Experimental Evaluation of a Microwave Imaging System for Muscle Rupture Detection

Sammanfattning: Injuries to the hamstring muscles are one of the most common injuries in sports such as football, sprinting, and running. Imaging plays a key role in diagnosing and managing athletes with muscle injuries, and particularly magnetic resonance imaging is usually required to diagnose muscle ruptures. Unfortunately, this imaging modality is both costly and availability is limited. The aim of this work is to explore the possibility of using a microwave imaging system to aid in the diagnosis of a muscle rupture and eventually supplement or perhaps even replace current imaging modalities. A microwave based imaging system could help improve availability and bring the cost down leading to improved and more accurate diagnostics. The microwave imaging system consist of several antennas placed on a semi circular array. The antennas consists of monopole antennas and a lossy (conductive) gel. The lossy gel serves the purpose of reducing the effects of signals taking undesired paths outside the body under test and improves the image quality. In this work, different gels were manufactured and evaluated in imaging experiments. The results show that the lossy gels can effectively reduce the undesired signals, resulting in significantly more stable and repeatable image reconstructions. The results were consistent in several different imaging experiments with targets of different size and location. Furthermore, a software defined radio (SDR) board was explored and benchmarked against a high-performance Vector Network Analyzer (VNA) with the purpose to assess whether it could be used as a low-cost and compact alternative for the measurements. The measurements showed good repeatability and accuracy for a transmission loss up to 70 dB, with the option to adapt the system gain to handle even higher transmission losses in specific channels