Department of Physics, Toronto Metropolitan University, 350 Victoria Street, Toronto, Ontario, Canada.
Institute for Biomedical Engineering, Science and Technology (iBEST), Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.
Phys Med Biol. 2024 Oct 11;69(21). doi: 10.1088/1361-6560/ad7f19.
A reliable, calibrated, non-invasive thermometry method is essential for thermal therapies to monitor and control the treatment. Ultrasound (US) is an effective thermometry modality due to its relatively high sensitivity to temperature changes, and fast data acquisition and processing capabilities.In this work, the change in backscattered energy (CBE) was used to control the tissue temperature non-invasively using a real-time proportional-integral-derivative (PID) controller. A clinical high-frequency US scanner was used to acquire radio-frequency echo data fromporcine tissue samples andmice hind leg tissue while the tissue was treated with mild hyperthermia by a focused US applicator. The PID controller maintained the focal temperature at approximately 40 °C for about 4 min.The results show that the US thermometry based on CBE estimated by a high-frequency US scanner can produce 2D temperature maps of a localized heating region and to estimate the focal temperature during mild hyperthermia treatments. The CBE estimated temperature varied by an average of ±0.85 °C and ±0.97 °C, compared to a calibrated thermocouple, inandstudies, respectively. The mean absolute deviations of CBE thermometry during the controlled hyperthermia treatment were ±0.45 °C and ±0.54 °C inandrespectively.It is concluded that non-invasive US thermometry via backscattered energies at high frequencies can be used for real-time monitoring and control of hyperthermia treatments with acceptable accuracy. This provides a foundation for an US mediated drug delivery system.
一种可靠、经过校准、非侵入式的测温方法对于热疗至关重要，可用于监测和控制治疗过程。由于超声（US）对温度变化具有相对较高的灵敏度，并且具有快速的数据采集和处理能力，因此它是一种有效的测温模式。在这项工作中，使用反向散射能量（CBE）的变化，通过实时比例积分微分（PID）控制器来非侵入式地控制组织温度。使用临床高频 US 扫描仪从猪组织样本和小鼠后腿组织中获取射频回波数据，同时使用聚焦 US 施加器对组织进行温和的热疗。PID 控制器将焦点温度保持在约 40°C 左右 4 分钟。结果表明，基于高频 US 扫描仪的 CBE 的 US 测温可以产生局部加热区域的 2D 温度图，并估计温和热疗期间的焦点温度。与校准热电偶相比，在和研究中，CBE 估计的温度分别平均变化±0.85°C 和±0.97°C。在受控热疗过程中，CBE 测温的平均绝对偏差分别为±0.45°C 和±0.54°C。结论是，高频反向散射能量的非侵入式 US 测温可用于实时监测和控制热疗，精度可接受。这为 US 介导的药物输送系统提供了基础。
