UW-Madison team develops new prostate-cancer treatment plan
In one method of treating prostate cancer, called brachytherapy, doctors implant 50 to 100 radioactive iodine-125 or palladium-103 "seeds," each just a few millimeters long, in the gland to eradicate diseased tissue. To plan the seeds' placement for maximum effectiveness and minimal damage to healthy tissue, they map an ultrasound view of the prostate on a 3-D grid, and use optimization software to calculate several sets of possible seed locations and determine which configuration will work best.
Inspired by a reactor physics technique called adjoint- or "backward"-transport, Associate Professor Douglass Henderson, Medical Physics, Engineering Physics and Biomedical Engineering Associate Professor Bruce Thomadsen and graduate student Sua Yoo have developed a method that could reduce the time of this treatment-planning step from as long as 40 minutes to a couple of seconds. Using the adjoint information, they assign a numerical rank to each possible seed location, based on its potential to deliver radiation where it's needed. The greedy algorithm optimization software then computes the best seed arrangement. This method also could make it easier for doctors to plan treatments using combinations of seeds with varied characteristics.