Taking radiotherapy soundings

Radiotherapy is an essential part of cancer treatment, but it is difficult to ascertain precisely how much radiation a tumour has received. In a bid to solve this problem, engineers at Purdue University, Indiana have invented a monitoring device that will be implanted directly into the tumour.

Babak Ziaie of the department of electrical and computer engineering explained that, currently, the only way to measure the doses is to insert a device with a wire into the tumour, which is painful. 'By the end of the summer, we will have a prototype that can be put directly into the tumour with a hypodermic needle.'

The device is extremely simple. It has no battery, and contains just a coil and a capacitor. It works on the same principle as the electret microphone, where a membrane moves in response to soundwaves, increasing and decreasing capacitance in the gap between the membrane and a metal plate.