In 2002, the American Society for Therapeutic Radiology and Oncology formed a radiological terrorism task force intended to help members cope with crises. The American College of Radiology (ACR) also decided to create a disaster task force. Arl Van Moore, MD, is chair of the ACR task force, which has established a web site1 publishing the primer for disaster preparedness in radiology. He has stated that the task force is designed to deal with the issues on which radiology professionals are experts: counseling people in radiation situations and coping with radiation incidents.2 The American Medical Association's disaster preparedness site was available first, but it has concentrated on the possible effects of biological and chemical terrorist acts. "There was a unique void related to nuclear terrorism or radiation devices that might be exploded in various areas: the so-called dirty bomb,"2 Van Moore has noted.

The multidisciplinary task force includes physicists, radiologists, radiation oncologists, industry representatives experienced in decontamination, and medical personnel from the armed forces. This large amount of collective experience will help the group educate professionals who will, in turn, serve as information resources for their hospitals and communities.

The task force plans to establish educational programs that will enhance the ability of radiologists, medical physicists, and radiation oncologists to respond to a radiation disaster effectively. Helping members of the radiology community act as sources of accurate information is a primary goal of the task force. Patients would naturally be among the recipients of this information, but so would news media, along with physicians engaged in planning appropriate responses to radiation disasters. Radiology workers are also encouraged to learn how to establish effective disaster-response programs within their own communities.

DISASTER PROBABILITY

In March 2002, the Federation of American Scientists (FAS) presented a study3 concerning the immediate and long-term consequences of the explosion of a dirty bomb (a conventional explosive combined with a radiation source) to the Senate Foreign Relations Committee. The report stated, "Radiological attacks constitute a credible threat. Radioactive materials that could be used for such attacks are stored in thousands of facilities around the [United States], many of which may not be adequately protected against theft by determined terrorists. Some of this material could be easily dispersed in urban areas by using conventional explosives or by other methods. While radiological attacks would result in some deaths, they would not result in the hundreds of thousands of fatalities that could be caused by a crude nuclear weapon. Attacks could contaminate large urban areas with radiation levels that exceed [US Environmental Protection Agency (EPA)] health and toxic material guidelines." The report continued, "Materials that could easily be lost or stolen from US research institutions and commercial sites could contaminate tens of city blocks at a level that would require prompt evacuation and create terror in large communities even if radiation casualties were low. Areas as large as tens of square miles could be contaminated at levels that exceed recommended civilian exposure limits. Since there are often no effective ways to decontaminate buildings that have been exposed at these levels, demolition may be the only practical solution. If such an event were to take place in a city like New York, it would result in losses of potentially trillions of dollars."3

Figure 1. Area affected by explosion of a cesium gauge in Washington, DC. Adapted from Hearings Before the Senate Committee on Foreign Relations.3

The eventual deployment of a radiation dispersal device by a terrorist organization is not particularly unlikely. The expertise needed is available from many sources, and the necessary materials are neither prohibitively expensive nor particularly well guarded. For example, while the United Nations International Atomic Energy Agency (IAEA) has accounted for most of the 10 kg of low-grade uranium looted from Tuwaitha, Iraq, site of the country's primary nuclear research complex, hundreds of containers of nuclear material were removed from Tuwaitha and at least six other Iraqi nuclear facilities. Most have been recovered, and the IAEA is reportedly unconcerned about the rest of the lost material's potential use in constructing a conventional nuclear weapon because it is not of the proper type or quantity.4 Occupation authorities, however, have not permitted the agency to check Tuwaitha's approximately 400 cesium 137 and cobalt 60 sources, which could be used in dirty bombs. Villagers in the area, particularly children, are said to exhibit symptoms of radiation sickness (which is more likely to be caused by cesium 137 and cobalt 60 than by low-grade uranium).

In June 2003, a man in Bangkok, Thailand, asked $240,000 for what he claimed was uranium. He was arrested by Thai police in a sting operation involving US investigators and found to have 30 kg of cesium 137 for sale.5

COMMUNITY PREPAREDNESS

When a dirty bomb explodes, the individuals who deal with the consequences will be local residents. National programs will provide as much help as they can, but patient care and site cleanup will be performed by those in the area. While people living outside major metropolitan districts might consider themselves safe because they reside far from iconic targets, they should be prepared because dirty bombs can go off unexpectedly in transit to their intended destinations. Safety cannot be assumed based on locale.

Of course, a terrorist's goal in setting off a dirty bomb would probably not be to increase long-term cancer rates; instead, the intent is more likely to be the creation of fear and hysteria in a large population. As the FAS presentation3 pointed out, a dirty bomb requires only a radiation source and some common explosives. In one scenario, the cesium gauge that was actually found in a North Carolina scrap-metal plant in 2002 would be exploded, using about 5 kg of dynamite, at the National Gallery of Art (Washington, DC). Residents of an area encompassing five city blocks would have an increased cancer incidence of one case per 1,000 people. An area of 40 city blocks, about a mile long, would exceed the contamination limits of the EPA, and its residents would experience one additional cancer case per 10,000 people. Decontamination (which often requires the demolition and removal of a structure) would be required in an area that includes the Capitol, Supreme Court, and Library of Congress (Figure 1).

