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Contact-free dynamical volumetric measurements of lower body with functional clinical and diagnostic capacity (AURORA)

Final Report Summary - AURORA (Contact-free dynamical volumetric measurements of lower body with functional clinical and diagnostic capacity)

The objective of the project AURORA was to develop a (relative) low cost diagnostic tool able to reconstruct and analyse movements and dynamics of the lower back and legs using anatomically correct models of the musculo-skeletal system. The system would carry out three dimensional surface measurements over time to provide a full volumetric analysis of movements and should meet the following requirements:
- non-invasive and no radiation;
- dynamic, full volume analysis;
- fast, automotive and easy to use;
- none or little preparation time.

The method is based on laser-generated stripe projection and reconstruction using triangulation. In a former EU project (4D BODYSCAN), it was shown that dynamic analysis of the human back is possible with a single one-sided white-light based system (this system is currently being world-wide distributed by Diers). For the AURORA project, however, a laser based system was selected due to the additional challenge of separating four different devices and due to the fact that we needed a bigger field of focused light (scan field).

Back and lower body musculo-skeletal problems are among the most frequent reasons for visits to the doctor and following work absence. Typically, X-rays or invasive methods are necessary to identify pathological changes, and it is rather difficult to objectively measure and quantify dynamic functional parameters of the lower body, as little equipment is developed for this purpose.

The technical objective was to develop a prototype system that is able to capture anatomical surface data of the human lower limb, within a cube of 1,2 x 1,2 x 1,2 m and with frequencies up to 30 Hz. Preferably, split laser beam technology (based on raster triangulation) will be used.

From the technical point of view major topic was the development of the optical hardware. R&G developed a one dimensional system for the projection of the laser lines. R&G has decided to use this technique because this seems to be the best solution to fulfil the demands in this project. Therefore, a split laser beam technology was developed which can project 120 horizontal stripes. The needed synchronisation unit to synchronise camera and laser was developed by Velomat and R&G.

The scientific objective was the development of musculo-skeletal models of the lower limb, based on body surface data, and integrating biomechanics knowledge from literature and own research. The models will allow diagnostic measurements of the leg axis, patella tracking, foot disorders and volume detection.

The existence of a diagnostic device as described here will permit that more people can be scanned and diagnosed and hence the awareness of the population of the importance of proper treatment of musculo-skeletal diseases will be raised.

To get data from real surface structures of the lower body the still existing four-dimensional (4D)-imager system was adopted to the legs. Even if the scan window is too small for the whole leg length, important data could be recorded. Based on the point clouds, generated by the DRACO software developed by DIERS, the partners responsible for image analysing and biomechanical modelling could work with this. Based on this WUT developed new algorithms for the point recognition. For validation of the real surface landmarks and the landmarks detected by the software skin markers were used. The automatic tracing during static and dynamic conditions is possible. The calculated xyz-coordinates finally can be used for the establishing of kinetic models developed by KUL. The needed anatomical reference points were defined by UKT.

Besides the detection of anatomical landmarks the processing and storage of the data was an important fact. For this purpose, WUT developed special software.

Especially in the field of clinical diagnosis the system offers a fast and non invasive diagnostic tool for the lower body. Especially, the non radiation technique will open a wide range of application. Compared to X-ray analysing the system should have the capacity for dynamic diagnosis. If the system can be produced to an acceptable price and the handling is easy than it is expected, that the consortium will have a good position to establish the system in the clinical world.

The status of the project was delayed for about six month due to the delay caused by problems in acquiring the cameras. It must be mentioned that the selection of the cameras was the most critical part of the project. Due to the not satisfying image quality the cameras needed to be changed twice. This resulted in a delay because adaptations in the acquisition and stripe detection software were needed. Even when after the last change only minor adaptations in the driver settings of the software were needed, this change caused additional changes in the following processes from acquisition, stripe detection, point cloud generation and full volume calculation. The delayed camera availability therefore resulted in an overall delay of the project working tasks. Some pre-work could be compensated by using the 4D-imager to get point clouds of the lower extremity. A first prototype with one camera and one synchronisation unit was constructed by R&G and Velomat and it was shown by them that it worked quite well as a single unit. It was clear that this project deals with a rather new technique and some risks must be taken into account.

The proposed technical task concerning the Hardware is fulfilled just in time. Also most of the software developments tasks were fulfilled. However, the clinical relevant tasks of evaluation and validation the system could not be completed. Real application of the system in a clinical surrounding could not be realised within the project time frame. UKT spent a lot of time in testing the system, with the result, that some corrections were needed. This lead to a further delay, thus no clinical measurements were possible.

To achieve a thorough evaluation of clinical, biomechanical and technical tasks, stable and reliable equipment is needed. The last measurements showed that with the new camera from PGR the system can fulfil this. The clinical evaluation and validation however could not be done and must be postponed to a following period.

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