New X-ray Delivery Method Promising

The technique, microbeam radiation therapy (MRT), previously used a high-intensity synchrotron x-ray source such as a superconducting wiggler at Brookhaven’s National Synchrotron Light Source (NSLS) to produce parallel arrays of very thin (25 to 90 micrometers) planar x-ray beams instead of the unsegmented, broad beams used in conventional radiation treatment.

MRT has the ability to control malignant tumours in animals with high radiation doses while subjecting adjacent normal tissue to little collateral damage. But the technique has limitations. For one thing, only certain synchrotrons can generate its very thin beams at adequate intensity, and such facilities are available at only a few research centres around the world.

“The new development seeks a way out of this situation,” explained Avraham Dilmanian from the U.S. Department of Energy’s Brookhaven National Laboratory, lead author of the new study. In the paper, the scientists report results that demonstrate the potential efficacy of significantly thicker microbeams, as well as a way to “interlace” the beams within a well-defined “target” inside the subject to increase their killing potential there, while retaining the technique’s hallmark feature of sparing healthy tissue outside that target.

For example, they exposed the spinal cords and brains of healthy rats to thicker (0.27 to 0.68 millimeter) microbeams at high doses of radiation and monitored the animals for signs of tissue damage. After seven months, animals exposed to beams as thick as 0.68 millimeter showed no or little damage to the nervous system.

“This demonstrates that the healthy-tissue-sparing nature of the technique stays strong at a beam thickness that is within a range that could be produced by specialized x-ray tubes of extremely high voltage and current,” Dilmanian said. Such x-ray sources may become available sometime in the future and may allow the implementation of the method in hospitals.; Source: DOE/Brookhaven National Laboratory