A second scenario involves the explosion in Battery Park (Manhattan) of a bomb containing a cobalt pencil of the type used in food irradiation. Even if the prevailing winds were negligible, the contaminated area would extend as far as Danbury, Conn, and cleanup costs could exceed $2 trillion (1012).

James Smith, PhD, assistant director for radiation at the Centers for Disease Control and Prevention (CDC), has emphasized the importance of planning at the community level. He said, "In most mass casualty incidents, people will most likely go directly to their closest, most familiar hospitals. Most of them will be ambulatory or minimally injured, or the worried well."2 He continued, "This could contribute to a flood of people coming just for advice." The CDC, as a result of this probability, strongly recommends the establishment of secondary assessment centers at easily accessible sites such as athletic fields and community centers. "This is a basic step in protecting the hospital from being overrun,"2 Smith said.

RADIOLOGY'S CONTRIBUTION

An important role for radiology professionals in both hospital emergency departments and secondary assessment centers will be to ensure that no patients are refused treatment due to fear of radiation contamination. Medical personnel outside radiology may need to be reminded that as much as 90% of contamination can be eliminated by removing the patient's clothing; Smith said that universal precautions such as gloves, masks, and gowns would then generally be sufficient in preventing staff contamination. Hospitals should address this issue during disaster planning at the community level so that misinformed staff or large numbers of worried well can be prevented from adding to the problems encountered following a radiation disaster.

Robert Ricks, PhD, is director of the Radiation Emergency Assistance Center Training Site of the Oak Ridge Institute for Science and Education, Oak Ridge, Tenn. He has stressed the importance of an evidence-based approach in planning radiology's response to terrorism associated with radiation events. He has also responded to more than 1,000 radiation accidents over a period of 30 years. Based on this experience, he said, it is important to impress upon health care providers "that serious radiation emergencies with significant medical consequences and/or fatal outcomes have, over the past 20 years, involved members of the general public who had no idea that they are involved in such an event. The reason for this is that there is no unique disease associated with radiation exposure."2 Even lethal exposures can unfold over an extended period, so nuclear terrorism might not be perceived for some time unless the perpetrator announces the presence of radiation, much as Chechen rebels announced the presence of cesium 137 in a Moscow park in order to induce panic in 1995.

Ricks reported that, during the past 10 years, 53 radiation accidents (roughly half of them within the United States) have involved exposure to radiation that had significant medical consequences for 300 people, 33 of whom died.2 Ricks estimated that the entire human experience with radiation accidents involves 2,000 to 2,500 serious events worldwide (many of them never reported). The Oak Ridge database of reported events includes 424 major accidents, 3,059 significant human exposures, and 134 deaths. This experience has permitted treatment to advance to such a point that the immediate consequences of many exposures can be treated successfully (although long-term survival is less certain) using sophisticated medical procedures.

CONCLUSION

Unfortunately, this level of care calls for resources that could not be provided to a large number of patients simultaneously. Triage will be a critically important component of the response to any radiation disaster so that the most medically advanced treatment can be reserved for those most likely to benefit from it. Such decisions cannot be made in the absence of reliable radiation-dose estimates, so the radiology community may fill a vital role in helping triage teams calculate probable exposure levels based on the patient's symptoms and location at the time of the event. The role of consultant concerning decontamination and long-term health risks will also be important. Every community's disaster planning should involve radiology, and every radiologist, radiation oncologist, and medical physicist should help their community be prepared for radiation disasters.

Kris Kyes is technical editor of Decisions in Imaging Economics.

References:

1. American College of Radiology, American Society for Therapeutic Radiology and Oncology, and American Association of Physicists in Medicine. Radiation disasters: preparedness and response for radiology. Available at http://www.acr.org/departments/educ/disaster_prep/disaster_planning.html. Accessed July 22, 2003.
2. Van Moore A, Smith J, Ricks R. Paper presented at: 44th Annual Meeting of the American Society for Therapeutic Radiology and Oncology; October 5, 2002; New Orleans.
3. Hearings Before the Senate Committee on Foreign Relations. 107th Cong (2002) (testimony of Henry Kelly, president, Federation of American Scientists).
4. Charbonneau L. UN in dark about looted Iraq dirty bomb material. Available at: http://www.reuters.com/ newsArticle.jhtml?type=worldNews&storyID=3099769. Accessed July 21, 2003.
5. Man admits plotting Bangkok attack. Available at: http://stacks.msnbc.com/news/924653.asp. Accessed July 22, 2003.