Safety of neutron, gamma testing equal to conventional imaging

Gamma and neutron imaging could be higher quality imaging options than existing techniques like X-ray and computed tomography, while delivering safety levels on par with conventional imaging, according to a study in the June issue of Medical Physics.

The advantage of such new techniques--neutron-stimulated computed tomography and gamma-stimulated emission computed tomography--is that they hold the potential to help detect cancer earlier without having to perform an invasive biopsy, according to researchers led by Anuj Kapadia, an assistant professor of radiology at Duke University School of Medicine.

Conventional imaging modalities like X-ray and CT are used to detect the size and shape of an targeted anatomy; when used to detect cancer, tumors have to be large enough to be detected so that a biopsy can be performed. 

One question that needs answering, the researchers noted, was the safety levels associated with gamma and neutron radiation. Using detailed simulations, it was estimated that the amount of radiation delivered to the liver and breast using both imaging techniques, and found that most radiation was delivered directly to the targeted organ. They also found that a much lower dose of radiation was absorbed by tissue outside of the targeted area.

In the simulated breast scans, the dose to the breast accounted for 96 percent of the radiation in neutron scans and 99 percent in gamma scans, with the heart and lungs receiving less than 1 percent of the radiation dose.

The results weren't as promising for liver scans. The researchers found that the neutron scan was able to deliver he highest radiation dose to the liver, but that with gamma scans the stomach wall absorbed most of the radiation.

"The results show that despite the use of a highly scattering particle such as a neutron, the dose from neutron imaging is on par with other clinical imaging techniques such as X-ray CT," Kapadia said in an announcement. "Neutron and gamma radiation may become viable imaging alternatives if further testing proves them to be safe and effective."

To learn  more:
- see the study
- read the announcement