One of the most common causes for severe pain in patients with cancer comes from cancer metastases. Once the cancer metastasized, the patients often experience chronic pain or other related effects. Even though radiotherapy and chemotherapy is the standard of care for cancer patients, approximately 25% of those patients do not get pain relief. This project was an R&D project for Medtronic, Inc. There are currently several treatment options for painful metastatic disease with RF ablation being the most mature treatment option. One of the disadvantages of RF ablation is its reliance on conduction to spread the heat from the ablation probe to the surrounding tissue. This requires subjecting the patient to a long procedure. Interventional radiologists want shorter procedure times with quicker heating rates and higher temperatures while maintaining the safety profile that RF ablation has (spherical, controlled heating zone around the applicator port).
The challenge was to use higher frequency RF waves to deliver focused energy into the tumor at the greatest efficiency thus minimizing the losses at the device-tissue interface and on the transmission line.