HIFU Power Monitoring Using Combined Instantaneous Current and Voltage Measurement.
HIFU Power Monitoring Using Combined Instantaneous Current and Voltage Measurement.
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使用瞬时电流和电压组合测量进行 HIFU 功率监控。
DOI：
10.1109/tuffc.2019.2941185
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Adams C
中科院分区：
文献类型：
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作者：
Adams C
在高强度聚焦超声（HIFU）治疗过程中，重要的是要监测输送到换能器的电功率，以避免照射不足或过度照射，确保患者安全，并保护换能器本身。由于易于测量，换能器的电位差可以作为功率输送的指标。然而，即使当换能器的复阻抗在小幅度下被很好地表征并且使用匹配网络时，仅电压（VO）监测也不能解释驱动波形失真、声学路径的改变或换能器的损坏的存在。在这项研究中，提出了组合电流和电压（CCV）作为磁共振成像（MRI）兼容，微型替代双向功率耦合器，这是与开关放大器兼容。对于CCV功率测量，将电流探针数据乘以电压波形并在频域中积分。考虑换能器效率来预测声功率。用辐射力天平（RFB）对该技术进行了验证。当使用典型的HIFU换能器和放大器时，VO预测和声功率的最大差异为20%。但在相同条件下，CCV最大差异仅为5%。该技术被应用到几个病变实验，结果表明，当VO被用作两个放大器之间的控制，有高达38%的病变面积的差异。一旦使用CCV，这大大降低到最大5%。这些结果表明，CCV可以准确地预测实时电功率输送，从而实现更安全的HIFU治疗。
During high-intensity focused ultrasound (HIFU) therapy, it is important that the electrical power delivered to the transducer is monitored to avoid underexposure or overexposure, ensure patient safety, and to protect the transducer itself. Due to ease of measurement, the transducer's potential difference may be as an indicator of power delivery. However, even when a transducer's complex impedance is well characterized at small amplitudes and matching networks are used, voltage-only (VO) monitoring cannot account for the presence of drive waveform distortion, changes to the acoustic path, or damage to the transducer. In this study, combined current and voltage (CCV) is proposed as a magnetic resonance imaging (MRI)-compatible, miniature alternative to bidirectional power couplers, which is compatible with switched amplifiers. For CCV power measurement, current probe data were multiplied by the voltage waveform and integrated in the frequency domain. Transducer efficiency was taken into account to predict acoustic power. The technique was validated with a radiation force balance (RFB). When using a typical HIFU transducer and amplifier, VO predictions and acoustic power had a maximum difference of 20%. However, under the same conditions, CCV only had a maximum difference of 5%. The technique was applied to several lesioning experiments and it was shown that when VO was used as a control between two amplifiers, there was up to a 38% difference in lesion area. This greatly reduced to a maximum of 5% once CCV was used instead. These results demonstrate that CCV can accurately predict real-time electrical power delivery, leading to safer HIFU treatments.