Video Game Graphics Cards Slash Radiation Doses for Cancer Treatment
A CT scan machine.
CREDIT: © Badoff | Dreamstime.com
The same microchips that help render on-screen action in video games could slash the damaging radiation doses cancer patients receive during treatment, according to a new study.
Doctors use computer tomography (CT) scans to create images of bodily tissues beset by tumors in order to better target and kill the cancer with radiation. This image-guided radiation therapy (IGRT), as it's called, lets clinicians precisely locate tumors to hit them with high radiation doses while minimizing radiation damage to surrounding, healthy tissue .
But there is a drawback. Although IGRT achieves improved outcomes compared to traditional radiation treatments, its CT scans still deliver blasts of X-ray radiation of their own to non-cancerous tissues.
In this way, the radiation doled out from the heavy use of CT scans for general medical imaging leads to new cases of cancer.
"CT dose has become a major concern of the medical community," said Steve Jiang, senior author of the study and an associate professor of radiation oncology at the University of California, San Diego (UCSD). "For each year's use of today's scanning technology, the resulting cancers could cause about 14,500 deaths."
Jiang continued: "Our work, when extended from cancer radiotherapy to general diagnostic imaging, may provide a unique solution to solve this problem by reducing the CT dose per scan by a factor of ten or more."
Radical radiation reduction
The simplest way, of course, to limit patients' radiation exposures is to reduce the total number of X-ray scans as well as the amount of radiation in each one. But this tack results in noisy, mathematically incomplete data that takes hours to process using the current bit-by-bit reconstruction approaches.
That time factor is a problem because the CT scans are usually done just prior to a round of radiation as tumors can move around in between treatments, so fast reconstruction is necessary.
The innovative CT reconstruction algorithm devised by the researchers uses a GPU to process data in parallel – increasing computational efficiency and making it possible to reconstruct a CT scan in about two minutes.
With only 20 to 40 X-ray projections, the team achieved images clear enough for tumor-targeting IGRT. The reconstruction time ranged from 77 to 130 seconds on an NVIDIA Tesla C1060 GPU card, depending on the number of projections – an estimated 100 times faster than similar iterative reconstruction approaches, said lead author Xun Jia, a UCSD postdoctoral fellow.
Compared to the currently widely used scanning protocol of about 360 projections with four times the radiation, Jia said the new processing method resulted in 36 to 72 times less radiation exposure for patients.
The reconstruction algorithm is part of the UCSD group's effort to develop a series of GPU-based low dose technologies for CT scans.
"In my mind, the most interesting and compelling possibilities of this technique are beyond cancer radiotherapy," said Jiang.
Jiang, Jia and their colleagues will present their findings this Wednesday at the 2010 annual meeting of the American Association of Physicists in Medicine in Philadelphia, Penn.