A chest computed tomogram (CT) corresponds to about 400 chest x-rays, implying a risk similar to smoking 700 cigarettes

Radiological Risks: A Newsmaker Interview With Eugenio Picano, MD

Oct. 8, 2004 — Editor's Note: Although the ionizing radiation associated with commonly performed radiological examinations is associated with a low, but definite, long-term risk of cancer, patients are often poorly informed of these risks, according to an article in the Oct. 9 issue of the British Medical Journal . Even radiologists and nuclear medicine physicians may be unaware of the doses and risks involved.

Lack of informed consent for radiological procedures violates patients' rights and basic tenets of modern medicine, according to author Eugenio Picano, MD, a clinical cardiologist at the Institute of Clinical Physiology of the National Research Council in Pisa, Italy. Risk assessment is uncertain and explaining that risk to the patient may be even more fraught with difficulty, but Dr. Picano believes that this does not absolve the physician of the responsibility to communicate basic information. To facilitate this process, he recommends a communication method suggested by the U.K. College of Radiologists and endorsed by the European Commission's guidelines on imaging, which is to express the dose as multiples of a chest x-ray and the risk of cancer as the number of extra cases in the exposed population.

To learn more about the clinical issues involved in informed consent for radiological examinations, Medscape's Laurie Barclay interviewed Dr. Picano, who is also the scientific director of cardiology at the Clinica Cardiologica Montevergine in Mercogliano, Avellino. This clinic has the highest volume of invasive cardiology procedures in Italy.

Medscape: How great is the risk incurred in some of the more common radiological examinations compared with other risks of daily life?

Dr. Picano: For example, a chest computed tomogram (CT) corresponds to about 400 chest x-rays, implying a risk similar to smoking 700 cigarettes. Here, we have a paradox: in Europe, when you buy a cigarette pack you are faced with a large, bold, and funereal black notice stating that "Smoking severely damages your health" or "You can die from smoking"; then you have a thallium scan, and no one minds telling you that the long-term risk corresponds to smoking 1,400 cigarettes.


Medscape: How well informed are most physicians about the risks of radiological procedures, and what can be done to improve their level of awareness?

Dr. Picano: Unfortunately, several recent studies clearly prove that not only general practitioners, but also cardiologists, orthopaedists and even radiologists and nuclear physicians usually ignore the dose and the risk of what they do, and the more they do, the more they tend to ignore. Radiologists working in an academic U.S. environment frequently underestimate by 100 to 500 times the dose of a common CT [Lee CI, et al, Radiology. May 2004;231(2):393-398]. Italian cardiologists underestimate by 200 times the dose of a stress cardiac perfusion scintigraphy [Correia et al, abstract presented at the American Heart Association meeting, November 2003]. Ninety-seven percent of U.K. doctors underestimate by 16 times the dose of a common CT chest scan, and one out of 10 even believes that magnetic resonance employs ionizing radiations [Shiralkar S, BMJ. Aug. 16, 2003;327(7411):371-372].

The systematic use of a clear and simple informed consent form spelling out doses and risks of common ionizing test examinations is an easy way to inform not only patients but also doctors about what they are doing. After all, ignorance of the prescriber/practitioner can be considered a circumstance which evangelically attenuates responsibility: "Father, forgive them, for they know not what they do" [Luke 23:34]. However, law does not tolerate ignorance. Also, psychologists question the possibility that ignorance can attenuate responsibility. According to psychoanalyst Bruno Bettelheim, the guilt of Oedipus — who killed his father and slept with his mother — stems from his nonwillingness to know, and the myth teaches on the destructive consequence of acting without knowing what you are doing.


Medscape: How often do physicians obtain informed consent for radiological procedures, and what is the quality of the information given?

Dr. Picano: Physicians usually don't ask for informed consent for radiological procedures on the basis of the view that they are too wise to make inappropriate examinations and too busy to lose time with informed consent. This is perhaps true in the ideal Republic of Plato, but not in the everyday clinical practice of industrialized societies.

Medscape: How do physicians attempt to justify not informing patients of radiological risks?

Dr. Picano: Physicians have basically four arguments. First is efficiency bias: informing patients would be a loss of time. Second is expert bias: only appropriate examinations are done, and the specialist knows best. Third is paternalistic bias: to describe every small risk is a form of anxiety-generating psychological terrorism. Fourth is uncertainty bias: current best available estimates of risk for low-dose exposures are surrounded by uncertainties and approximations. The end result of this approach is that at least 30% of ionizing test examinations are totally or partially inappropriate, as recognized by experts, scientific societies, the European Commission, and the Food and Drug Administration.

Medscape: Why is it necessary to inform patients of these risks, and what is the harm in not informing them?

Dr. Picano: In a perspective of shared decision-making, the patient has the right to know, and the physician has the duty to inform. This is required by ethical reasons, deontologic code, and, in many countries, by the existing law.

Medscape: What are the various strategies physicians use in communicating radiological risk?

Dr. Picano: In currently used informed consent forms there are three basic philosophies of risk communication: no mention of risk, understatement of risks, and specific detailing of risks. The first, "don't say a word" approach is the most used in radiology; the second is the most used in nuclear medicine; the third one, full disclosure, is used for irradiation within research projects but should be extended to examinations performed for clinical reasons.

Medscape: How effective are these strategies?

Dr. Picano: These strategies have very poor results, since, as repeatedly shown in different medical environments, on average there is no awareness of doses and risks by either the patient or the physician, and the number of useless ionizing test examinations is escalating.

Medscape: What strategy do you recommend that physicians use to communicate with patients about radiological risk?

Dr. Picano: The principle of patient autonomy in current radiological practice might be reinforced by making it mandatory to obtain informed consent for all examinations involving high radiological dose, that is, those with an associated long-term risk of fatal cancer of 1 in 10,000 or higher, with the consent form possibly incorporating a graphical portrayal of risk to make communication easier and faster.

Medscape: What policy should hospitals adopt regarding informed consent for radiological procedures?

Dr. Picano: Health professionals prescribing and/or performing radiological and nuclear medicine examinations should overtly spell out the radiation dose and risk associated with some common radiological and nuclear medicine examinations. For instance, the dose of 50 chest x-rays, for example, a lung scintigraphy, corresponds to an extra risk of fatal cancer of about 1 in 20,000 exposed patients. The dose of 500 chest x-rays (such as a technetium sestamibi cardiac stress scan) corresponds to an extra risk of about 1 in 2,000 exposed patients. The dose of 1,000 chest x-rays, slightly less than that associated with a thallium scan, corresponds to an extra risk of about 1 in 1,000 exposed patients. This format might be useful for passing information from doctors to patients and between doctors.

Medscape: What is the impact of unnecessary radiological testing on population safety?

Dr. Picano: Small individual risk multiplied by billions of examinations per year represents an important population risk. The lifetime risk of developing cancer attributable to diagnostic x-rays is around 2%, according to recent estimates referred to radiological volumes of 10 years ago [Berrington de Gonzalez A and Darby S, Lancet. Jan. 31, 2004;363(9406):345-351]. Since then, radiological and nuclear medicine volumes increased at least sixfold [Picano E, Lancet. June 5, 2004;363(9424):1909-1910]. The best way to achieve safety is to increase the radiological awareness of doses and risks among health professionals and patients.