ABSTRACT
The aim of this work was to optimize the parameters for semiquantitative analysis with regard to the average number of counts per pixel in tomographic projections. The analysed studies were divided into three groups, proportionally, to average the counts per pixel. The analysis of results proved the dependence (P<0.05) between the average geometric contrast of images with the maximum counts per pixel higher than 500, reconstructed with the cut-off frequency fc=0.50fn, and the standard image. Also, the same dependence was found between the group with an average of 200 counts per pixel and the standard image at the cut-off frequency fc=0.40fn. The analysis of the attenuation coefficient, c, showed significant differences. The attenuation coefficient c=0.12 cm-1 as accepted for further studies. Optimization of the matrix order of interpolation filter proved increasing of contrast with decreasing size of the matrix. In conclusion, according to the average number of counts per pixel in a projection the parameters of image reconstruction, particularly the cut-off frequency fc of the Butterworth filter, should be changed. Additionally, an attenuation correction with coefficient c=0.12 cm-1 and interpolation with matrix size equal 7x7 should be applied.
