Sopha SPECT takes different angle

Cardiac SPECT studies usually involve 180´ anterior detectorrotation, rather than a complete circling of the patient, becausethe spine blocks much of the posterior emissions. For this reason,three-headed SPECT systems and opposing-detector, dual-head camerasare not optimized for cardiac work, said Randy Weatherhead, vicepresident of marketing for Sopha Medical Systems.

SMS of Columbia, MD, is the U.S. subsidiary of Sopha Medicalin France.

Sopha has developed a patent-pending, variable-angle detectorsystem that allows users of its dual-head Sophycamera DST systemto shift from an opposing-detector alignment for whole-body andbrain scans to a cardiac-optimized configuration.

The two detectors can be angled perpendicular to each otherabove the body so they have to move only 60´ to cover the180´ span of emissions from the heart. This is a third moreefficient than a triple-head camera, he said.

The inner angles formed by the triangulation of three detectorsin a SPECT camera must be 120´, given the geometry of thesystem. This requires two of the detectors to move farther inorder to take in the 180´ of anterior emissions, while thethird detector idles in the posterior position, he said.

"We wanted to have our cake and eat it, too--to performbrain and body scans using two heads in normal alignment but havethe capability to move the heads into the optimized cardiac position,"Weatherhead said.

Sopha is applying for three patents on the DST camera. Thesepatents cover:

• the variable-angle detector design;

• a 90´ swivel capability that places the widerdimension of the detector lengthwise; and

• a system of independent micromotors on the two heads,which allows for asynchronous detector movement.

The swivel feature can provide a larger field-of-view thanjumbo detectors when imaging narrow patients, such as in pediatricbone scans. Asynchronous detector movement enables the dual-headsystem to perform body contouring studies in planar whole-bodyand SPECT applications.

Although dual-head SPECT systems were shown at last year'sSociety of Nuclear Medicine meeting, shipments are just beginning.Statistics from the National Electrical Manufacturers Associationshowed no actual deliveries of dual-head systems this year throughApril. Sopha only recently shipped its first DSX Bodytrak system,which was introduced last year, Weatherhead acknowledged.

Sopha will continue to sell the fixed-detector, dual-head DSX,since its jumbo detectors make the camera more efficient for dedicatedbody work, he said.

However, cardiac imaging is gaining in importance in nuclearmedicine with the introduction of technetium heart agents.

"The primary reason to buy a SPECT camera today is todo cardiac SPECT," he said.