EIT Medical Imaging Device (Senior Design Project)

For my senior design project at UT, our team set out to construct a medical imaging device prototype using Electrical Impedance Tomography. Our aim was to design a prototype which could be made compact, portable, and simple for a non-technical end user (such as a doctor) to operate. The results had to be fast (at or near real time), accurate enough to be used for diagnosis, and simple for the user to interpret. This last requirement is crucial for emerging medical technology, as often medical imaging results require years of instruction and experience to reliably be used for diagnosis.






EIT is a technology that has been around for several decades but is only now beginning to find use, due to the lack of sufficient computing power, micro-controller speed, and data sampling speed and accuracy until recently. The basic premise of EIT is that low power electrical waveforms are sent in patterns through a series of electrodes surrounding the object under test; the impedance of the object's interior alters the waveforms, and the resulting signals are sampled and analyzed, with the result being a visual impedance map of the cavity.

EIT is non-invasive and offers many significant benefits over traditionally used medical imaging technologies, such as MRI and X-Rays. Unlike MRI machines, the systems built around EIT are small (desktop sized or smaller) and inexpensive (the computer typically being the most expensive component), and unlike X-Rays EIT devices use no harmful radiation, only very low power electrical signals. The downsides to EIT right now are the lower accuracy of the resulting images, but this is primarily tied to the previously mentioned hurdles (power of the computer, speed of the embedded system, and accuracy of the Analog to Digital Converters). It is finding use in numerous fields such as oncology, post-surgical embolism detection, and even industrial process monitoring.

Below are two videos of our EIT device in action. First is a simple demonstration of the dynamic responsiveness of the tank, with examples of a insulator and a conductor. The second video is a demonstration in which we use salt to increase the background conductivity of the tank, and then recalibrate the system to show how it responds to differing levels of base conductivity.




Below are copies of our final report and presentation. The presentation includes several videos demonstrating the effect of conductive/insulative materials on the electrical waveforms.

• Final Report [.docx]
• Final Presentation [.zip]