Krzysztof Murawski

Improvement of accuracy of the membrane shape mapping of the artificial ventricle by eliminating optical distortion

The paper presents new technique for correcting the desired shape of the flaccid membrane used in the artificial heart chamber. The original shape of membrane was obtained using specially developed type of method — Depth from Defocus. Accurately determining the shape of the diaphragm is very important. The shape of the membrane affects the final accuracy of determining the stroke volume of extracorporeal pneumatic heart assist pump. Three rigid membranes were used in the study. Each of them was developed on the basis of the original shape of the flaccid membrane and was examined.

Research to improve the accuracy of determining the stroke volume of an artificial ventricle using the wavelet transform

In the article we presented results obtained during research, which are the continuation of work on the use of artificial neural networks to determine the relationship between the view of the membrane and the stroke volume of the blood chamber of the mechanical prosthetic heart. The purpose of the research was to increase the accuracy of determining the blood chamber volume. Therefore, the study was focused on the technique of the features that the image extraction gives. During research we used the wavelet transform. The achieved results were compared to the results obtained by other previous methods. Tests were conducted on the same mechanical prosthetic heart model used in previous experiments.

Determining the stroke volume of the artificial ventricle using the numerical integration method

This paper sets out and presents a new approach to determine the stroke volume of the artificial ventricle. The stroke volume of the chamber is one of the basic heart function parameters. For the artificial heart assist purpose, in the study this value is calculated based on the mapped shape of the flaccid membrane of the extracorporeal pneumatic heart assist pump. This is a continuation of the earlier work on the use of image processing and analysis techniques to determine the membrane shape and the stroke volume of an artificial ventricle. The study focused on the determining the stroke volume using the numerical integration method. To do this, the membrane shape in the actual dimensions in millimetres is first mapped, and then a double integral under this surface is calculated. The comparison of different ways of numerical integration for different sizes of the measurement matrix as well as the obtained results were presented.

The membrane shape mapping of the artificial ventricle in the actual dimensions

The paper sets out and presents a new approach to determine the shape of the flaccid membrane of the extracorporeal pneumatic heart assist pump. This is a continuation of earlier work on the use of image processing and analysis techniques to determine the membrane shape of an artificial ventricle. The study focused on the membrane shape mapping in the actual dimensions — in the real world. The method to transform measurement results in pixels to dimensions in the real world in millimetres as well as the obtained results of this process were presented.

The technique of accuracy measurement of membrane shape mapping of an artificial ventricle

In the paper the research results, which are a continuation of work on the use of image processing techniques to determine the membrane shape of an artificial ventricle, were presented. The studies focused on developing a technique for measuring the accuracy of the membrane shape mapping. It is important to ensure the required accuracy of determining the instantaneous stroke volume of a controlled pneumatic artificial ventricular. Experiments were carried out on the following type of membrane models: convex, flat and concave. The purpose of the research was to obtain a numerical indicator, which will be used to evaluate the options to improve mapping techniques of thee shape of the membrane.

Studying the influence of object size on the range of distance measurement in the new Depth From Defocus method

The article presents new results achieved during researching the distance measuring method that is a part of Depth From Defocus techniques. The method has been developed to determine the shape of the flaccid diaphragm used in the Ventricular Assist Device (VAD). The shape is determined on the basis of distance measured between the CCD sensor plate of the camera and objects (markers) located on the flaccid diaphragm. Experiments were carried out using a stationary camera and circular markers with a diameter from 3 mm to 9 mm. The goal of this paper is to present the influence of the object (marker) size on the distance range measured between the camera and diaphragm used in the external pneumatic prosthetic heart.

Measuring the stroke volume of the pneumatic heart prosthesis using an artificial neural network

The paper presents the use of an artificial neural network in sensors application. The task is to determine the volume of the chamber. The tests were performed on a model of a chamber in a mechanical prosthetic heart. In the considered task the surface of the diaphragm is observed by a near-infrared band camera. The artificial neural network was used to determine the relationship between the real views of the diaphragm and stroke volume. The artificial neural network learning process and research results are presented in the article.

A new innovative depth From defocus method - identification of the impact of the marker size on the distance measurement result

The article presents results achieved during researching the distance measuring method belonging to Depth From Defocus techniques. The method has been developed to determining the shape of the flaccid membrane used in the Ventricular Assist Device (VAD). The shape is determined on the basis of distance measured between the CCD sensor plate of the camera and objects (markers) located on the flaccid membrane. The experiments were carried out using a stationary camera and circular markers with a diameter from 0,003m to 0,009 m. The goal of this paper is to present the influence of the size of the object (marker) on the distance range measured between the camera and diaphragm used in the pneumatic prosthetic heart.

Visual measurement of any shape of the flaccid membrane of the extracorporeal pneumatic heart assist pump

The new visual method has been invented in order to measure the stroke volume of the extracorporeal pneumatic heart assist pump. Heart pumps of this type have a pneumatic chamber and a blood chamber separated by a flaccid membrane. Equipping the heart pump with a miniature camera makes it possible to observe the surface of the membrane from the pneumatic chamber side without obstructing its normal operation. The momentary shape of the flaccid membrane affects the volume of the blood chamber. The essence of the used measurement method is to observe a surface of the membrane using a camera and to determine the shape of this membrane in the actual 3-dimensional space, only on the basis of a one-shot image. This method works due to markers arranged on the surface of the membrane from the pneumatic chamber side. In the measurement, the image processing and analysis techniques are used. The difficulty of the accuracy verification of the shape mapping is that heart assist pump fitted with a flaccid membrane has only two membrane states with a known mathematical description. Research has already been conducted to verify the method for the extreme states and it has produced very good results. Invented new technique to 3D modeling of any shape of the flaccid membrane with well-known geometric dimensions allowed verifying the method for any shape of the membrane. The real membrane was replaced in sequence with four different rigid models with the known geometric dimensions. Results obtained in the study were presented.

Application of 3D printed models to visual measurement in the new innovative depth from defocus method

The new innovative Depth from Defocus (DFD) method was used to visual measurement of the stroke volume of the extracorporeal pneumatic heart assist pump. The heart pump developed in the framework of the Polish Artificial Heart is the object of the study. However, the current studies are conducted on its adequate model. Using this model is justified because of the significant costs of the original prosthesis. The model was equipped with an adapter to mount the camera. This makes it possible to observe the surface of the membrane from the pneumatic chamber side without obstructing its normal operation, in particular without affecting the blood chamber. The model was designed in CAD software then it was 3D printed. The momentary surface shape of the flaccid membrane affects the volume of the blood chamber. The difficulty of the accuracy verification of the shape mapping is that heart assist pump fitted with a flaccid membrane has only two membrane states with a known mathematical description. Using reverse engineering, the authors have invented new technique to 3D modeling of any surface shape of the flaccid membrane with well-known geometric dimensions. The rigid models of different membrane states were designed in CAD software and printed on a 3D printer. The process of modeling and 3D printing and ready prototypes were presented.