CT Scans and Radiation Exposure: Emerging Legal Considerations for Imaging Manufacturers

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CT Scans and Radiation Exposure: Emerging Legal Considerations for Imaging Manufacturers

Rysavy: Dose and risk.

In hospitals, clinics, and unaffiliated radiologists' offices throughout the world, computed tomography (CT) scans are increasingly the diagnostic tool of choice. The reason for the explosive growth in these procedures is understandable, since the precision and clarity of newer generation CT scans make diagnoses quicker and more accurate, reduce the need for exploratory surgery (with all of its risks and potential complications), and save lives.

Over the past quarter century, the number of CT scans performed in the United States each year has increased more than 20 fold.1 Some physicians and clinics even promote whole-body CT scans as screening tools for asymptomatic patients. And as the technology of CT scans improves, so, too, does the range of practical applications and the raw number of CT scans performed on the populace of developed countries worldwide.

A Problem of Scale

As is virtually always the case with any medical procedure or test, however, the unquestionable benefits of CT scans do not come without risks. The primary risk from CT scans arises from the fact that every CT scan provides a nontrivial dose of ionizing radiation to the patient. For example, the average effective patient dose from a single CT scan ranges from 10 to 250 times the dose received from a normal chest x-ray, depending on the circumstances, with increasing doses for multiple scans. By way of perspective, the lowest effective radiation dose that a subject receives from a single CT scan is typically greater than the dose of radiation that the average U.S. nuclear plant worker receives in an entire year.2

Multiply the dose from a single CT scan by the increasingly large number of scans performed each year, and the collective dose to the U.S. population rises exponentially. In 2006, the collective CT dose to the U.S. population was approximately 44 million person-rem. This represents an increase in collective dose of greater than 700% since 1980. To place a collective dose of 44 million person-rem in perspective, in 1984 the annual collective dose for all 78 U.S. commercial nuclear reactors combined was roughly 55,000 person-rem. Today's larger fleet of reactors (104) has an annual collective dose of only 10,000 person-rem.

In the coming months, the National Council on Radiation Protection and Measurements (NCRP; Bethesda, MD), the preeminent U.S. independent scientific body on radiation health effects, is expected to announce that the annual average per capita radiation dose from clinical imaging exams in the United States will have risen 600%--effectively doubling the average background radiation dose to the general U.S. population—since the last publication of the report on U.S. public dose in 1987.3,4 Virtually the entire increase in background dose is due to diagnostic and therapeutic medical radiography, and approximately half of that dose is from CT scans.

Scientific and Medical Concerns

The scientific and medical communities have expressed concern over radiation doses to patients—especially those resulting from ‘unnecessary' CT scans and CT scans performed on children, who may be more vulnerable to adverse health effects from radiation. The concern about CT scan doses to children in particular is not without foundation, as more CT scans were performed on children last year than were performed on the entire population of the United States in 1980.1

The National Toxicology Program of the National Institute for Environmental Health Science (NIEHS; Research Triangle Park, NC) has considered classifying medical x-rays and CT scans as carcinogens in its biennial Report on Carcinogens.5 Risk coefficients published by the NCRP indicate that a 44 million person-rem collective dose to the U.S. population translates to an increased statistical risk of 22,000 fatal cancers per year.6 The New England Journal of Medicine recently published a study concluding that CT scans could be responsible for as much as 2% of all cancers in the United States during the next 20 to 30 years.1 An important caveat is that these statistics are based on scientific theories and conclusions that are susceptible to robust debate. Still, it would be unwise to ignore their potential impact.

Legal Considerations

Although there have been no reports in the legal press of lawsuits claiming radiation-induced cancers from CT scans, the issue has been attracting growing attention in that arena. The topic now also has the attention of the popular media, which has reported accounts of patients questioning the radiation dose received from CT scans, and in some instances refusing to undergo a scan due to concerns about radiation.7 And where public health risks emerge around a potentially toxic substance or medical procedure, entrepreneurial plaintiffs' attorneys seem sure to follow.

For the manufacturers of CT scanners, the most significant legal issues—if lawsuits indeed are filed—are design defect and failure to warn.

Design Defect. The primary question related to design defect will be whether the scanner that allegedly induced a given plaintiff's cancer could have been designed so as to produce images of the same or comparable quality while delivering a lower dose of radiation to the patient. During the past year, some manufacturers have rolled out new CT scanners designed specifically to reduce patient dose. The reduced radiation doses delivered by these manufacturers' scanners will probably be the minimum standard against which other manufacturers' scanners will be judged. They are likely to be used to counter any manufacturer's argument that low-dose CT scanners are not technologically feasible.

