Biomedical subjects

S Däuber

Publications and source records attributed to S Däuber.

5 recordsLinked to original sources

PubMed2002

Analysing the variations of shapes based on surface-models.

In this paper we present a freely available application with which surface models, e.g. triangle meshes can be registered rigidly as well as by using similarity or affine transformations. Registered surfaces can be analysed, i.e. their difference can be calculated and visualised in various ways. The software is addressing the problem of evaluating shape differences of generated surface models due to mesh relaxation, decimation, object (in our case: patient) variation, different co-ordinate systems, etc. We invite all interested research personnel to download and use the software.

Artifacts↗

PubMed2002

[Processing medical image data for head surgery].

Three-dimensional models of the patient's anatomy are the basis for modern applications in computer-assisted surgery or radiology. To create these models the data is processed in a series of steps that transforms the initial raw data (generally CT/MRT volume images) into the three-dimensional models (e.g. triangle meshes). In doing so, a multitude of parameters adjustments, interactions and decisions are necessary to be made by the physician in order to create the models adapted to the specific needs of the patient and to the surgery. The quality of the models therefore strongly depends on that process chain. As a result of the high requirements on the quality and security of a clinical application the quality of the models itself and the capability to use them flexibly are essential. This work present a method to adjust and optimise the creation of the models and to asses their quality afterwards.

Artifacts↗

PubMed2001

Statistical analysis of the morphology of three-dimensional objects and pathologic structures using spherical harmonics.

To support diagnosis and therapy, it is a fundamental aim of medical image processing to describe morphological characteristics of pathological structures or image objects in general. Different authors propose quantitative methods of description like bounding boxes[1], fourier descriptors[2] or contour moments[3]. Unfortunately, these methods either don't supply a complete, respectively precise description of the object or only operate on two-dimensional images. Among the range of application are systems to classify lung nodules [4] or to help the diagnosis of brain tumors [5]. In this paper we present a method to analyze the morphology or shape of any three-dimensional object in order to describe it mathematically well-defined. We show how the description can be used to perform statistical operations on morphologies. The method presented in this paper was developed to assist the planning of craniofacial surgery. We analyze the shape of a given set of skull CT-data and use the mathematical description to statistically calculate the average shape of the skulls.

Cephalometry↗

PubMed2001

Intraoperative visualization of surgical planning data using video projectors.

The Institute for Process Control and Robotics has developed a new system using projector based augmented reality for the intraoperative visualization of preoperatively defined surgical planning data. Projector based augmented reality in medical applications represents a new field of research and gives an alternative solution to the commonly used Head Mounted Display technology. Moreover, the projector is not only used for visualization, but also for registration of the patient without the usage of invasive fiducial techniques as e.g. screw markers or frames. Recent results showed an achieved accuracy of +/- 1.5 mm which roughly meets clinical demands.

Data Display↗

PubMed2000

3D norm data: the first step towards semiautomatic virtual craniofacial surgery.

When planning craniofacial surgical interventions, the ideal appearance of the patient is very important. The final appearance should be as close as possible to that which the patient would have if he/she were without defects. Our first step towards achieving this is to build a database containing sets of three-dimensional CT images that allows for comparison of the shape of a patient with defects to the typical shape of an age- and sex-matched "average" person without defects. We started to collect CT data from patients without pathologies and, in co-operation with two radiology institutes (in Mannheim and Heidelberg), over 100 CT data sets have now been collected and classified according to age and sex. It is necessary to choose an appropriate statistical method to calculate the norm data from the different data sets. Based on the statistical method, an age- and sex-matched "average" model of the anatomy will be created.

Adolescent↗