Elscint's twofer CT breaks ground

Elscint introduced a unique CT design concept at the DecemberRadiological Society of North America show. The Israeli medicalimaging firm showed its premium CT Twin scanner as a works-in-progress.A Food and Drug Administration 510(k) application is under way.

The CT Twin uses slip-ring technology and high-speed opticaldata links developed for the Apex Helix, a sister product in nuclearmedicine. Elscint introduced the volumetric nuclear camera atthe 1991 Society of Nuclear Medicine show and displayed it againat the RSNA exhibit (SCAN 7/3/91).

While Elscint's application of continuous rotation scanningtechniques in nuclear medicine was an industry first, this wasnot the case in CT. What makes the Elscint CT Twin unique is notits continuous rotation but another, more radical acquisitionconcept: two solid-state detector arrays in the scanner acquireeither two slices or two spiral scans simultaneously.

The CT Twin acquires twice as much information in a singletime period as most fast CT scanners. This results in both improvedimage slices and dynamic scanning, which is particularly helpfulin contrast imaging, said Jerome S. Arenson, product manager.

"The geometry of the detectors is such that you get thedual slices," Arenson told SCAN. "The trick is to keepthe slices contiguous with zero intergap."

Because there is no gap between the two slices and they areacquired at exactly the same time, they can be merged into a singleslice that combines the motion artifact reduction of thin sliceswith thick-slice contrast, he said.

Elscint's scanner acquires slices in a cycle time of six seconds.Since two slices are taken at once, however, the actual acquisitiontime per slice is three seconds, Arenson said.

CT Twin acquires two 10-mm slices in each cycle during spiralscanning. This enables the system to scan 60 cm along the lengthof a patient in 30 seconds--about twice as fast as most spiralCT systems, he said.

Although the unit will sell for a premium CT price, it doeshave economic advantages, the most obvious being increased patientthroughput. Another fringe benefit of dual-image acquisition isthat the CT tube wears out more slowly, since one exposure resultsin two images, Arenson said.