Needle-Sized Wireless Device Created to Track Tumors, Radiation Dose

Babak Ziaie, an associate professor in the School of Electrical and Computer Engineering and a researcher at Purdue University's (West Lafayette, IN, USA) Birck Nanotechnology Center.

Dr. Ziaie is leading a team that has evaluated a prototype wireless implantable passive micro-dosimeter and reported that the device could be in clinical trials in 2010. "Because organs and tumors shift inside the body during treatment, a new technology is needed to tell doctors the exact dosage of radiation received by a tumor,” Dr. Ziaie said.

The prototype is enclosed in a glass capillary small enough to inject into a tumor with a syringe, according to Dr. Ziaie. Research findings were detailed in an article appearing in the June 2007 issue of IEEE Transactions on Biomedical Engineering. The article was written by doctoral student Chulwoo Son and Dr. Ziaie.

Whereas conventional imaging systems can provide a three-dimensional fix on a tumor's shifting position during therapy, these methods are difficult to use during radiation therapy, are costly and sometimes require X-rays, which can damage tissue when used repeatedly, according to Dr. Ziaie said.

The new device uses radio frequency identification (RFID) technology, which does not emit damaging X-rays. The device has no batteries, is activated with electrical coils placed next to the patient, and contains a miniature version of dosimeters worn by workers in occupations involving radioactivity. The tiny dosimeter could provide up-to-date information about the cumulative dose a tumor is receiving over time.

"It's a radiation dosimeter and a tracking device in the same capsule and will be hermetically sealed so that it will not have to be removed from the body,” Dr. Ziaie said. The same researchers in 2006 reported findings on the first such miniature device. However, Dr. Ziaie reported that the earlier prototype lacked sufficient sensitivity, was too large, and not suitable for easy implantation.

New findings revealed the development of a miniaturized and more sensitive dosimeter that can be implanted using a hypodermic needle. Researchers tested the prototype with radioactive cobalt. Over that next two years, the engineers will work to simplify the fabrication process so that the devices could be manufactured inexpensively.

A major advantage of the technology is that it does not require complicated circuitry, which could make the device easier and less expensive to manufacture than designs that are more complex. The system consists of simple electronic devices called capacitors and coils.

The device has a diameter of approximately 2.5 mm and is about 2 cm long, making it small enough to fit inside a large-diameter needle for injection with a syringe. The current size is small enough to be used in tumors, but researchers will work to shrink the device to about half a millimeter in diameter and to half its current length, roughly the size of a rice grain, according to Dr. Ziaie.


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