Endothelial Evaluation of Corneal Transplants by Knowledge-Based Digital Image Processing

Author(s):
Georg Toszkowski - FH Niederrhein, University of Applied Sciences
Norbert Dahmen - FH Niederrhein, University of Applied Sciences

Industry:
Life Science

Products:
Vision, LabVIEW

The Challenge:
Automating the endothelial cell density analysis of human corneal transplants for successful keratoplastics.

The Solution:
Development of a facilitated and reliable diagnostic tool for endothelial cell density evaluation using a knowledge-based digital image processing approach.

Introduction
With the ever-decreasing prices of computer hardware and software, using machine vision products becomes more and more attractive in the measurement and automation industry. Lower prices, however, are not the only reason for a higher acceptance of such products. Another cause of this development is the ever-growing time efficiency of the software tools available for such applications.

To ensure shorter development cycles, developers are using software tools for analysis and rapid prototyping, as well as development environments with libraries containing special vision functions. The functions of the analysis tool and the development environment often do not correspond to one another, causing a communication problem. Mostly, the analysis tool does not include the same functions as the development environment, so we must create relevant functions in a very elaborate way.

With the introduction of IMAQ Vision Builder, National Instruments provides developers with a product bridging the gap between the rapid-prototyping tool and the development environment. When using LabVIEW, the function library of Advanced IMAQ Vision has proven a perfect solution for developing industrial vision applications. Because the principle of data flow is the basis of graphical programming, the results are parallel ways of programming and documenting, causing a reduction in development time and innovation cycles.

IMAQ Vision Builder
With the browser of the IMAQ Vision Builder, the handling of the program is very easy. We can load acquired data (images); however, thanks to the fact that the browser handles all hardware products of the IMAQ series, we can also directly acquire images by camera or video and display and select them in a list.
After we have selected the corresponding images, we can process them with the help of all available functions in regard to identification, parameterization, and implementation.

We enter every operational step into a script. This script, however, is more than a simple log. We can change, replace, or even delete parameters of operations that have already taken place. As a result, we can then immediately view the whole sequence of steps.

Nevertheless, we can do more than simply save and reload scripts developed in this way. We can also use them to generate a Builder File - a text file that provides the developer with exact instructions to realize the corresponding processing steps with the help of Advanced IMAQ Vision. In addition, the scripts contain the exact order of the identifiers and parameters of the required virtual instruments.

A Vision Application
An example of developing a vision application with the help of IMAQ Vision Builder is the following solution built in cooperation between the LIONS Cornea Bank of the Eye Hospital and the Laboratory for Microprocessor Technology of the University of Applied Sciences Niederrhein. The task in this project was to automate the analysis of microscopic exposures of cornea transplants, calculating their cell density (a quality indicator).

Part of the solution developed is a sequence of steps for processing the images. Beginning with the acquisition of the images, continuing with the classification of the cells, and ending with the graphical and numerical presentation of cell density, we developed this sequence of steps completely in the graphical programming language.

The result of a session with IMAQ Vision Builder is a script giving us a very good overview of the operations to complete. With the generated Builder File, we can immediately develop the application with LabVIEW and Advanced IMAQ Vision. We can completely adopt the list of tasks to complete as is, without making any changes. Within only a few minutes, LabVIEW and Advanced IMAQ Vision generate the application.

Conclusion
We have used this solution at the Hornhaut Bank for the past year to automate the counting and the analysis of the transplants. In the past, we did this manually and our results were, therefore, subject to rather subjective errors. Nevertheless, because this is a very sensitive task, the physician responsible always surveys the operation.

With the help of this solution, we reduced the time needed for transplants analysis considerably, and, because of the direct acquisition of data, we saved in our costs, as well. With IMAQ Vision Builder, we can develop complex measurement and automation solutions at relatively low costs and within an acceptable time frame.

For more information, contact:

Prof. Norbert Dahmen

Tel 02151 / 82 23 55

Fax 02151 / 8 22 60

E-Mail norbert.dahmen@fh-niederrhein.de

Dirk Holzwarth

Tel 02151 / 82 23 55

Fax 02151 / 82 23 33

E-Mail dirkholz@ mpl-server.kr.fh-niederrhein.de

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