Detector materials drive increased PET productivity

The U.S. market may soon welcome two new dedicated PET scanners under four different labels. The scanners, formally launched at the annual meeting of the Society of Nuclear Medicine in Toronto, are remarkable for the materials built into their detectors, as well as the cross labeling that one of these products may achieve.

Two unconventional detector materials promise improved patient throughput by increasing the count rate. Gadolinium oxyorthosilicate (GSO) has been built into the Allegro from Philips ADAC, and lutetium oxyorthosilicate (LSO) is the heart of the product built by CTI PET Systems and being readied for sale under private labels by Siemens Medical Solutions and CTI (as the Ecat Accel), as well as by Marconi Medical (as the L360).

The new PET system could appear under the Marconi label within three months, along with other PET scanners supplied by CTI (SCAN 5/23/01). Whether the acquisition of Marconi by Philips will affect that plan is not known, as this scanner would compete directly with Philips’ own Allegro, which will begin shipping in midsummer. Siemens has already begun routine delivery of Accel.

Expanding beyond Siemens’ distribution channels is part of a master plan for market dominance, according to Ron Nutt, senior vice president of CTI PET Systems, which is a joint venture between CTI (50.1%) and Siemens (49.9%). Rather than signing distribution partners, the company wants to supply the key components of dedicated PET systems: the detector, optoelectronics, and data acquisition channels.

“We control not just the material (LSO), but the fast electronic channels that are necessary to bring the data out,” Nutt said. “Just like PCs have Intel inside, we hope PET scanners will have CTI inside.”

How the newest products will improve productivity is a matter of speculation. LSO and GSO offer increased sensitivity compared with detectors using conventional materials such as bismuth germinate and sodium iodide. Along with improved electronics and processing technology, the new detector materials promise to cut scan times by up to 50%, according to corporate executives.

By switching to GSO, increasing the speed of the electronics, and tweaking positioning algorithms, ADAC was able to double the counts acquired in a typical scan on its Allegro, compared with its next fastest product, C-PET. The potential end result, according to Josh Gurewitz, senior director of nuclear medicine marketing at ADAC, is a 20- to 30-minute exam. These time savings are an estimate, because actual scan times vary depending on different imaging protocols.

“We need to standardize performance testing routines in PET as we have in nuclear medicine, so we can really compare these devices to each other,” Gurewitz said.

Within three years, however, such benchmarking may not be necessary, as scan times will have dropped to five minutes, according to Nutt. Driving this improvement will be advances in detectors, electronics, and processors. CTI PET Systems will be at the forefront of those advances, he said.

“Data corrections have to be very fast, and reconstruction speed has to increase dramatically,” Nutt said. “These things are challenging, but no additional breakthroughs are needed.”