Physicist Bob Smither developed a gamma-ray lens for use in cancer detection that is so precise it can detect tumors as small as a grain of rice. Smither hopes this technology will replace mammography since it can locate tiny tumors without patient discomfort.

Gamma-ray lens detects rice-sized tumors

A new approach to cancer detection uses a copper crystal lens to help researchers find tumors no larger than a grain of rice.

The technology 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 gamma radiation emitted from a small radioactive source in the body of a patient into a small, well-shielded detector.

Researchers placed a small radioactive source in a “phantom”—an acrylic plastic device designed to simulate areas of the human body—and scanned it with the lens. The technology can pick up mildly radioactive tracers as small as a dill seed.

“The key is sensitivity and spatial resolution,” says developer Bob Smither. In addition to detecting small tumors, the technology can also pinpoint their location within a millimeter or two.

Today, most cancers are 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. No additional radiopharmaceutical would be needed. 

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 causing patient discomfort. A full-scale medical imaging lens was constructed and tested successfully with a number of phantoms in Smither’s laboratory.

The researchers will next design and build a smaller lens to see if the resolution can be improved. 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 developed optics for the Advanced Photon Source and built gamma-ray lenses of various sizes and materials for use in cameras and telescopes.

For more information, please contact Catherine Foster.

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