Although tremendous advances have been made in protecting radiologists and technologists from the hazards of radiation exposure, the danger continues to be very real and requires vigilance.

Radiologists were much more likely than other medical specialists to develop cancer in the early part of the 20th century. British radiologists entering the field before 1921 had a 75% higher cancer rate than other physicians, according to John “Fritz” Angle, MD, associate professor of radiology at the University of Virginia, Charlottesville, in an address at the 2004 meeting of the Society of Interventional Radiology (SIR). Today, the cancer rate for radiologists and technologists is no different than that of the general population, thanks in part to a better understanding of the effects of radiation. 1 By following proven safety procedures and monitoring exposure, technologists and radiologists can minimize or avoid exposure altogether.

One of the reasons that cancer rates have declined and the safety of both medical professional and patient has increased is because the exposure guidelines fell continuously throughout the 20th century. It was not until around 1920 in the United Kingdom that radiation exposure could even be measured, and the initial safe doses were much higher than the current 5 rem per year limit. “The first dose limits were set by how much it took to visibly change someone’s skin in a short period of time, [which is] a huge dose,” says Angle.

The danger of exposure to ionizing radiation is its effect on cellular structure. “Radiation can knock an electron out of its orbit around an atom and produce an ion,” says Richard Morin, PhD, Brooks-Holleran professor at the Mayo Clinic, Jacksonville, Fla. “If that electron is part of a chemical bond–in a strand of DNA, for instance–and is knocked out, then, in fact, that chemical bond does not exist any more and that may change the nature of that molecule.” Radiation damage is cumulative.

The limits, which are issued by physicists associated with the Nuclear Regulatory Commission (NRC), are continuously reviewed and historically have been lowered every 10 years, though Angle notes it has remained constant over the last decade.

In addition to the lower limits, careful monitoring of radiation exposure with radiation badges and room monitors has also helped to ensure that patients and personnel are receiving lower radiation exposure.

Though most modalities carry minimal risk of exposure, fluoroscopy and CT can be considered high risk to both the operators and patients.

Whatever the risk, there are several ways radiology departments can control and limit exposure.


Badges and monitors are simply the means to measure exposure, not to limit it. Departments that want to limit the amount of radiation exposure need to follow the three basic principles of radiation safety:

  1. maximize distance,
  2. minimize time of exposure, and
  3. increase shielding.

“If all those things are done, then it’s reasonable to expect that the people who are performing these procedures will not have significantly higher exposures than any other part of the health care team,” says Morin.

In the examination room, the biggest radiation risk is not the beam, but the patient. “For the people in the room, the biggest source of radiation is the scattered radiation from the patient’s body,” says P. Andrew Karam, PhD, research assistant professor in the Department of Biology at Rochester Institute of Technology, Rochester, NY. “In general, we assume the scattered dose is about 1% of the dose of the primary beam.”

Even with the danger posed by scatter, the likelihood of serious injury is low, says Morin. “The reason for that is [primarily because] radiology is supervised in one way or another,” he says. “That means there are a large number of things that are done to keep the radiation exposure to the staff as low as reasonably achievable.” The guidelines for handling radioactive materials come from the state or federal government. There are no national guidelines governing the use of radiological equipment.

Safety guidelines are monitored and enforced by a radiation safety officer (RSO), who is typically either a physician or physicist. For instance, the RSO determines where personnel should wear their radiation badge.

By observing regulations, monitoring radiation exposure with radiation badges, and following the three cardinal exposure rules, most physicians and technologists receive no more than typical background radiation exposure. According to Karam, those who receive the highest radiation dosages are interventional radiologists at 1 to 2 rems of radiation per year, far lower than the 5 rem upper limit sanctioned by the NRC, which he describes as very conservative. Typically, radiologists and technologists receive about 100 to 200 millirads of radiation exposure a year. Typical background radiation exposure is about 1 millirad a day.

Even though the regulations and principles are in place to protect both patients and operators, Karam, who was an RSO for 5 years at the University of Rochester and Strong Memorial Hospital, Rochester, NY, notes that staff sometimes balks at having to follow them, particularly the annual, legally required refresher courses. “The biggest argument I would get from our physicians was along the lines that this is stupid, I’m too busy to have to deal with this,” he says. “But then I have to point out that if they do not participate, they’re not going to be qualified as radiation workers and they won’t be in the position to save any lives.”

