فهرست نشریات علمی دسترسی آزاد ایران

Introduction: While high-intensity focused ultrasound (HIFU) is widely used for non-invasive tumor ablation, current models fail to account for the cumulative energy contributions of nonlinear harmonics (up to the 256th order), significantly limiting treatment precision. This study quantifies the role of harmonic superposition (1st+2nd+…+256th order) in regulating HIFU-induced focal temperature and establishes an optimized harmonic combination to enhance clinical parameter design.   Material and Methods: A coupled acousto-thermal model, validated against MRI thermometry, was developed by solving the Westervelt equation and Pennes bioheat equation to simulate nonlinear acoustic propagation and transient temperature fields in ex vivo porcine muscle under HIFU irradiation. Results: The 1st+2nd+...+128th harmonic superposition model achieved <2.2% error in focal temperature prediction across all tested power levels (80–200 W), with errors of 1.6% at 80 W (48.18 °C simulated vs. 47.96 °C measured), 1.1% at 140 W (66.0 °C vs. 65.31 °C), 1.8% at 160 W (77.78 °C vs. 76.38 °C), and 2.2% at 200 W (82.25 °C vs. 84.11 °C). Mid-order harmonics (2nd–64th) contributed 75–80% of energy deposition, while high-order harmonics (>128th, e.g., 256th at 276.48 MHz) exhibited severe attenuation (135× higher than the fundamental wave). The linear propagation model (fundamental frequency only) underestimated temperatures by 4.8-23.9%, highlighting the necessity of nonlinear harmonic inclusion. Conclusion: This work establishes a harmonically optimized framework for HIFU treatment planning, addressing a critical gap in nonlinear acoustic modeling and enabling safer, precision thermal therapy.