A Photogrammetric Technique for Acquiring Accurate Head Surfaces of Newborn Infants for Optical Tomography Under Clinical Conditions
Optical tomography (OT) generates 3D images that can be used to monitor blood volume and oxygenation in the brains of newborn infants safely and non‐invasively at the bedside. OT image reconstruction requires that source optical fibres and detector bundles (optodes) are brought into optical contact with the head and that the scalp surface geometry and optode positions for each individual infant are accurately known. The photogrammetric challenge is to create affordable tools that can be employed on newborn, and often severely ill, infants in an intensive care environment with a minimum level of intrusion. The paper describes the application and development of a system capable of mapping each individual infant head surface in the clinic and coordinating optode positions and orientations during optical tomography scans. The system developed includes a combination of stereo and multi‐photo photogrammetry with a pair of digital SLR cameras and a laser dot projector. A bundle adjustment of the sequential stereo‐image pairs is used to generate accurate head meshes that are combined with a photogrammetric network of images from a single camera to bring optodes mounted on a deformable helmet structure into a common coordinate system. This data can then be used in the 3D reconstruction of blood flow in the infant head.
Document Type: Research Article
Affiliations: ) University College London, UK
Publication date: 2012-09-01