How does FDA regulate CT Systems?
CT imaging systems are regulated by the FDA under two statutes. They are regulated as radiation-emitting electronic products under the Radiation Control for Health and Safety Act and as medical devices under the Medical Device Amendments to the Food, Drug, and Cosmetic Act. The regulations implemented under these laws place controls or requirements on the manufacturers of the CT systems rather than on the users of the CT systems.
The use of CT systems for medical purposes is controlled, in the U.S., largely at the State and Local government levels. States control the practice of medicine, license medical practitioners and typically license or register facilities operating medical x-ray systems such as CT systems. Some States have established regulations regarding the operation of screening programs that employ ionizing radiation.
Radiation Safety Standard
Under the Radiation Control for Health and Safety Act, CT imaging systems are subject to the equipment performance standard for diagnostic x-ray systems administered by the FDA . This standard:
For CT systems, the standard primarily establishes requirements for labeling and for providing product performance information. It does not establish patient radiation dose limits nor does it address the imaging performance or efficacy of CT systems.
Medical Device Controls
Through the Medical Device Amendments, FDA is responsible for assuring the safety and effectiveness of medical devices. Medical devices are classified into one of three classes, based on the risk associated with the device and controls needed to assure safety and effectiveness. CT imaging systems are Class II medical devices. This means they are subject to:
Manufacturers of CT imaging systems must submit premarket notifications (510(k)s) to FDA. In these notifications, they must demonstrate that each new CT system is "substantially equivalent" in terms of its characteristics, performance and safety to CT systems previously cleared or already on the market before the 1976 Medical Device Amendments.
No Screening Indication Approved
CT systems were manufactured and marketed for diagnostic use prior to
the 1976 Medical Device Amendments and were placed in Class II based on
the level of risk they present. These devices continue to be cleared for
marketing for general imaging purposes. No data have been presented to
the FDA to demonstrate that these devices are effective for screening,
i.e., testing individuals without symptoms. Before FDA would allow such
a claim or indication for use by the manufacturer, the manufacturer would
have to provide valid scientific data for such a new use by submitting
a premarket approval application for this new indication. This means that
manufacturers of CT imaging systems cannot make claims that the products
are intended to be used for screening non symptomatic individuals. Nevertheless,
individual physicians may decide that a patient without symptoms can benefit
from screening with CT even though data supporting such a use has not
been submitted to the agency. Such use of a medical device is referred
to as "off-label" use and is a judgment left to physicians.
However, statements that say or imply that FDA has approved CT scanning
for whole-body screening uses are not correct.
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