Wireless dosimeter

Engineers at Purdue University are creating a wireless device designed to be injected into tumours to tell doctors the precise dose of radiation received and locate the exact position of tumours during treatment.

The information would help to more effectively kill tumours, said Babak Ziaie, an associate professor in the School of Electrical and Computer Engineering and a researcher at Purdue's Birck Nanotechnology Center.

Ziaie is leading a team that has tested a prototype 'wireless implantable passive micro-dosimeter' and said the device could be in clinical trials in 2010.

'Because organs and tumours shift inside the body during treatment, a new technology is needed to tell doctors the exact dosage of radiation received by a tumour,' Ziaie said.

The prototype is enclosed in a glass capillary small enough to inject into a tumour with a syringe, said Ziaie, who has a dual appointment in Purdue's Weldon School of Biomedical Engineering.

Whereas conventional imaging systems can provide a three-dimensional fix on a tumour'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, Ziaie said.

The new device uses radio frequency identification (RFID) technology, which does not emit damaging X-rays.

The device, which has no batteries and will be activated with electrical coils placed next to the patient, 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 tumour 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,' Ziaie said.

The device has a diameter of about 2.5mm and is about 2cm 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 tumours, but researchers will work to shrink the device to about half a millimetre in diameter and half its current length, roughly the size of a rice grain.