The system, known as the ReMix, is able to pinpoint the location of ingestible implants inside the body by using low-power wireless signals. The researchers tested the system in animal tests and were able to show that they could track implants with centimeter-level accuracy. They suggest that similar systems could one day be used to deliver drugs to different regions in the body.
To test the ReMix system, the researcher implanted a small marker in animal tissues. They tracked its movements using a wireless device that reflected radio signals at the patient. A special algorithm could pinpoint the exact location of the marker. The implant itself does not transmit a wireless signal. Instead, it reflects a signal that is transmitted by the device that is outside of the body.
One of the challenges of using wireless signals is having to compete with signals that bounce off of a human body. These signals are generally 100 million times more powerful than signals that come from the metal marker.
The researchers designed an approach that separates interfering skin signals from the signals that the ReMix is supposed to pick up. Using a small semiconductor device known as a diode, the researchers could mix signals together to filter out skin-related signals.
“The ability to continuously sense inside the human body has barely been a distant dream,” Romit Roy Choudhury, a professor of electrical engineering and computer science at the University of Illinois who was not involved in the research, said in a press release. “One of the roadblocks has been wireless communication to a device and its continuous localization. ReMix makes a leap in this direction by showing that the wireless component of implantable devices may no longer be the bottleneck.”
The ReMix system could be used for proton therapy which involves exposing cancerous tumors with beams of magnet-controlled protons. The new approach means doctors can prescribe higher doses of radiation. However, the approach requires high precision, which means the treatment is limited to only certain cancers.
Regular proton therapy treatment relies on a tumor staying in the same place during the radiation process. If a tumor moves during therapy, healthy areas of the body could be exposed to unnecessary radiation. Using ReMix’s smaller marker could help doctors pinpoint the location of a tumor in real-time to stop radiation treatment or to direct the proton therapy beam to the right position.
The MIT CSAIL-developed ReMix system is not yet available for clinical use, according to the researchers. In order for it to be used in a clinical setting, the system would have to have a margin of error closer to a couple of millimeters.
The researchers hope to improve the device by combining wireless data with medical information like MRI scans to improve accuracy. They also hope to further develop the algorithm to account for different body types.
“We want a model that’s technically feasible, while still complex enough to accurately represent the human body,” Deepak Vasisht, lead researcher on the study, said. “If we want to use this technology on actual cancer patients one day, it will have to come from better modeling a person’s physical structure.”
ReMix was developed as part of a collaboration with Massachusetts General Hospital researchers. The group of researchers suggest that the system could be used to enable more widespread use of proton therapy centers.
“One reason that [proton therapy] is so expensive is because of the cost of installing the hardware,” Vasisht said. “If these system can encourage more applications of the technology, there will be more demand, which will mean more therapy centers, and lower prices for patients.”
The research was funded partially by Sumitomo Heavy Industries.