Medical devices; performance standards for dental and mammographic X-ray devices; amendment--FDA. Proposed rule

The Food and Drug Administration (FDA) is proposing to exempt panoramic dental x-ray units from the requirement that they be manufactured with exposure timers which automatically reset to zero upon premature termination of an exposure. Removing the automatic timer reset requirement will not compromise the quality of the radiographic image and will protect patients from being subjected to unnecessary radiation due to repeat radiographs. FDA also proposes five changes to align the performance standard with the equipment requirements issued under the Mammography Quality Standards Act of 1992 (MQSA). First, the agency proposes to remove any reference to the use of equipment not specifically designed for mammography from the performance requirements for mammography equipment. Second, FDA proposes that the mammographic field alignment requirements restrict the irradiation beam to less than 2 percent of the source-image receptor distance (SID) beyond the image receptor edges. Third, it is proposed that the definition of an image receptor support device be amended to specify that it must provide a primary protective barrier for any orientation of the x-ray tube and image receptor support device assembly. Fourth, it is proposed that the useful beam must be confined to the dimensions of the primary barrier provided by the image receptor support device (except on the chest wall side). Fifth, it is proposed that exposures not be permitted without the primary barrier in place.