Super Computer Aids Laser-Driven Cancer Therapy

Researchers used a supercomputer to observe atomic scale interactions, which could improve laser-driven tumor removal.

Typically, physicians turn to radiation therapy with x-rays in order to treat cancer. This is used to penetrate the tissue and kill the cancerous cells that are deep in the tumors. However, this method will often damage the healthy tissue surrounding the tumor as well.

To overcome this issue, researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) laboratory explored the possibility of replacing particle accelerators with high-powered lasers.

These lasers could accelerate ions in a short period of time to decrease the distance by several meters to a few micrometers, which are needed to accelerate the ions to therapeutic energies.

"I'm coming from accelerator research and laser physics, and what my team and I have been looking at is how we make best use of the high-power lasers so they can replace accelerators for applications like treating cancerous tumors," said researcher Michael Bussmann.

"This is fundamental physics on the one hand, as the laser pulse rips apart all the matter found in a target, usually a very thin metal foil or a tiny sphere, separating the building blocks of atoms--negatively charged electrons and positively charged atomic nuclei, ions--from each other. This state of matter is called a plasma. On the other hand, it has real applications as well.”

Researchers are using the Cray XK7 Titan supercomputer in order to observe the atomic scale interactions that occur multiple times per second.

"I need to simulate a huge volume of atoms over a very long time scale," Bussmann said. "The only way to do this comes through supercomputing, because the large volume needs a lot of memory, and the long time scales mean I need a lot of computational power, and that is where the GPUs come into play."

Titan uses CPUs and high speed graphics processing units (GPUs) in order to accelerate simulations. The rate of calculations is 10 to 100 times faster than machines that only use CPU.

Previously, lasers were large and costly but new emerging technology is able to make these systems more compact. The electrical energy that is used to operate the lasers can be converted into laser light power. This allows researchers to take a couple hundred laser shots per minute, compared to previous systems that could only take several shots per day.

This new technology is still in the beginning stages and will most likely take several years before it is ready to be used in a clinical setting. This is because researchers still need to conduct more research to increase the energy of the ions in order to reach the deep tumors and to get more control of the beam.

Ions are the best targets because it releases very little of their energy into the tissue. Once they are inside the tumor, it releases the lethal dose of radiation. Ion beams allow researchers to calculate where the ions need to stop in order to precisely release the radiation.

With different collaborations, the team was able to create a realistic 3 dimensional simulation of high power laser interactions with targets that are on the scale.

The team has shown major improvements by using Titan, but Bussmann stresses that there is still a need for improvement with the atomic level physics in the team’s simulations, allowing for improved accuracy.