Emerging
medical imaging technologies being developed for the terahertz spectrum may
face regulatory hurdles from an unexpected Federal agency: the Federal
Communications Commission (FCC). While the Food and Drug Administration (FDA)
has jurisdiction over medical devices with respect to safety and effectiveness
– including premarket approval, inspection of manufacturing facilities, and
monitoring of post-market adverse events – the FCC has jurisdiction over
certain technical and spectrum use requirements for medical devices that
operate on radiofrequency (RF) spectrum. Medical device developers need to be
aware of the current state of play at the FCC in these areas.
Terahertz Imaging
Medical imaging
technologies can operate on a variety of frequency bands. In the terahertz
frequency range, the waves are extremely short, smaller than the size of a
cell. When these radio waves are sent through tissue, the signal passes through
the tissue and creates “scattering.” (Atoms are “shaken,” but not broken or
destroyed.) Imaging in the terahertz frequencies can reveal what is occurring
at the cellular level, providing the ability to distinguish between cells that
have cancer or not, for example, or between different types of cells such as
fatty tissue or liver tissue. Obviously, these are promising diagnostic methods
that could enhance the detection and treatment of pathological conditions, such
as skin cancer.
The Basics
of FCC Regulation of Medical Devices
The FCC regulates
several aspects of wireless medical devices. These include: 1) issuing test
licenses to designers and manufacturers to test devices prior to approval; 2)
issuing grants of equipment authorizations, or otherwise providing mechanisms
for allowing device use; 3) setting out rules for the use of frequencies
designated for medical devices; 4) establishing new frequencies for use by
wireless medical devices; and 5) imposing requirements for ascertaining and
complying with limits on human exposure to RF energy.
The spectrum
managed by the FCC is commonly used for communications, such as cellphones,
Wi-Fi and radio, with FCC currently regulating the frequency range from 3 kHz
to 3000 GHz. (Frequency refers to the wavelength of the radio waves passing
through the air. Radio waves can range in size from 100 meters at the lower
frequencies to decimillimeters at the highest frequencies. The size of the
radio wave determines the use of a frequency range.) Terahertz spectrum falls
at the top end of the regulated frequency range, just below light waves on the
electromagnetic spectrum – specifically, 300-3000 GHz.
The FCC
Provides for Only Limited Operations on Terahertz Spectrum
The FCC does not
have service rules in place to allow for operations in the terahertz bands. In
fact, FCC presently only has service rules (i.e., rules for use) up to 95 GHz,
and only has spectrum allocated (i.e., planned out for use) up to 275 GHz.
Because spectrum is a finite resource, the FCC must plan its use to ensure that
multiple users can co-exist.
The FCC currently
has an open rulemaking proceeding that proposes to establish new rules for
operations beyond the 95 GHz range, but only up to 275 GHz (just below the
terahertz range). The only proposal that the FCC has made thus far with regard
to use of the terahertz range is to provide for testing licenses in that range,
with the possibility of allowing very limited sales of new technologies.
Absent service
rules, medical imaging devices operating in the terahertz frequencies may only
be marketed if they can be categorized as “Industrial Scientific and Medical
(ISM)” equipment. And even then, the FCC employs a “case-by-case” evaluation of
each device, which means that designers and manufacturers cannot design to specific
technical rules, but instead must wait until the FCC evaluates their product
before knowing whether they will receive FCC authority to market the device.
This process obviously creates a good deal of regulatory uncertainty. Moreover,
it does not apply to devices that have a communications function, such as
Bluetooth or Wi-Fi used to send data collected by the device to a smartphone or
router.
Europe and Japan are both ahead of the U.S.
