Prevention of Ground Pad During Radiofrequency Tumor Ablation

描述(申请人提供)：射频消融是一种很有前途的微创热疗方法，用于消融肝、肾、骨和肺癌。在成像引导下，将电极插入肿瘤，并向电极施加射频电流，导致离子搅动和组织加热。一旦肿瘤达到50℃，肿瘤就被凝固性坏死破坏。射频消融的主要优点之一是它可以以微创的方式应用，导致患者快速恢复和低发病率。最初的射频设备使用25W功率，创建了直径1.5厘米的凝固区，而目前的设备使用200-250W功率，创建了直径4-6厘米的凝固区。目前射频设备的一个主要局限性是，由于凝固区的大小不足，即使是中等大小的肿瘤(&gt；3厘米)也不能通过一次消融来治疗。因此，未来的设备可能会继续朝着更大的发电机功率和多个电极的趋势发展，以增加凝固区的大小，减少处理时间。使用更高功率的射频发生器和增加凝固区的一个主要障碍是接地垫加热，在严重情况下可能导致皮肤三度烧伤。目前，对于严重的皮肤烧伤(2度或3度)，磨垫皮肤烧伤的发生率从0.1%到3.2%不等，轻度皮肤烧伤的发生率从5%到33%不等。由于接地垫下面射频电流的不均匀分布，最靠近电极的边缘是最有可能发生皮肤温度最高和烧伤的地方。在临床消融手术中，两到四个接地垫与消融电极等距离放置，通常在大腿周围。在距离电极更远的地方添加额外的接地垫只会带来很小的改善，因为射频电流优先传输到最近的垫。到目前为止，减少与接地垫相关的加热的尝试仅限于优化垫的放置、垫的形状和垫的冷却。我们建议通过顺序地激活接地垫，并在垫下面添加一层导电凝胶来调制每个垫下面的射频电流和相关的加热。因此，RF电流在多个焊盘之间均匀分布，减少了相关加热，并且可以任意放置焊盘，而不受与RF电极处于相同距离的电流限制。这种方法将使发电机功率更高，并减少皮肤灼伤的可能性。该项目与公共卫生的相关性：该项目的成功完成将使肝癌的治疗更加有效。医生将能够治疗更大的肿瘤，治疗次数将减少，成功率可能会提高。

DESCRIPTION (provided by applicant): Radiofrequency (RF) ablation is a promising, minimally invasive heat-based method used to ablate cancer of the liver, kidney, bone, and lung. Under imaging guidance, an electrode is inserted into the tumor, and radiofrequency current is applied to the electrode resulting in ionic agitation and tissue heating. The tumor is destroyed by coagulative necrosis once it reaches >50 ¿C. One of the major advantages of RF ablation is that it can be applied in a minimally invasive fashion, resulting in rapid patient recovery and low morbidity. Initial RF devices used 25 W power and created 1.5 cm diameter coagulation zones, while current devices use 200 - 250 W power and create 4-6 cm diameter coagulation zones. One major limitation of current RF devices is the inability to treat even moderate size tumors (> 3 cm) with a single ablation due to insufficient size of the coagulation zone. Therefore future devices will likely continue the trend towards higher generator power and multiple electrodes to increase the size of coagulation zone and decrease treatment times. A major obstacle in employing higher power RF generators and enabling increased coagulation zones is ground pad heating, which can lead to 3rd degree skin burns in severe cases. The current incidence of ground pad skin burns ranges from 0.1 - 3.2 % for severe skin burns (2nd or 3rd degree), with mild skin burns ranging between 5-33 %. Due to inhomogeneous distribution of RF current below the ground pads, the edge closest to the electrode is where the highest skin temperatures and burns are most likely occur. In clinical ablation procedures, two-to-four ground pads are placed equidistant from the ablation electrode, usually around the thighs. Adding additional ground pads further away from the electrode will only provide minimal improvement, since RF current travels preferentially to the closest pads. Attempts in reducing ground pad related heating so far have been limited to optimizing pad placement, pad shape, and cooling of the pads. We propose to modulate the RF current and associated heating below each pad by sequentially activating ground pads, and adding a layer of electrically conductive gel below the pads. Thereby RF current is distributed evenly among multiple pads, related heating is reduced, and pads can be placed arbitrarily without the current limitation of being at the same distance from the RF electrode. This method will enable higher generator power, and reduce the likelihood of skin burns. Relevance of this project to public health: Successful completion of this project will enable more effective treatment of liver cancer. Physicians will be able to treat larger tumors, treatment times will be reduced, and success rates may increase.