Sectra invests in low-dose detector for mammography screening

Digital system tries to crack European market

Swedish IT and medical technology company Sectra is increasing its stake in the digital mammography market. Sectra is investing $11.6 million into Stockholm-based Mamea Imaging, developer of the novel detector technology and ergonomic imaging stand that make up Sectra's low-dose digital mammography system.

The detector, whose design has been patented by Mamea, is the fundamental building block for Sectra's MicroDose mammography imaging system. The crystalline silicon detector exploits photon-counting technology to record the level of x-ray radiation penetrating the breast tissue. The technology is similar to that invented by physicists working at the CERN particle accelerator in Geneva. The method was subsequently refined for medical imaging by researchers at the Royal Institute of Technology in Stockholm.

Sectra's investment took the form of convertible debentures, which can be converted into shares at any time until their maturity on July 1, 2008. Conversion would boost Sectra's existing ownership of Mamea from 38% to 75%, paving the way for the smaller company to join the Sectra Group as a subsidiary.

Although the two Scandinavian companies have a good working relationship, the deal places future supply of Sectra's MicroDose mammography imaging units on a firmer footing, according to Henrik Mansfeld, business area manager for Sectra Imtec.

Photon counting is much more efficient than existing digital detector technologies used in medical imaging, he said. Some competing digital radiography and mammography products combine a cesium iodide scintillator with either an amorphous silicon detector or CCD for indirect conversion of x-rays to digital data. Others rely on amorphous selenium detectors to convert x-rays directly into electrical charges that are then converted into digital images.

"Rather than converting the information over different steps, such as light conversion or charge collection, we just count the x-rays one by one," Mansfeld said. "This is actually the information you are looking for."

Sectra claims its crystalline silicon detector captures 95% of transmitted x-ray photons, compared with the 50% detected by conventional film-based systems. Scattered radiation is also minimized, eliminating the need for a bucky grid. The improved efficiency, combined with the photon counting, allows MicroDose mammography units to operate at a fifth of the dose of conventional film-based systems, he said.

"We see this as an opportunity to make a good diagnostic examination better by reducing the dose," Mansfield said. "If you can save dose, then why would you not? This is a competitive argument for many breast centers that are screening healthy women, at regular intervals, over a number of years."

The low-dose breast imaging units are being sold in Europe in combination with Sectra's PACS. Hospitals and breast clinics purchasing a MicroDose mammography system are consequently buying a complete digital mammography solution, according to Mansfeld.

"With the PACS, you can facilitate the workflow and throughput required for screening mammography, as well as clinical needs," he said. "You can look at any DICOM images at the same workstation and also images from different digital mammography modalities."

Sectra installed its first MicroDose mammography system at Helsingborg Hospital's Breast Disease Center in Sweden during early September 2003. The dedicated women's health center provides diagnostic breast imaging exams for about 14,000 patients annually. More than 1500 women underwent mammography with the full-field digital unit during the first two months of its clinical operation. Since then, the system has been used to examine an average of 60 women per day.

"I would not be surprised if the Helsingborg Breast Disease Center has set a new world record in examinations using a single, digital full-field mammography system," said Dr. Torbjorn Kronander, president of Sectra Imtec. "I am impressed by the throughput capacity."

A second MicroDose mammography system is scheduled for installation at the Klinikum Krefeld in Germany. Meanwhile, Sectra is taking steps to secure approval for its low-dose system to be marketed to U.S. breast imaging centers.

"The clinical trial we need to complete for the FDA approval process will start early in 2004," Mansfeld said.

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