PSI - Issue 65

Galina Eremina et al. / Procedia Structural Integrity 65 (2024) 92–96 Galina Eremina, Alexey Smolin/ Structural Integrity Procedia 00 (2024) 000–000

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conditions; (b) cross-section with material designations.

The lower layer of the sample automata remained motionless. The effect of shock wave action in the range from 0.01 to 0.2 mJ/mm 2 , 100 pulses, frequency 50 kHz was studied. Changing the energy flux density at the same pulse time has a significant effect on the size of the region with compressive stresses greater than 40 kPa, in which suppression of cancer cells is possible (Fig. 2). Based on the analysis of the hydrostatic pressure distribution fields taking into account the cancer cell suppression criterion (40 kPa), it was found that with low-intensity therapeutic shock wave action of 0.02 mJ/mm 2 and 0.05 mJ/mm 2 in the tumour, the condition for autodestruction of cancer cells is observed in the volume of 0.9 and 1.2%, respectively, in the surrounding bone matrix - 2 and 3%, respectively. With low-intensity therapeutic shock wave action, the maximum amplitude of hydrostatic pressure does not reach 2 MPa, which is much lower than the strength criterion (Fig. 3b). Thus, it was shown that low-intensity therapeutic shock wave exposure does not contribute to statistically significant deactivation of cancer cells in the tumour, but can contribute to stopping the spread of the neoplastic process into the surrounding tissues (Fig. 3a). With medium-intensity therapeutic shock wave exposure with an energy flux density of 0.05 mJ/mm 2 and 0.1 mJ/mm 2 in a cancer tumour, the cell destruction condition is observed in the volume of 5 and 7%, respectively, in the surrounding bone matrix 9 and 13%, respectively (Fig. 3 b). With medium-intensity therapeutic shock wave action directly in the tumour area and the surrounding bone matrix, the maximum amplitude of hydrostatic pressure does not reach 9 MPa at 0.05 mJ/mm 2 and 11 MPa at 0.1 mJ/mm 2 in the areas of load application, which is close to the strength values that lead to degradation of bone tissue near the applicator

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cancellous tissue tumor tissue

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Thus, medium-intensity acoustic action contributes to the deactivation of cancer cells in the tumor and prevents the spread of cancer cells to the surrounding tissues, but can contribute to damage when the applicator is located directly near the tumour. With high-intensity acoustic action, conditions for suppression of cancer cells are observed in 10% of the tumour volume and more than 20% of the volume of the surrounding bone matrix (Fig. 3c). However, the maximum amplitude of hydrostatic pressure significantly exceeds the strength data, which in turn contributes to significant destruction of bone tissue in the surrounding matrix. The obtained results are consistent with experimental data Palmero et al. (2006); Luo et al. (2021); Elkashef et al. (2021). However, the above-mentioned studies lack information on possible damage to the bone matrix surrounding the tumour. Fig.3.Result of simulation SWT on the bone with tumor on mesolevel: (a) compressive stress distribution (kPa) in a model sample under SWT with EFD of 0.15 mJ/mm 2 ; (b) Histogram of the dependence of volume with conditions for stopping the growth of the neoplastic process in the bone matrix (BM) and cancerous tumor (Cancer); (c) Histogram of the dependence of the maximum amplitude of hydrostatic pressure on the intensity of shock wave therapy (1 - maximum amplitude of hydrostatic pressure, 2 - the strength of bone tissue).

3. Conclusions

This paper presents a numerical study of the mechanical behaviour of the mesovolume of bone tissues with tumour tissues under conditions of shock wave loading therapy. The obtained results indicate the effectiveness of