Hologic of Bedford, MA has announced that the FDA’s Radiological Devices Panel will be reviewing the company’s Selenia Dimensions 3-D digital mammography tomosynthesis system. The device takes many low energy X-ray shots from different angles and reconstructs a 3D image of the breast. Hologic’s Selenia Dimensions technology is already available in most of the rest of the world, but FDA’s regulatory bureaucracy will only meet to discuss the system in September.
Some details about breast tomosynthesis from a Hologic white paper:
The breast is compressed in a standard way. While holding the breast stationary, the x-ray tube is rotated over a limited angular range. A series of low dose exposures are made every degree or so, creating a series of digital images. Typically, the tube is rotated through 10-20 degrees and 10-20 exposures are made every 1° or so during a total scan of 5 seconds or less. The individual images are projections through the breast at different angles and these are what are reconstructed into slices.
Normally the breast would be placed in the MLO or the CC view, although the tomosynthesis system should support
the ability to acquire images in any desired orientation. One consideration in the design of tomosynthesis systems
is the motion of the x-ray source during acquisition. The x-ray tube can move in a continuous or step-and-shoot motion. With continuous motion x-ray exposures must be short enough to avoid image blurring due to focal spot motion. If step-and-shoot motion is employed, the gantry must come to a complete stop at each angular location before turning on the x-rays, otherwise vibration will blur the image. The most important criteria is that the total scan time be as short as possible, to reduce the possibility of patient motion which will degrade the visibility of small microcalciï¬cations and small spiculations.