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August 25, 2014

Supercomputing Facilitates Breakthrough Cancer Treatment

Tiffany Trader
TACC-ionization-chamber-model

MD Anderson Cancer Center researchers are relying on a powerful supercomputer to develop a dosing protocol for an MRI-guided radiation therapy for cancer care, called MRI-linac. The Lonestar system at the Texas Advanced Computing Center (TACC) is helping researchers fine-tune the radiation dosing mechanism so that just the right amount of radiation is delivered to the tumor, maximizing the sparing of healthy surrounding tissues.

The Elekta and Philips Research Consortium on MRI-Guided Radiation Therapy is advancing the MRI-guided linear accelerator (linac)  to address the limitations of traditional imaging methods based on computed tomography (CT) scans. In cases where the tumor is constantly moving, for example, in concert with the patient’s breathing as would be likely to occur with lung cancer, CT scans don’t provide the necessary real-time component. By combining radiation therapy with magnetic resonance imaging (MRI), MRI-linac enables physicians to view the tumor in real-time with high detail during the radiation treatment. The ability to deliver radiotherapy in such a precise way constitutes a major breakthrough in cancer care.

A group at the MD Anderson Cancer Center, a member of the research consortium, is tracking how much radiation is being delivered through the MRI-linac, part of a discipline known as dosimetry. By carrying out simulations on TACC’s Lonestar, the researchers are able to model radiation in a magnetic field, helping to establish this safer, more effective treatment.

“Precise knowledge of dose is critical to effective radiation treatment,” said Michelle Mathis, a medical physics researcher for the MD Anderson dosimetry team, in an article on the TACC website.

“Different tumors need different doses to be killed,” Mathis added. “Our work focuses on gaining a better understanding of how to precisely calibrate the new MRI-linac system so that the appropriate amount of radiation is delivered to the cancer tumor while healthy tissue is spared.”

The MD Anderson team has so far run simulations comprising 250,000 computing hours on Lonestar. They are working to develop correction factors for 16 different ionization chambers. These chambers detect radiation, providing feedback so that dose can be calibrated. The addition of MRI and the resultant magnetic field affects the way the chambers operate. The team’s solution is to develop correction factors that enable the ionization chambers to be appropriately calibrated.

“Using Lonestar, we are able to simulate the effect of many variables on the ionization chamber readings, which will allow us to precisely calculate radiation dose,” Mathis said.

The MRI-linac system is still in development and is not yet available for sale. However, the research partners have completed work on some of the core components and installation of the first-generation test system is underway. The supercomputing simulations being performed at TACC are critical to ensuring the system works as intended.

Feature coverage of this important innovation comes to us via TACC Science and Technology Writer Makeda Easter.