A new device out of MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL), dubbed ReMix, could make it easier to track the location of objects inside the human body. Though it has nothing to do with satellites, the technology does for objects in the body what GPS does for cars: tells the user where they are. Hence MIT calls this a "GPS for inside your body."

Using a combination of ingestible implants and low-power wireless signals, the team members demonstrated that they can track those implants down to 1.4 cm inside animal tissue – specifically dead chickens, ground chicken and pork belly, which the researchers say are ideal for emulating human tissues.

The work addresses the challenges posed by human bodily tissues, which scatter and cause interference to any wireless signals sent.

"The ability to continuously sense inside the human body has largely been a distant dream," says Romit Roy Choudhury of the University of Illinois, in an MIT 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." Professor Choudhury was not involved in MIT's research.

The ReMix system involves implanting a small marker into the tissue then using a wireless device to track movement in the body. A more precise location can then be determined by use of algorithms designed specifically to address the interference caused by body-matter. The marker itself simply reflects the signal transmitted by a device outside the body, eliminating the need for an external energy source.

The researchers say the technology could be used to deliver medicine to particular parts of the body. One area the team highlights is proton therapy, a type of radiotherapy used in the treatment of cancer.

The scientists hope their work could contribute to wider adoption of proton therapy, reducing costs for patients. At the moment there are only around 100 proton therapy centers in the world. The team also hopes the technology could reduce the need for surgery and invasive endoscopes, and save money in the process.

With only centimetre-level accuracy being achieved so far, there is some way to go before it could be used in a clinical setting, not to mention the need to test the technology in live subjects. The work may now focus on combining the wireless data with other medical data, such as MRI scans. There's also the issue of how complex and different human bodies are, so work will need to go into refining the algorithms to accommodate our various shapes and sizes.

"We want a model that's technically feasible, while still complex enough to accurately represent the human body," lead author Deepak Vasisht explains. "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."

The MIT team worked in collaboration with Massachusetts General Hospital. The research was led by CSAIL's Dina Katabi.

The team's research is due to be presented at the Association for Computing Machinery's Special Interest Group on Data Communications in Budapest this week.

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