Microwave hyperthermia aims at selectively heating cancer cells to a supra-physiological temperature. For internal tumors, this is currently achieved by means of an antenna array equipped with a proper cooling system (the water bolus) to avoid overheating of the skin. The planning of the administered heating is usually tackled by finding the antenna feedings that maximize the specific absorption rate (SAR) inside the tumor. However, it might happen that an optimal power deposition on the target does not lead to an equally satisfying temperature focusing. In this paper, we discuss that this is due to the thermal boundary conditions dictated by the external cooling system, and we propose a strategy to overcome this effect. The procedure is still phrased in terms of an optimization of the SAR, but with an additional algorithm to determine a corrected SAR focusing location that maximizes the actual temperature coverage of the tumor. The procedure is thus applicable to existing SAR-based planning approaches; it involves multiple, parametric solutions of the bioheat equation, and appears to require a very limited computational load. Application of this strategy to a tumor in the 3D head and neck region is presented to show the effectiveness of the approach.

中文翻译：

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通过基于预校正 SAR 的聚焦在微波癌症热疗中进行温度聚焦

微波热疗旨在选择性地将癌细胞加热到超生理温度。对于内部肿瘤，目前这是通过配备适当冷却系统（水丸）的天线阵列来实现的，以避免皮肤过热。管理加热的规划通常通过找到使肿瘤内的比吸收率 (SAR) 最大化的天线馈电来解决。然而，目标上的最佳功率沉积可能不会导致同样令人满意的温度聚焦。在本文中，我们讨论了这是由于外部冷却系统规定的热边界条件造成的，我们提出了一种克服这种影响的策略。该程序仍然是根据 SAR 的优化来表述的，但使用额外的算法来确定校正后的 SAR 聚焦位置，从而最大化肿瘤的实际温度覆盖范围。因此，该程序适用于现有的基于 SAR 的规划方法；它涉及生物热方程的多个参数解，并且似乎需要非常有限的计算量。展示了将该策略应用于 3D 头颈部区域的肿瘤以显示该方法的有效性。