A bridge of hope is rising for the future of children’s health, thanks to an NC State professor’s work on improving the accuracy of tests that detect lead in bone.

Dr. Robin Gardner and his colleagues are the first to combine technologies in a way that triples the accuracy of bone lead measurements. The increased sensitivity is important because children normally have very small amounts of bone lead, but are highly vulnerable to lead poisoning, which can cause mental retardation, learning disabilities, nervous system and kidney damage, and other problems that last a lifetime. Although children’s blood is easily tested to determine recent lead exposure, only bone lead tests indicate total lifetime exposure—crucial to understanding the link between lead exposure and children’s developmental problems.

Gardner, a professor of both nuclear and chemical engineering, has invented a novel approach using two kinds of detectors simultaneously—one for K x-rays from lead, and one for L x-rays that are emitted from other metals. Using both detectors at once—called K and L coincidence spectroscopy—increases the accuracy of x-ray fluorescence (XRF) in measuring small amounts of lead in bone. The combination helps screen out the “static” picked up by XRF from other metals in bone, such as calcium, revealing even small amounts of lead.

While the resulting increase in accuracy is significant, Gardner himself says that much more work is needed before the combined technologies can detect precisely the minute amounts of lead in children’s bones. “Before this technique can be used in medical applications, we’ll need another factor of three or four in increased sensitivity,” Gardner said. “We’ll be thinking of being able to measure approximately one part of lead per million parts of bone, rather than ten parts per million.”

That level of accuracy is not too distant, according to Dr. Andrew Todd, Gardner’s colleague and associate professor of Community Medicine at Mount Sinai Medical Center in New York. “We don’t even know what average bone lead is for children now,” Todd said, “but, with extensions of this technology, we’ll know soon.”

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