A new way of processing X-ray information can lower the amount of radiation patients receive during cone beam CT scans by a factor of ten or more, a new study finds.

Cone beam CT scans are vital in locating the tumor during image-guided radiation therapy (IGRT) but the continuous exposure to CT radiation is a source of constant concern for medical professionals and patients, Steve Jiang, an associate professor of radiation oncology at the University of California, San Diego and the study's senior author, told DOTmed News. The concern over radiation exposure is especially problematic for the pediatric population.

"We cannot 'IGRT' children because there is a big chance to have secondary cancers some years later when they grow up," said Jiang. "IGRT cannot be used on children right now, so children cannot receive the most cutting edge radiotherapy because of that reason."
X-ray projections could be reduced, however, the results are problematic. Although changes in the X-ray generator pulse rate, pulse duration and/or the current can reduce the radiation dose, current iterative reconstruction approaches are not sufficient. In addition to being noisy and mathematically incomplete, the data take hours to process. These methods are a problem when it comes to cone beam CT scans, as they are only the precursor to the treatment procedure.

Jiang and his team of researchers developed a new CT reconstruction algorithm using the same processors used for video games, called graphic processing unit (GPU) platforms.

"We were thinking about super computers in the beginning but clinically, it's not feasible because not many clinical departments have access to the super computers," Jiang explained.

"The video game cards have recently become quite popular for scientific computing. They are being used for video games, however, people have started to realize that we can harvest the computing powers from those cards for scientific computing, not only for video games," he said.

Using the new algorithm, researchers only had 20 to 40 total X-ray projections, with a reconstruction time ranging from 77 to 130 seconds. The new method resulted in 36 to 72 times less radiation exposure for patients.

Jiang believes the results can be used to make IGRT safer and available for all populations, including pediatric patients. The findings of the study are particularly vital in the current environment of heightened concern about CT radiation.

"Our solution is not to reduce the usage, our solution is to reduce the dosage per scan," said Jiang.

The findings of the study are being presented at the American Association of Physicists in Medicine meeting being held from July 18 to 22 in Philadelphia, PA.

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