Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II Etalon-photometric method for measuring the density of the material at X-ray images Saratov, SSU, 2015 Buldakov N.S., Buldakova T.I., Suyatinov S.I.

Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II Application area Traditional Alternative Diagnostics Qualitative assessment of the density is important Treatment method Quantitative assessment of the density is important Analysis of Kidney density in stones and gallbladder analysis Liver density analysis (cirrhosis) Bone density analysis (osteoporosis) Currently, the main method for studying the internal structure of biomedical objects is radiography.

Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II Problem: The physical density evaluation according to X-rays images. Decision: 2. Evaluation of absolute density. We propose an etalon- photometric method. The method is to use an etalon when evaluating the photometric characteristics. 1. Relative density assessment (relative to nearby organs). Although the method gives the result, but in some cases it is insufficient.

Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II Relative density assessment Man intuitively use this method for the diagnosis of diseases. There is a qualitative assessment of the density of one region relative to another. It is necessary to introduce some quantitative characteristics, which can be compared in the image analysis.

The value is related to the optical density of blackening: Formation of the scanned object image on the digitized snapshot I 0 – beam intensity, recorded in the absence of the object scan; – absorption coefficient (unknown function of the coordinates) Suppose that rays penetrate the object being scanned parallel to the axis z. As a result, the intensity I of the beam is reduced after passing the distance l from the point z = 0 to the point of l on the exponential law: Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II - integral index of radiographic density of tissue. It is the main source of information for the elements of X-ray image classification.

Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II For the tissues classification at different images, go to the measurement of the relative integral index of radiographic tissue density: Areas of the image in which the values are calculated by averaging.

Relative density allows you to compare different areas on the radiographic images. However, the quantitative value of the these areas density can not be obtained. The limit of the current applications. Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II As a development of this method the etalon-photometric method was contrived. Indicating the levels of the same density.

Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II stone etalon X-ray Etalon-photometric method It based on the use of an etalon object with a known density. The snapshot must contain an image of two additionally introduced objects with the same known physical density а e and thickness h. The optical density of the blackening is defined as: The physical density of the object: D e+be+b D e D b+s screen

Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II To determine the physical density  s you need to know the thickness z s. Assume that the analyzed object has a round shape. Therefore, at the stage of the image pre-processing we select all objects with such forms. To do this, follow the standard procedure of contrasting and highlighting contours that are implemented with the use of cellular automata. The required thickness is calculated in comparison with the size of etalon. The density calculation can be divided into two generalized stages: 1. Highlighting the areas of interest. Can be performed, for example, by using a filtering algorithm based on cellular automata. 2. Calculation of the physical density of the object using the etalon- photometric method.

1)calculation of the etalon object radiographic density D e whose physical density is known a priori; 2)processing of the original fuzzy image to enhance the contrast; 3)selection of the visible contours on the processed image; 4)choice of the original image point, the density of which we are interested; 5)calculation of the averaged local density in the selected area according to the formula * ; 6)calculation of the ratio of local density to the etalon density; 7)adding a significant feature in the characteristic vector. Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II Form of function F(i,j) * The general algorithm for density estimating at X-ray images:

Saratov Fall Meeting 2015 Computational Biophysics and Analysis of Biomedical Data II The method allows to define the following image characteristics : the densest areas ; the number of close lying objects, similar in density ; the number of lesions ; the position of the lesions ; the area of damage. Method possibilities