The U.S. Food and Drug Administration announced this week that it will set new safeguards for medical imaging to reduce the amount of radiation to which patients may be exposed through increasingly common radiation-based diagnostic procedures.

Like all medical procedures, computed tomography (CT), fluoroscopy, and nuclear medicine imaging exams present both benefits and risks. These types of imaging procedures have led to improvements in the diagnosis and treatment of numerous medical conditions. At the same time, these types of exams expose patients to ionizing radiation, which may elevate a person’s lifetime risk of developing cancer.

Through the Initiative to Reduce Unnecessary Radiation Exposure from Medical Imaging, FDA is advocating the universal adoption of two principles of radiation protection: appropriate justification for ordering each procedure, and careful optimization of the radiation dose used during each procedure. In other words, each patient should get the right imaging exam, at the right time, with the right radiation dose.

According to a March 2009 report by the National Council on Radiation Protection and Measurements (NCRP), the U.S. population’s total exposure to ionizing radiation has nearly doubled over the past two decades. This rise is largely attributable to increased exposure from CT, nuclear medicine, and interventional fluoroscopy. NCRP estimates that 67 million CT scans, 18 million nuclear medicine procedures, and 17 million interventional fluoroscopy procedures, and 18 million nuclear medicine procedures were performed in the U.S. in 2006.

Concerns have been raised about the risks associated with patients’ exposure to radiation from medical imaging. Because ionizing radiation can cause damage to DNA, exposure can increase a person’s lifetime risk of developing cancer. Although the risk to an individual from a single exam may not itself be large, millions of exams are performed each year, making radiation exposure from medical imaging an important public health issue. Some experts have estimated recently that t approximately 29,000 future cancers could be related to CT scans performed in the U.S. in 2007. While estimates vary, most responsible public health officials agree that care should be taken to weigh the medical necessity of a given level of radiation exposure against the risks.

Against this backdrop, plaintiff lawyers continue to seek medical monitoring in the form of CT and other scans for millions of proposed class members around the country.  Plaintiffs’ theory is that exposure to an alleged toxic substance has put the class at an increased risk of developing disease in the future, and thus they need medical monitoring to early detect the disease.  Most jurisdictions have not recognized this claim, but in those that do, defendants will want to pay close attention to the elements of the claim that require a plaintiff to prove that the testing is reasonably medically necessary or part of the standard of care.  The reason that treating physicians and public health agencies do NOT recommend monitoring in the form of CT scans for healthy, asymptomatic folks may increasingly include this issue of potential over-exposure.  While jurors may come to the court room with the pre-load that monitoring is great because early detection saves lives, the reality is that in many contexts, monitoring may do more harm than good.

Because CT, fluoroscopy, and nuclear medicine require the use of radiation, some level of radiation exposure is inherent in these types of procedures. Only when these procedures are conducted appropriately do the medical benefits they can provide generally outweigh the risks.  In the medical monitoring context, patients may be exposed to radiation without sufficient clinical need or benefit. Unnecessary radiation exposure, and thus cancer risk, results from the performance of a particular medical imaging procedure when it is not medically justified given a patient’s signs and symptoms, or when an alternative might be preferable given a patient’s lifetime history of radiation exposure.  That kind of needed individual assessment is one of the reasons why class-wide determination of medical monitoring is a bad idea. While plaintiffs trumpet the new technology, reports suggest that the radiation dose associated with one CT abdomen scan is the same as the dose from about 400 chest X-rays.