Giving cancer the needle

A trio of innovations may enable physicians to plan prostate cancer patients’ treatment in real time and to implant cancer-killing radiation “seeds” more accurately and efficiently.

Directionally emitting radioactive sources, a device for placing needles and seeds, and a fast treatment-planning method were developed by UW-Madisonengineering physics professor Douglass Henderson and medical physics associate professor Bruce Thomadsen.

Together, this suite of inventions could mean on the spot treatment reoptimisation, which is said to be the holy grail of prostate cancer seed placement.

To eradicate diseased tissue, physicians implant up to 100 radioactive seeds in the prostate. Like a tiny grain of rice, each seed is cylindrically shaped and emits radiation in all directions-increasing its likelihood of damaging healthy tissue, too.

Borrowing a concept from nuclear materials handling, Henderson and Thomadsen designed directional seeds-sources with vertical shielding along one side. “I think nobody’s done it before because they look at these sources, which are only eight-tenths of a millimetre in outer diameter, and they say there isn’t enough space to put shielding,” says Thomadsen. “We found you can compress things and you can do it.”