A 4D-Optical Measuring System for the Dynamic Acquisition of Anatomical Structures Kathleen Denis 1 , Tom Huysmans 1 , Tom De Wilde 1 , Cristian Forausberger 1 , Walter Rapp 1 , Bart Haex 1 , Jos Vander Sloten 1 , Remi Van Audekercke 1 , Georges Van der Perre 1 , Kjell Roger Heitmann 2 , and Helmut Diers 2 1 Division of Biomechanics and Engineering Design, K.U.Leuven, Celestijnenlaan 200A, B-3001 Leuven, Belgium 2 Diers International GmbH, Dillenbergweg 4, 65388 Schlangenbad, Germany Abstract. This paper presents a novel measuring system for the detec- tion of moving skeletal structures. The system uses white light raster line triangulation in combination with biomechanical modeling techniques. White light raster line triangulation visualizes surfaces (e.g. the back surface) in an accurate and repeatable way, without detrimental effects, and without making contact to the human body. By making use of mod- eling techniques such as active contour models, active shape models and inverse kinematic models, biomechanically relevant results such as the position of the skeletal segments during motion are obtained. 1 Introduction 1.1 Clinical Relevance The number of people suffering from musculoskeletal complaints, such as low back pain, is huge. It is by far the most important cause for work absenteeism in Europe, and as the population is increasingly sedentary and ageing, it is a growing problem. Orthopedic physicians and physiotherapists are required to analyze a variety of movements to diagnose pathological or abnormal changes. Therefore, an objective measurement tool to provide the medical examiner or the physiotherapist with clinically relevant data to support the diagnosis and therapy plan is required. 1.2 Innovation of the Measuring System Standard diagnosis methods for musculoskeletal problems consist of expensive medical procedures (e.g. CT scans), involving potentially harmful ionizing radi- ation, or require expert operator interaction (e.g. 3D motion analysis based on marker tracing). Most of these methods are aimed at static purposes only and do therefore not involve dynamic measurements. Furthermore they show problems in specific cases (e.g. shift of markers on skin in marker tracing systems). So far, low cost measurement devices for preventive screening, diagnosis or treatment C. Barillot, D.R. Haynor, and P. Hellier (Eds.): MICCAI 2004, LNCS 3217, pp. 259–266, 2004. c  Springer-Verlag Berlin Heidelberg 2004