Technologies

In microwave ablation, a coaxial microwave antenna is inserted into tissue in or near a tumor to deliver microwave energy to the region and remove the tumor. The specific absorption rate (SAR) pattern of energy deposited into the tumor is a function of microwave power and antenna design.
Currently, single probe percutaneous microwave ablation can only treat relatively small lesions because microwave power to the antenna must be limited; otherwise, excessive backward heating, which could burn skin and damage healthy tissue, might occur due to backpropogation of energy along the antenna (generally referred to as the tail). UW-Madison researchers have developed a novel microwave antenna that uses a floating sleeve to suppress the tail of the SAR pattern, allowing more energy to be delivered locally and evenly to the tumor while reducing the risk of detrimental backward heating. The antenna consists of coaxial antenna conductors surrounded by a floating metal sleeve that is electrically isolated from the antenna by a Teflon layer. The metal sleeve promotes destructive interference of axial microwave energy passing inside and outside of the sleeve, thus suppressing the tail of the SAR pattern and minimizing damage to healthy tissue along the antenna tail.