Portable Electromagnetic Knee Imaging System

The high rate of knee injuries among athletes and other people and the need for early onsite detection to avoid severe ligament tear highlight the necessity of a portable knee imaging tool. Thus, an electromagnetic system based on a multistatic radar to image knee injuries is introduced. The system includes an antenna array of eight printed biconical elements, which have wide operational bandwidth of 103.4%, covering the band 0.7–2.2 GHz, and unidirectional radiation with a high front-to-back ratio for improved imaging. The antenna array is placed on movable holders around the knee to ensure equal distances from its boundaries. The antenna is assessed in terms of simulated and measured near- and far-fields, along with electromagnetic wave penetration into the knee. The complete system is built and experimentally validated on in-house built durable, realistic knee phantoms, which emulate normal and injured cases. To reconstruct knee images, a modified multistatic confocal algorithm is used. Since the left and right knees of humans are mirror-symmetrical, the modified algorithm uses a differential approach to remove signal clutters, multistatic coherence factor to improve the quality of channels, and applies dielectric mapping to reduce detection error. The images indicate the ability of the system to detect different types of ligament tears with an accurate localization.