FAQ: Radiation Risk From Medical Imaging
What You Need to Know About Radiation Risks From CT, Other Scans
What are the risks of medical imaging procedures?
Even when done properly, medical imaging procedures can damage DNA and
increase a person's lifetime risk of cancer.
In the U.S., a person has a one-in-five lifetime risk of cancer. Imaging can
increase this risk.
For example, a 2009 study estimates that a CT coronary angiography given at
age 40 will cause cancer in one in 270 women and in one in 600 men. The risk is
about twice as high for a CT scan given at age 20 and about half as high for a
CT scan given at age 60.
But scans aren't always given properly. Without taking the right
precautions, a patient may be exposed to too much radiation, thereby increasing
the risk without increasing the benefit.
Lack of standardization compounds the problem. For example, another 2009
study found that in the San Francisco Bay area alone, the dose of radiation
given in the same kind of CT scan varied 13-fold between the highest and lowest
dose given by different hospitals.
Moreover, doctors may prescribe scans that aren't medically justified. And
since risk from radiation exposure accumulates over a lifetime, certain scans
may not be appropriate for people who've already had a lot of scans.
Cancer isn't the only risk. Accidental exposures to high doses of radiation
hair loss. Cataracts can develop in
eyes directly exposed to radiation.
What is the FDA doing to reduce the risks of medical imaging?
The FDA's basic plan is twofold: make sure that every scan is medically
justified and optimize the radiation dose a patient gets in each procedure.
To accomplish this, the FDA is launching three initiatives.
The first initiative will require the makers of CT and fluoroscope devices
to incorporate safeguards into the design of their machines and to provide
better training. Ideas include:
- Requiring the devices to display, record, and report settings and radiation
- Requiring the devices to alert users when the radiation dose exceeds the
optimal dose for most patients
- Enhanced training and certification of device users
The second initiative will focus on giving doctors the tools they need to
use medical imaging more wisely. Ideas include:
- Requiring devices to transmit radiation dose information both to the
patient's medical record and to a national dose registry.
- Establishing nationally recognized standard radiation levels for each
imaging procedure -- including a separate standard for children.
The third initiative will focus on empowering patients. Ideas include:
- Giving patients a "medical imaging record card" to track their radiation
exposure from scans.
- Providing a tool on the FDA web site that will allow patients to track
their own medical imaging history and to share it with their doctors.