## 4 Discussion
### On the Rational Choice of Parameters of X-ray Computed Tomography  
The objects of control in the problem under consideration are characterized by low radioscopic transparency, at least for one of the angles.  
Let us consider several ideas regarding the choice of parameters of the X-ray computed tomography system from the condition of minimizing the influence of the analyzed factor on the quality of the reconstructed images of the sections of the test object. The analyzed factor is the level of radioscopic transparency, which, when it decreases, leads to the appearance of metal artifacts on the final tomographic images. These metallic artifacts appear on the images in the form of several divergent bands for single, almost opaque local fragments and form a stellate structure for a complex of such local fragments (see Figures 4-6). These stripe or stellate structures are transformed as the radioscopic transparency of objects increases as a result of changes in the parameters of the X-ray computed tomography system.  
It was noted above that, in the last decade, there has been a tendency for computed tomography to transform from a means of visualizing the internal structure of objects into a means of measurement. In this situation, it is especially necessary to develop a criterion for choosing X-ray computed tomography parameters in order to reduce metal artifacts.  
The main interest of research is related to metal artifacts, so we will correct the metal artifact measure (19) by changing the interpretation of the concept of \"ideal\" distribution. In the problem we are considering, taking into account the trends noted above, it is logical to consider a pointwise criterion for the closeness of real \(\mu_{R}(x,y)\) and \"ideal\" \(\mu_{id}^{*}(x,y)\) linear attenuation coefficients. Here, the \(\mu_{id}^{*}(x,y)\) reconstructed distribution of linear attenuation coefficients from projections (17) obtained for theoretically calculated radioscopic transparencies (15)--for counting and (16)--for integral registration modes is taken as. The specified transparencies are calculated for the same values of maximum energy \(E_{\text{max}}\); for the \"ideal\" linear attenuation coefficient, calculations are carried out for \(k_{\text{ADC}}\approx\infty\) and \(N_{0}\approx\infty\).  
Let \(\mathbf{Q}\) be a set of triples \(\mathbf{q}=(N_{0},E_{\text{max}},k_{\text{ADC}})\), and then as a criterion for the rational choice of X-ray computed tomography parameters, we can propose a solution to the following inequality  
\[\max_{(x,y)\in\mathbf{R}}|\mu_{R}(x,y,\mathbf{q})-\mu_{id}^{*}(x,y,\mathbf{q}_ {0})|\leq\Delta_{\text{lim}}, \tag{28}\]  
Here \(\mathbf{q}_{0}=(\infty,E_{\text{max}},\infty)\); \(\Delta_{\text{lim}}\)--given the level of deviation error of linear attenuation coefficients.  
The solution of inequality (28) will be some subset \(\mathbf{Q}_{0}\), \(\mathbf{Q}_{0}\subset\mathbf{Q}\). The specific choice of the required triplet of parameters is carried out by the developer of X-ray CT based on the market of scientific equipment. In this case, it is necessary to take into account the admissibility of the degree of increase in the absorbed energy \(k_{ab}\).