Krzysztof Krysztoforski

Hardware approach to the artificial hand control algorithm realization

The concept of the bioprosthesis control system implementation in the dedicated hardware is presented. The complete control algorithm was analysed and the decomposition revealing the parts which could be calculated concurrently was made. Specialized digital circuits providing the wavelet transform and the neural network calculations were designed and successfully verified. The experiment results show that the proposed solution provides the desired dexterity and agility of the artificial hand.

Development of prototype for navigated real-time sonography for the head and neck region

To date, few imaging methods have been established for the head and neck region, in particular for soft tissues, that allow adequate visualization and simultaneously adequate real‐time orientation.

Noninvasive ultrasonic measuring system for bone geometry examination

Bone deformities are typically identified through standard radiograms. Since X‐ray examinations are easily applied and offer high quality imaging, noninvasive techniques are not commonly used in bone diagnostics. Nevertheless, nonradiological techniques are considered necessary because of the harmful effects of X‐ray radiation.

NAVIGATION-SUPPORTED AND SONOGRAPHICALLY-CONTROLLED FINE-NEEDLE PUNCTURE IN SOFT TISSUES OF THE NECK

In surgery, sonography has been a well-accepted means of orientation for years. The immediate vicinity of many vital structures in the head and neck region calls for a very exact visualization of the surgical instrument in the 2-D ultrasonic picture. We report on the development of a new method for navigation-supported and sonographically-controlled fine-needle puncture in soft tissues of the neck. Our system comprises a navigated ultrasound probe, a navigated fine-puncture needle and a coordinate sensor. A personal computer with specially-developed software assists calibration and surgical application. The applicability test for the system is described. In vitro, a model lymph node of 9 mm in diameter had been hit. It is shown that the target structure can be aimed at very precisely by the navigated puncture needle. An accuracy of 97% and a specificity of 99% could be demonstrated. The development of a very precise and easy-to-handle method for navigation-supported fine-needle puncture in the neck region is presented. The outstanding advantage of this method is that no rigid reference gadget fixed to the patients body is necessary. That makes this method very suitable for surgery in the neck region. Contrary to other sonographically-supported navigation methods in the head and neck region, preoperative imaging (CT or MRT) is dispensable.

Clinical factors affecting lower limb torsional deformities treatment with the Ilizarov method

INTRODUCTION One of the many uses of the Ilizarov fixator is for torsional deformities correction. Rotational and translational bone displacement related to torsional deformities correction includes the additional tension stresses, which affect the biology of the regenerated bone. Understanding the clinical factors will assist in designing the optimal treatment strategy, thus possibly improving the outcomes. PATIENTS AND METHODS It was case series retrospective study. The study examined 56 patients. The mean follow-up time was 5 years and 6 months. The mean age at the start of treatment was 19 years and 10 months. Patients underwent derotational corticotomies of distal metaphysis of the femur or proximal metaphysis of the tibia using the Ilizarov method. In these patients, following derotational corticotomies with the Ilizarov method, numerous variables were defined and their effect evaluated: the selected treatment strategy, the rate, size, type, and level of derotation on complications, the alignment index, the correction coefficient, the elongation index, and deformation correction factor. RESULTS The differences in the values of alignment index and deformation correction factor in this study subgroups were not statistically significant. We found differences in the elongation index and correction coefficient in a number of subgroups. DISCUSSION In the case of correcting torsional deformation without significant elongation, acute correction and with a value of >30° does not significantly affect the results. Treatment strategy, type and level of derotation had no major influence on torsional deformities treatment. LEVEL OF EVIDENCE Case-control study III.

Error analysis for determination of accuracy of an ultrasound navigation system for head and neck surgery.

Objective: The use of conventional CT- or MRI-based navigation systems for head and neck surgery is unsatisfactory due to tissue shift. Moreover, changes occurring during surgical procedures cannot be visualized. To overcome these drawbacks, we developed a novel ultrasound-guided navigation system for head and neck surgery. A comprehensive error analysis was undertaken to determine the accuracy of this new system. Materials and Methods: The evaluation of the system accuracy was essentially based on the method of error definition for well-established fiducial marker registration methods (point-pair matching) as used in, for example, CT- or MRI-based navigation. This method was modified in accordance with the specific requirements of ultrasound-guided navigation. The Fiducial Localization Error (FLE), Fiducial Registration Error (FRE) and Target Registration Error (TRE) were determined. Results: In our navigation system, the real error (the TRE actually measured) did not exceed a volume of 1.58 mm3 with a probability of 0.9. A mean value of 0.8 mm (standard deviation: 0.25 mm) was found for the FRE. The quality of the coordinate tracking system (Polaris localizer) could be defined with an FLE of 0.4 ± 0.11 mm (mean ± standard deviation). The quality of the coordinates of the crosshairs of the phantom was determined with a deviation of 0.5 mm (standard deviation: 0.07 mm). Conclusion: The results demonstrate that our newly developed ultrasound-guided navigation system shows only very small system deviations and therefore provides very accurate data for practical applications.

3D Bone Shape Modelling Basing on Dataset Recorded by Ultrasound Free-Hand Navigated Probe

The aim of this paper was to analyze the spatial geometry of objects basing on ultrasound images recorded by free-hand probe. The data analysis consists of three phases: data recording, contour segmentation and triangulation. Several algorithms of segmentation have been tested to recognize the object’s contour. To analyze the efficiency of triangulation algorithms, the similarities of obtained 3D models to the reference CT-based 3D model were evaluated. For objective and quantitative evaluation of obtained models the Hausdorff’s distances were calculated for compared surfaces. The results revealed higher efficiency of greedy projection method than the 2D Delaunay’s Triangulation applied for projected set of points in step by step procedure for the same cloud of points obtained as the result of user controlled segmentation procedure. The free hand ultrasonography can be applied to measure the spatial tissue shape for virtual planning of surgery without radiation.

Wavelet Processing Implementation in Digital Hardware

The paper describes an architecture and design of digital circuit dedicated for wavelet transform calculation, being a part of complex pattern recognition and control algorithm. The target application is artificial hand controlled by the nervous system of handicapped human, setting strict requirements on timing. Speed/size trade-off is discussed in general and in the context of this particular application. Floating point arithmetic was applied, based on the in-house developed solutions. The concept was implemented using VHDL, verified and successfully synthesized for FPGA programmable logic.

ARTIFICIAL HAND CONTROL PROBLEMS: HUMAN INTENTION RECOGNITION

Abstract The paper discusses the artificial hand movement control problem, treated as recognition of electromyography signals; it describes the measuring standard and the implementation aspects connected to EMG signals measurements. The methods used for reduction and classification of the EMG signals are presented together with the discussion of the factors affecting of movement decision recognition of human hand.