High-intensity focused ultrasound (HIFU) ablation has been widely used in advanced pancreatic cancer in recent years. In numerous studies, HIFU has been shown to be safe, effective, and practicable, but there are a few HIFU-related adverse effects. The patients’ discomfort during therapy increased proportionally with increasing delivered energy and pain levels seemed to be independent of the dose of anesthetic or sedation. If the power used in therapy is too high, the temperature of the target area will rise rapidly, and the boiling and cavitation make the shape of the necrosis area difficult to control. In recent years, moderate-intensity focused ultrasound (MIFU) has also been shown to heat the tumor locally for palliative treatment. Choosing the appropriate power and effectively controlling the tissue temperature until reaching the threshold for thermal necrosis are of great significance for ensuring the safety of palliative treatment. In this study, an infrared temperature measurement experimental system was set up to measure the temperature rise at different power in an ex vivo bovine liver. It was found that when the acoustic intensity of the focused ultrasound was lower than the cavitation threshold (within the range of the MIFU), the temperature of the tissue kept rising at a steady rate and could still reach the thermal damage threshold temperature within tens of seconds. The results showed that the temperature induced by the MIFU was almost entirely dependent on the thermal effect, and the temperature of the tissue at the end of sonication was linearly related to the power. Finally, this study considered the effect of blood perfusion on the temperature for the application of focused ultrasound in the palliative treatment of advanced pancreatic cancer with the goal of providing a reference for the application of focused ultrasound in the palliative treatment of advanced pancreatic cancer.

Accurate temperature distribution measurement during high-intensity focused ultrasound (HIFU) treatment is crucial for avoiding damage to sensitive tissues and organ systems. To surpass the constraints of conventional thermocouple temperature measurement approaches, near-infrared temperature measurement, as a non-invasive imaging method, is proposed. Using infrared glass as a temperature observation window allows for studying the temperature distribution on the surface of biological tissues under ultrasound exposure. The temperature rise in the tissues near the infrared glass under ultrasound exposure was investigated through numerical simulations. Moreover, the effects of the shear waves and thermal viscosity induced by the infrared glass were also analyzed. The results indicate that the shear wave in the glass weakens the intensity of the ultrasound pressure in the focal region while enhancing the efficiency of the acoustic thermal conversion. Thermal viscosity increases the acoustic pressure and temperature in the focal zone. Furthermore, oblique incidence facilitates the transformation of the acoustic thermal effect, caused by shear waves and thermal viscosity, resulting in an expanded temperature rise range on the tissue surface. The non-linear effects in the ultrasound field further enhance the acoustic thermal effect. Significant errors occur in the near-infrared method when utilizing infrared glass for temperature measurement, with the shear waves exerting the most substantial impact on the temperature distribution. These research findings carry substantial implications for optimizing treatment plans, enhancing treatment safety and efficacy, and offering potential application value for temperature control in HIFU treatment.