Automatic modeling of an orthotic bracing for nonoperative correction of Pectus Carinatum

Pectus Carinatum is a deformity of the chest wall, characterized by an anterior protrusion of the sternum, often corrected surgically due to cosmetic motivation. This work presents an alternative approach to the current open surgery option, proposing a novel technique based on a personalized orthosis. Two different processes for the orthosis' personalization are presented. One based on a 3D laser scan of the patient chest, followed by the reconstruction of the thoracic wall mesh using a radial basis function, and a second one, based on a computer tomography scan followed by a neighbouring cells algorithm. The axial position where the orthosis is to be located is automatically calculated using a Ray-Triangle intersection method, whose outcome is input to a pseudo Kochenek interpolating spline method to define the orthosis curvature. Results show that no significant differences exist between the patient chest physiognomy and the curvature angle and size of the orthosis, allowing a better cosmetic outcome and less initial discomfort.The authors acknowledge to Foundation for Science and Technology (FCT) - Portugal for the fellowships with the references: SFRH/BD/74276/2010; SFRH/BD/68270/2010; UMINHO/BI/95/2012; and, SFRH/BPD/46851/2008. This work was also supported by FCT R&D project PTDC/SAUBEB/103368/2008

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