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New lens could help find cancer tumors earlier

A new approach to cancer detection is being developed at Argonne National Laboratory

Argonne scientist Bob Smither invented a gamma-ray lens so precise that it could help detect tumors as small as a grain of rice. (Argonne National Laboratory photo by George Joch)

August 20—The new lens technology, developed by scientists at Argonne's Advanced Photon Source, uses gamma rays diffracted by a set of 828 copper crystal cubes arranged in 13 concentric rings in a disk slightly smaller than a dinner plate. The lens focuses the gamma radiation emitted from a small radioactive source in the body of a patient into a small, well-shielded detector.

This application is simulated by placing a small radioactive source in a "phantom"—an acrylic plastic device designed to simulate areas of the human body—and scanning the phantom with the lens system. The technology can pick up mildly radioactive tracers as small as a dill seed.

"The key is sensitivity and special resolution," says developer Bob Smither. In addition to picking up the smaller sized tumor, the technology can also pinpoint its location within a millimeter or two.

Most cancers are presently found with gamma cameras, which provide images of potential tumors in the body by detecting the radiation emitted by a radiopharmaceutical given to a patient undergoing a full-body scan.

Suspected tumor regions collect higher concentrations of the radiopharmaceutical, which produces a higher count rate and therefore a detectable contrast between the tumor region and its surroundings.

The Argonne-developed lens is designed to supplement full-body scans done with a gamma camera. The gamma lens could be used following the full-body scan to reveal additional detail about suspect areas found during the scan, which means no additional radiopharmaceutical would be needed.

The device, set up as a six-lens array, will detect tumors as small as two millimeters in diameter, Smither said. "Moreover, it can provide sufficient information to determine the location of a tumor accurately in three dimensions, and thereby eliminate the uncertainties in the full-body scan," he added.

Smither estimates the cost of the instrumentation to be less than $100,000, making it affordable to medical facilities of all sizes.

In addition, Smither also sees great potential for the gamma lens in a two-lens array as a possible replacement for mammography, because of its ability to locate very small tumors without discomfort to the patient. A full-scale medical imaging lens was constructed and tested with a number of phantoms in Smither's research laboratory.

The researchers will next design and build a smaller lens to see if the resolution can be improved even more, continuing experiments with phantoms. They expect to test the array in clinical trials in two or three years.

Smither built the world's first gamma-ray lens-a 20-inch lens for use in an astrophysics telescope—10 years ago at Argonne. He also has built other gamma-ray lenses of various sizes and materials for use in cameras and telescopes, as well as developing optics for Argonne's Advanced Photon Source, which produces the nation's most brilliant X-rays for research.



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