Digirad links with Stanford in solid-state gamma camera effort

Vendors scramble for next step in digital

The race to develop a solid-state digital gamma camera is heatingup. San Diego-based start-up Digirad is getting attention frommedical imaging vendors trying to keep pace with GE Medical Systemsand its effort to build a solid-state gamma camera.

Solid-state gamma cameras would replace the photomultipliertubes and scintillation crystals used in Anger-based systems,resulting in a truly digital gamma camera. GE got a leg up inits solid-state program earlier this year through a grant fromthe U.S.-Israel Science and Technology Commission (SCAN 2/15/95).GE has partnered with the eV Products division of II-VI Inc. towork on the detectors.

Another company developing a solid-state digital gamma camerais Digirad, formerly known as Aurora Technologies. The San Diegocompany has received several inquiries from GE's competitors aboutits technology, according to Richard Conwell, vice president ofbusiness development.

Digirad has transferred to the medical arena a gamma camerait developed to conduct defense-treaty verification of Sovietnuclear warheads, Conwell said. Digirad's technology uses cadmiumzinc telluride as a detector material and needs no photomultipliertubes or scintillation crystals.

"It will directly convert gamma rays to electrical pulses,"Conwell told SCAN.

In addition to image quality advantages conferred by goingdigital, Digirad's detectors will be lighter and less bulky thanconventional detectors, according to Conwell.

Digirad has linked with Stanford University to access readoutelectronics arrays developed at that institution. The arrays routethe signal coming from each pixel on the cadmium zinc telluridearray to the image processing computer. Digirad, the Departmentof Energy and the Stanford Linear Accelerator Center (SLAC) signeda cooperative research and development agreement (CRADA) lastyear to fund Digirad and SLAC's work on the detectors. SLAC willreceive $214,000 in DOE funds, while Digirad will fund its ownwork in parallel with SLAC's.

Digirad hopes to have a mock-up of the camera on display atthe Society of Nuclear Medicine meeting next month, with a work-in-progressprototype ready at this year's Radiological Society of North Americameeting. The company at present is developing the entire cameraitself but may partner with an existing gamma camera manufacturerto provide image processing computers and potentially sales anddistribution, according to Conwell.

"We have been approached by major camera suppliers andare in cooperative discussions with more than one," Conwellsaid. "As a result of (the GE) announcement, other companiesare calling us."

ADAC Laboratories of Milpitas, CA, is one nuclear medicinevendor that is watching the development of solid-state digitalgamma cameras, according to CEO David Lowe. The cost of solid-statedetectors must drop before the technology can be used in a commerciallyviable product, he said.

"We think it's going to be viable and we're followingit," Lowe said. "Our cost estimates at this point (indicate)that the cost of the detector is prohibitively expensive giventhe improvement in energy resolution and diagnostic accuracy.Just like anything else, we expect solid-state circuitry to comedown in cost, and when it does we hope to be there with appropriateproducts."