures the
entire face structure and allows for accurate pose normalisation.
However, one of the biggest challenges that still remain in three-dimensional face
scans is the sensitivity to large local deformations due to, for example, facial expressions.
Due to the nature of the data, deformations bring about large changes in the 3D geometry
of the scan. In addition to this, 3D scans are also characterised by noise and artefacts such
as spikes and holes, which are uncommon with 2D images and requires a pre-processing
stage that is speci c to the scanner used to capture the data.
The aim of this thesis is to devise a face signature that is compact in size and
overcomes the above mentioned limitations. We investigate the use of facial regions and
landmarks towards a robust and compact face signature, and we study, implement and
validate a region-based and a landmark-based face signature. Combinations of regions and
landmarks are evaluated for their robustness to pose and expressions, while the matching
scheme is evaluated for its robustness to noise and data artefacts
Development of Human Body CAD Models and Related Mesh Processing Algorithms with Applications in Bioelectromagnetics
Simulation of the electromagnetic response of the human body relies heavily upon efficient computational CAD models or phantoms. The Visible Human Project (VHP)-Female v. 3.1 - a new platform-independent full-body electromagnetic computational model is revealed. This is a part of a significant international initiative to develop powerful computational models representing the human body. This model’s unique feature is full compatibility both with MATLAB and specialized FEM computational software packages such as ANSYS HFSS/Maxwell 3D and CST MWS. Various mesh processing algorithms such as automatic intersection resolver, Boolean operation on meshes, etc. used for the development of the Visible Human Project (VHP)-Female are presented. The VHP - Female CAD Model is applied to two specific low frequency applications: Transcranial Magnetic Stimulation (TMS) and Transcranial Direct Current Stimulation (tDCS). TMS and tDCS are increasingly used as diagnostic and therapeutic tools for numerous neuropsychiatric disorders. The development of a CAD model based on an existing voxel model of a Japanese pregnant woman is also presented. TMS for treatment of depression is an appealing alternative to drugs which are teratogenic for pregnant women. This CAD model was used to study fetal wellbeing during induced peak currents by TMS in two possible scenarios: (i) pregnant woman as a patient; and (ii) pregnant woman as an operator. An insight into future work and potential areas of research such as a deformable phantom, implants, and RF applications will be presented