Firm unveils digital detectors at RSNA show

Nuclear medicine vendor Sopha Medical showed its hand in expandingthe functionality of its line of gamma cameras at this month'smeeting of the Radiological Society of North America. Sopha, ofColumbia, MD, displayed works-in-progress developments in digitaldetector design and non-uniform attenuation correction.

Sopha claims that the specifications for its version of digitalmeet or exceed those of its competitors, including arch-rivalADAC Medical Systems. ADAC introduced its Epic line of digitaldetectors at the RSNA meeting (SCAN 12/14/94). Sopha describesits technology as an enhanced Anger method that was designed tobring cost-effective digital to its installed base. Sopha's versionof digital will complement that of Summit Nuclear, a manufacturerof digital gamma cameras with whom Sopha signed a merger agreementlast week (see story, page 1).

Sopha's digital detectors will retrofit to the vendor's entireline of gamma cameras. It employs five flash analog-to-digitalconverters, positioned after the photomultiplier tube stage anddesigned to capture the five parameters that govern scintillationevent location and energy. The converters sample continuouslyat a rate of 100 nanoseconds and use a patented deconvolutionsampling process that makes the digitized signals more discreteand easier to resolve. Digital linearity energy and uniformityare performed on a single application-specific integrated circuit(ASIC).

Going digital will boost the count rate on the vendor's gammacameras to 400,000 counts per second in the 20% energy window,according to Lonnie Mixon, director of sales support. Digitaldetectors also enable Sopha's cameras to image up to four isotopesat once. In addition, Sopha's digital detectors will be retrofittableto the vendor's cameras in the field, which is not possible withEpic. Sopha hopes to be delivering digital detectors in mid-1995with a list price of about $20,000 as an option on a new camera.

Sopha's simultaneous transmission-emission attenuation correctionprotocol is being developed for Sopha's flagship Sophycamera DSTas well as DST-XL, a whole-body adjustable-angle camera that madeits RSNA debut at this year's meeting (SCAN 11/23/94).

Sopha's attenuation correction design features scanning linesources mounted opposite each detector head when they are configuredin the 90º position. The line sources can be folded awayfrom the camera heads when not needed to preserve the camera'sopen-gantry design and allow access to the patient. Sopha hopesto begin shipping the product in mid-1995. Like ADAC, Sopha willbe able to offer digital detectors and attenuation correctionon its products.