Re-Imagining Medical Treatment & Removing Security Risk
Recent terrorist attacks in Paris, Brussels, and Turkey have renewed concerns that terrorists could use widely available radiological sources to carry out an attack that would contaminate large areas, create social panic, and disrupt economies. In order to prevent terrorists from acquiring such “weapons of mass disruption,” governments such as the United States and France are increasingly looking to find ways to substitute other materials for the most dangerous of these commercially available radioactive sources, which are used for applications as wide-ranging as digging oil and gas wells or sterilizing food. Reducing the use of high-risk sources in medical applications has been a particular focus, because the openness and accessibility of medical facilities can make them vulnerable to terrorists and the sources there are potentially highly dangerous. At the same time, such a replacement process is more feasible in medicine than some other fields as equivalent non-isotopic alternatives are already in significant commercial use.
Experts generally consider sources with cesium-137, particularly in its cesium chloride form, to be the commercial source that poses the greatest terrorist risk. Widely used in medicine to irradiate blood to prevent transfusion-associated Graft vs. Host disease, cesium chloride is a talcum-like powder that is easily dispersible by a “dirty bomb” and soluble in water. Combined with its strong radioactive emissions and long (30-year) half-life, it could easily penetrate skin and render soil, buildings, and water systems unusable for decades.
Click the play button to learn more about a re-imagined LINAC with this interactive 3D model
Japan and many countries in Western Europe have turned to two other technologies for blood irradiation that don’t pose the same security risks: x-rays and a photochemical process using ultraviolet light. For examples, in March 2016, Emory University, with the support of the Nuclear Threat Initiative (NTI), installed an alternate technology that uses x-rays to replace its existing cesium chloride blood irradiator. A 2008 U.S. National Academy of Sciences report called for replacing cesium chloride blood irradiators with less hazardous alternatives, but the academy’s recommendation has not yet been fully embraced by an interagency task force of the federal government chaired by the Nuclear Regulatory Commission.
Cobalt-60 is another radiological material used in medicine and viewed as posing a serious risk. Often used in low and middle-income countries (LMIC) for external cancer radiation treatment, cobalt-60 is a strong source with a significantly long half-life (more than five years). Many times clinics or hospitals in these countries lack the funds to dispose of disused sources properly and more than once they have ended up in scrapyards where they have contaminated whole communities. For example, in 2000 in Thailand a junkyard worker cut open a source, leading to the exposure of nearly 2,000 people, with 10 people developing radiation poisoning, and three dying within two months.
In higher-income countries, cobalt-60 radiation treatment machines largely have been phased out in favor of linear accelerators (LINACs) that don’t carry the same security risks and are viewed by medical practitioners as providing better treatment. However, these accelerators often are more expensive, require more maintenance and training to operate, and can function less effectively in challenging environments (such as those with irregular electric power, and uncertain water and air conditioning systems). These challenges are particularly important to overcome at a time when the cancer burden in low and middle income countries is growing enormously. Right now, many of these countries continue to rely on the cobalt-60 technology which creates a security risk.
Developing linear accelerators that operate effectively in these countries is a necessity. What does that mean? This reimagined machine [or equipment] should be less expensive; mobile; modular in components (perhaps even using 3d-printable parts); have an open design with certification in mind; and be easier to operate—all while still maintaining the same treatment capability as more expensive linear accelerators. While an enormous technical challenge, such machines would not only benefit low-income countries but the rest of the world as well. To provide “treatment, not terror” to all countries worldwide, regardless of their economic or political circumstances, is both an engineering challenge and a humanitarian requirement.