Faulty postures, scoliosis and sagittal plane deformities should be detected as early as possible to apply preventive and treatment measures against major clinical consequences. To support documentation of the severity of deformity and diminish x-ray exposures, several solutions utilizing analysis of back surface topography data were introduced. A novel approach to automatic recognition and localization of anatomical landmarks of the human back is presented that may provide more repeatable results and speed up the whole procedure. The algorithm was designed as a two-step process involving a statistical model built upon expert knowledge and analysis of three-dimensional back surface shape data. Voronoi diagram is used to connect mean geometric relations, which provide a first approximation of the positions, with surface curvature distribution, which further guides the recognition process and gives final locations of landmarks. Positions obtained using the developed algorithms are validated with respect to accuracy of manual landmark indication by experts. Preliminary validation proved that the landmarks were localized correctly, with accuracy depending mostly on the characteristics of a given structure. It was concluded that recognition should mainly take into account the shape of the back surface, putting as little emphasis on the statistical approximation as possible.
The paper presents an optical three-dimensional shape measurement system and an automatic method for assessment of
pectus excavatum severity based on the measurement results. The measurement system consists of four directional
modules utilizing structured light projection method (namely temporal phase shifting TPS and modified Gray code
projection) to capture the shape of body surface of the patients. The measurement result is a three-dimensional point
cloud representing the skin surface. The system setup is described and the typical measurement parameters are given.
The automated data analysis path is explained. Its main stages are: point cloud segmentation, normalization of trunk
orientation, cutting the model into slices, analysis of each slice shape, selecting the proper slice for the assessment of
pectus excavatum of the patient and calculating its shape parameter. The analysis does not require any initial processing
(e.g. surface fitting or mesh building) as it is conducted on raw 3-D point cloud data resulting from the measurement. A
new shape parameter (I3ds) was developed that shows correlation with CT Haller Index widely used for assessment of
pectus excavatum. Preliminary clinical results are presented.
We present an automatic method for assessment of pectus excavatum severity based on an optical 3-D markerless shape measurement. A four-directional measurement system based on a structured light projection method is built to capture the shape of the body surface of the patients. The system setup is described and typical measurement parameters are given. The automated data analysis path is explained. Their main steps are: normalization of trunk model orientation, cutting the model into slices, analysis of each slice shape, selecting the proper slice for the assessment of pectus excavatum of the patient, and calculating its shape parameter. We develop a new shape parameter (I3ds) that shows high correlation with the computed tomography (CT) Haller index widely used for assessment of pectus excavatum. Clinical results and the evaluation of developed indexes are presented.
Bone tissue samples excised from the femoral heads of human were X-rayed together with the aluminum reference standard of density. The radiograms were scanned with the laser densitometer UltroScan XL (Pharmacia). Form the optical density profiles of bone samples the mean optical densities were determined. The optical densities were recalculated into equivalent thickness of the aluminium standard [mm Al]. Inter-measurement reproducibility of optical density determination was found to be very good (SD less than 3% of the mean). Relatively high variability (SD about 13% of the mean) was found for the optical density determination of a single bone sample X-rayed repeatedly. The inter-individual variability, which reflects the variability of bone tissue density between human subjects, was estimated as about 25% (SD as percent of the mean). We concluded that the laser densitometry performed according to our protocol provides the precise estimation of bone tissue density. Therefore, laser densitometry of bone tissue radiograms is potentially useful method for studies of bone in medical research and diagnosis.
Irradiation of the hyaline or fibrous cartilage excised from the body of a human cadaver with Er:YAG laser beam, single pulse with a dose of 1 J, produces a crater with a depth of approximately 500 micrometers and a diameter varying from 5 to 300 micrometers. Histological examination has revealed that the laser-made craters were surrounded by a thin rim (2-10 micrometer) of charred and coagulated tissue. No damage was observed in the cartilage surrounding the rim. The presence of sharp demarcation between the tissue areas ablated by laser energy and the undamaged areas argues for the potential usefulness of the Er:YAG laser in surgery of cartilages.