Abstract

Content

Introduction

It is known that the main principle of treatment of fractures of the lower jaw is repositioned and reliable fixation of bone fragments for the duration of bone healing. To do this, use orthopedic and surgical fixation of bone fragments of the mandible.

Osteosynthesis — (al-Greek Òστεον — bone; σúνθεσις — joint, compound) surgical repositioning of bone fragments using various locking structures to ensure long-term elimination of their mobility. The purpose of fixation - providing a stable fixation of bone fragments in the correct position while maintaining the functional axis of the segment, the stabilization of the fracture zone until the seam. As fixatives commonly used pins, nails, screws, needles etc., made of materials having biological, chemical and physical inactivity,.

Proper pre-selection and placement options titanium plates will reduce the time of the operation of osteosynthesis, as well as the inappropriate fusion of fragments and related surgical complications.

Developed by SCS aims to help the doctor during surgery osteosynthesis, namely improving the visibility of the process of selection of titanium plates [1] by constructing a three-dimensional model of maxillofacial area, as well as the calculation required for the selection of anatomic and topographic parameters.

1. Theme urgency

In recent decades, a marked trend of increasing cases of total injuries, including injuries and maxillofacial region. Despite the existence of a multitude of ways osteosynthesis of the mandible and a variety of clamps used at the same time the number of complications such as bone festering wounds, traumatic osteomyelitis, vicious union of bone fragments, the formation of false joints, remains high [1]. One of the reasons for complications in the treatment of fractures of the lower jaw is unstable fixation of bone fragments, resulting in the displacement of the fragments and the violation of the anatomical integrity of the damaged bone, which leads to a change of normal relationships of dentition, and functions of the masticatory muscles.

The likelihood of such problems can be reduced by creating a three-dimensional model of SCS build maxillofacial region. In the presence of such a model, a doctor is able to more accurately assess the anatomical parameters of each clinical case, the limits and characteristics of damage, to plan and evaluate the results of surgery [2].

2. Goal and tasks of the research

The aim of this work is the design of specialized computer systems of building three-dimensional model of the maxillofacial region according to the SCT and determine the necessary parameters for the preparation of osteosynthesis.

Developed specialized computer system should:

  1. Being a full-fledged independent application;
  2. Giving the ability to open the DICOM files without converting them;
  3. The array of shots (results SCT) to build a three-dimensional model of maxillofacial area;
  4. Determine the anatomic and topographic parameters for the selection of titanium plate from its own database and to offer the most suitable option in this case;
  5. Enable visual assessment of accommodation chosen titanium plate;
  6. To issue the results of the survey and selection in a convenient form for the doctor.

In the course of this work seeks to achieve the following objectives:

  1. General analysis of the subject of research and problem statement;
  2. Review and analysis of existing systems and development, which are associated with the processing of images of the maxillofacial area;
  3. Review, analysis and selection of image processing methods;
  4. Analysis and selection of methods for constructing a three-dimensional model;
  5. Development of the structure of SCS, the definition of its subsystems and functional units;
  6. Choice of software development environment accordingly to the task and chosen methods;
  7. Creating SCS and its testing in real conditions;
  8. Analysis of the results obtained when using SCS.

3. Image processing techniques used in the master's work

According to the source image format. Dcm supposed to define the parameters for the selection of titanium plate - the length and width of the area of the fracture, the degree of curvature of the surface of a damaged jaw [10]. This requires pretreatment of the source image in order to maximize quality.

The task of processing the original image can be reduced to the following steps:

  1. Adjust brightness and contrast;
  2. Filtering;
  3. Binarisation;
  4. Erosion or capacity, depending on the prevalence in the neighborhood of the current pixel pixel background or object;
  5. Edge detection.

3.1 Мedian filtering

As a method of filtering the original image median filtering method is chosen as the method in contrast to the linear approaches remains undistorted sharp edges of objects, effectively suppressing noise and small-sized parts [3]. When using a two-dimensional median filtering window (aperture filter), usually in the central symmetry, with its center located at the current location filtering.

Examples of windows while median filtering

Figure 1 – Examples of windows while median filtering

Denote a working sample in the form of a one-dimensional array Y = (y1, y2, ..., yn); number of elements equal to the size of the window, and their location is arbitrary. If you order a sequence Y in ascending order, then it will be the median of the sample cell, which occupies a central position in the collating sequence. Thus obtained by filtration and the product of the current block point.

3.2 The median threshold binarization

Then process the filtered image by the median threshold binarization. The method is as follows: all of the pixels are divided into two classes: the "background" (pixel value 0) and the "object" (pixel value 1).

(1)

In this case, the threshold f0 is chosen as the average brightness of the image being processed by.

3.3 Erosion and capacity

The next step is to apply the method to an image or erosion capacity depending on the predominance of pixels around the current pixel is a background or an object [3]. Erosion of the object leads to the replacement value of its boundary pixels to 0. Single use of the erosion removes the outline of the image 1 pixel. This operation allows you to expand the image and fine lines to separate one object from another, such as fragments of bone in the case of a fracture.

Capacity of the object leads to the replacement of the pixel values of the background adjacent to the object by 1. A single administration of increasing adds a layer to the object 1 pixel. The transaction resulted in lost fine lines background on the subject.

Single use erosion or capacity typically does not provide the desired results. However, the integrated use of these methods allow to maximize the effectiveness of each of them.

The use of erosion and capacity

Figure 2 – The use of erosion and build-up. a) starting a fragment b) applying erosion operation, c) application of the operation capacity

3.4 Sobel edge detection operator

In order to ensure the integrity of the object allocation is performed on the circuit binarizirovannom image. In this case, place the passage of the contour lines in the image clearly, so the choice of method of allocation boundaries depends only on the speed of its implementation. Apply to the image Sobel operator [11]. The operator uses the 3×3 kernel, which fold original image to calculate the approximate value derived by horizontally and vertically. Let A be the original image, and G x and G y - two images, where each point contains the approximate derivatives with respect to x and y. They are calculated as follows:

(2)
(3)

Each image point approximate value of the gradient can be calculated by the following formula:

(4)

Sobel operator is based on the convolution integral filters with small images in the vertical and horizontal directions, so it is relatively easy to calculate. On the other hand, it uses the gradient approximation is quite rough, especially affecting the high-frequency oscillations of the image.

Appearance of the image after performing the above is shown in Figure 6

The result of processing (animation: 5 shots, 5 reps, 35 KB)

Figure 3 – The result of processing (animation: 5 shots, 5 reps, 35 KB)

Conclusion

In this paper we consider the sequence of actions to improve data quality spiral CT to determine the morphological changes Chloe in preparation for osteosynthesis. On Getting a better picture in the future it is planned to determine the parameters necessary for the selection of titanium plate, - the length and width of the area of the fracture, the degree of curvature of the damaged surface of the mandible.

The planned SCS of construction of a three-dimensional model will reduce the chance of complications from improper selection of clips, as on this model, the doctor is able to more accurately assess the anatomical parameters of each clinical case, the boundaries and characteristics of damage, to plan and evaluate the results of surgery.

This master's work is not completed yet. Final completion: December 2013. The full text of the work and materials on the topic can be obtained from the author or his head after this date.

References

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