With all these rules, procedures, and equipment in place, injuries to radiologists, technologists, and patients are rare. But they do occur, particularly to one subspecialty group–interventional radiologists–on a more regular basis.


Like other subspecialties, interventional radiology can be low-risk. But, because of the location of the radiologist in regard to the patient during the procedure, interventional radiology violates the time-distance-shielding troika, making it potentially more dangerous to the radiologist than other specialties. Angle, himself an interventional radiologist at the University of Virginia Medical Center, explains that radiation exposure, particularly of the hands, is a result of a number of factors, some avoidable, some not. “There’s almost always a way to avoid directly exposing the hands,” he says. “Sometimes it does become an absolutely necessary part of the procedure. We run a risk when we do that, and rarely do we choose to do that.”

Radiation exposure can have a number of short-term and long-term effects for radiologists, ranging from skin damage to hair loss to cataracts to cancer.

Angle says that the University of Virginia Medical Center does a good job monitoring radiation exposure, regularly collecting the radiation badges and sending yearly reports about the amount of radiation exposure to the radiologists or technologists.

When an overexposure to a radiologist or technologist does occur, the patient can also be injured as well, setting in motion an investigation by the RSO to determine whether the injury was unavoidable. “The requirement we had at Strong was that any time there was a radiation injury to the patient, then radiation safety had to be informed,” says Karam. “We had to do a dose estimate, we would go through all the exposure records to try to recreate what the dose was, and try to figure out what happened and keep it from happening again. The level of dose that it takes to hurt a patient or get skin burns is on the level of a couple hundred rem to the skin.” In the 5 years he was an RSO, Karam had to conduct only two investigations involving radiation burns of patients.

Nonetheless, changes in the field of radiology are raising new risks.

Angle explains that one factor contributing to the risk of increased dose to both patients and radiology staff is the fact that larger patients are being regularly imaged. “You need more x-rays to image through them, and you get more scatter. So the operator gets more exposure,” he says. “If you do more complex procedures with bigger patients, you’ve got things working against you that are raising your potential exposure. And you’ve got to do things to compensate for that.” He recommends increasing shielding–particularly for the interventional radiologist–limiting the dose rates, and better training as ways to better protect the operator.

New pulse fluoroscopy and measurement technology could help solve some of the emerging imaging risks. “The newer fluoroscope rooms have dose-saving features, which is important,” says Angle. “I don’t think anyone should do interventional procedures on a regular basis unless they have those rooms that have been out in the last few years with the dose-saving features. All the newest rooms have dose meters, so you can see this is what the patient is getting nowthis is the dose rate. [You can see] how quickly they’re accumulating radiation, and what their total accumulated dose for that procedure is. We record that for every case, and I think everyone needs to get a room with that capability.”

Morin, who sits on the Board of Chancellors of the American College of Radiology (ACR) and is chair of its Commission on Medical Physics, says that the ACR is involved in educating lawmakers about the various risks involved with self-referral of imaging studies. “There are a very large number of [concerns such as] overutilization, which is a major issue,” he says. “There is a component of overutilization that is of concern to those in the radiation protection community.”

The real danger to medical staff does not lie in the radiology department but outside it. “In most states you actually don’t have any training in order to run a fluoroscope,” says Morin. “All you have to do is have a degree in the healing arts–an MD or a DO. That sort of thing is a bigger worry from a radiation protection standpoint. Unlike radiology offices where all of the units are seen and are well calibrated and exposures are measured by the physics consultant, that’s not always true in some of these other physicians’ offices. The other thing, which is a bigger concern in the hospital setting, is people using fluoroscopy for localization purposes. Very few of the states require any certified training of those individuals.”

Radiology has come a long way from its early–risky–days, emerging as a safe and well-respected medical specialty. But safety is never guaranteed, which means that departments and their RSOs must remain vigilant that radiologists and technologists have good radiation hygiene and monitor their radiation exposure.

Chris Wolski is a contributing writer for Decisions in Axis Imaging News.


  1. Yoshinaga S, Mabuchi K, Sigurdson AJ, Doody MM, Ron E. Cancer Risks among Radiologists and Radiologic Technologists: Review of Epidemiologic Studies. Radiology. 2004 Sep 16 [Epub ahead of print].