Shaw: Low-dose alternatives.

Industry leaders in low-dose CT scanners are not immune from suit either, since plaintiffs' experts are likely to opine that even the best models in the industry are inadequately designed to reduce patient radiation exposures to ‘safe' levels. Moreover, even industry leaders may face design defect claims related to older equipment still in service, or from their scanners purchased on secondary markets.

Failure to Warn. Plaintiffs will target both healthcare providers and manufacturers with failure to warn theories, claiming that patients were not provided with enough information about the potential risks of radiation exposure from CT scans to give truly informed consent to the procedure.

Such claims are likely to pit healthcare providers against manufacturers. Healthcare providers may assert that manufacturers did not provide sufficient information about risks to pass along to patients, supply enough risk information about device parameters to undertake an appropriate risk/benefit analysis, or provide sufficient information to perform the scans in a way designed to limit the patient's dose. By contrast, manufacturers may argue that they provided sufficient information about the potential risks, and that in some circumstances (e.g., whole-body screening of asymptomatic individuals) the CT scans at issue were of questionable medical necessity.

Defensive Measures

Notwithstanding these theories, there are strong defenses that scanner manufacturers can use to guard against claims for radiation-related cancers. The most compelling defense argument is likely to be one of risk/benefit—that the possibility of cancer many years or decades in the future is virtually always trumped by the immediate risks to the patient that necessitated the use of a CT scan in the first place.

It will also be difficult for plaintiffs to argue convincingly that, had they been provided with sufficient information about the potential—and likely very small—risk of future cancer from a CT scan, they would have chosen instead the immediate, perhaps life-threatening, consequences of refusing the scan. These defenses would also be available to healthcare providers, except perhaps where plaintiffs have claims of unnecessary testing or screening.

Although there will be strong defenses available to counter such lawsuits if and when they are filed, there are nevertheless some claims-avoidance actions that a prudent manufacturer may wish to consider now. These include the following, as appropriate for the manufacturer's products.

  • Review and revise existing product warnings as necessary, both for new-generation and older scanners.

  • Undertake a direct education program about radiation risks from CT scanners for prescribing physicians and radiologists (these professionals receive very little training about radiation risk in medical school).

  • Provide devices to measure patient dose from CT scans, and encourage radiologists to record this information in patient charts.

  • Evaluate insurance coverage for potential liabilities.

  • Review the in-house paper trail on this issue for vulnerabilities.

  • Consider whether all reasonable efforts within the manufacturer's control are being made to minimize radiation doses to patients.

Undertaking even a few of these efforts is good claims avoidance, and can pay dividends if claims are actually filed.


1. DJ Brenner and EJ Hall, “Computed Tomography: An Increasing Source of Radiation Exposure,” New England Journal of Medicine 357, no. 22 (2007): 2277–2284.

2. Occupational Radiation Exposure at Commercial Nuclear Power Reactors and Other Facilities, 2006,” NUREG-0713, vol. 28, (Washington, DC: U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, 2007); available from Internet: www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0713/v28/sr0713.pdf.

3. RC Rabin, “With Rise in Radiation Exposure, Experts Urge Caution in Tests,” New York Times (June 19, 2007 [cited 18 December 2008]): XXX–XXX; available from Internet: www.nytimes.com/2007/06/19/health/19cons.html.

4. Ionizing Radiation Exposure of the Population of the United States, NCRP Report 93 (Bethesda, MD: National Council on Radiation Protection and Measurements, 1987).

5. Report on Carcinogens, 11th ed. (Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service, National Institute of Environmental Health Sciences, National Toxicology Program, 2005 [cited 15 December 2008]); available from Internet: http://ntp.niehs.nih.gov/index.cfm?objectid=32BA9724-F1F6-975E-7FCE50709CB4C932.

6. Limitation of Exposure to Ionizing Radiation, NCRP Report 116 (Bethesda, MD: National Council on Radiation Protection and Measurements, 1993).

7. B Casey, “CT Experts Grapple with Rising Concerns about Radiation Dose” [online] (May 14, 2008 [cited 18 December 2008]); available from Internet: http://www.auntminnie.com/index.asp?Sec=sup&Sub=bai&Pag=dis&ItemId=81091.

Charles F. Rysavy is a partner and Roger P. Shaw is a technical specialist in the law firm of K&L Gates LLP (Newark, NJ).

© 2008 Canon Communications LLC

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