CT Scanning and Cancer: Why You and Your Family Are at Risk, Part I An Expert Interview With Richard C. Semelka, MD

April 25, 2006

Editor's Note:
Because of the documented link between radiation exposure and computed tomographic (CT) scanning, careful attention should be paid to the number of CT studies performed on any one patient and a determination should be made as to whether effective, alternative, and safer imaging strategies can be performed for any indication, according to Richard Semelka, MD, Professor and Vice Chairman, Department of Radiology, University of North Carolina at Chapel Hill.

Dr. Semelka's recent article, "Imaging X-rays Cause Cancer: A Call to Action for Caregivers and Patients" (posted at https://www.medscape.com/viewprogram/5063), has launched an avalanche of email correspondence to Medscape from imagers and patients. In this CME/CE article, Dr. Semelka postulates that it is critical for radiologists and referring physicians to scrutinize how often a patient is undergoing a CT study and to determine whether magnetic resonance imaging (MRI), in many settings, can replace CT.

Dr. Semelka recently sat down with Medscape to expand on the points made in his CME article and to provide imaging professionals and patients with additional perspectives regarding safe and effective imaging options.

Medscape: Dr. Semelka, what, in your estimation, is the greatest challenge facing the radiology community?

Dr. Semelka: From my perspective, the most critical challenge that radiologists face today is the post BEIR VII environment that we now practice under.

Medscape: For our readers who may not be familiar with the BEIR VII, that's the landmark study reporting on radiation risks associated with imaging x-rays, correct?

Dr Semelka: Correct. The report was issued by the National Academy of Sciences in the fall of 2005. The National Academy of Sciences is the largest scientific body in the world. The focus of their report was the part that ionizing radiation plays in the development of cancer. The benchmark that they came up with is that an x-ray exposure of 10 mSieverts (mSv; units that radiation dose is measured in), which is roughly equivalent to the radiation a patient is exposed to with a CT study of the chest or a CT study of the abdomen, produces cancer in 1 per 1000 patients.

So, now we have to take that issue into consideration as we move forward in radiology.

Other key issues confronting the specialty include the introduction of new and very exciting technology in areas such as CT, nuclear medicine and positron emission tomographic (PET) scanning, and MRI. And then there is the challenge of training young radiologists in the university setting and the private-practice setting to elevate the level of imaging diagnoses and healthcare in the general patient population; In my mind, diagnostic imaging has become the modern physical exam. In the near future, virtually every individual suspected of having disease will undergo a cross-sectional imaging study.

Medscape: So, you envision that radiology will become a much more important and "mainstream" medical specialty over the next 10-20 years?

Dr. Semelka: Absolutely. Basically, most diagnoses will be made on the basis of the imaging study, perhaps only on the basis of the imaging study.

Medscape: So, will the whirlwind development of new imaging technologies vs an awareness on the part of patients concerning the potential dangers associated with some of these new technologies trigger a new radiology practice paradigm?

Dr. Semelka: Of course. And this new practice paradigm will center around the following factors. The first factor is improving the accuracy and consistency of patient diagnosis across the spectrum of diagnostic imaging modalities. And, we now have to pay a lot more attention to patient safety, to the extent that we need to be absolutely certain that we are not causing diseases such as cancer by performing a particular study.

Medscape: Let's focus on the safety issue. How did we get to a place in which patients are not told about the safety risks associated with imaging studies that employ x-rays, and why is it that radiologists don't seem to want to address the issue?

Dr. Semelka: Let's start with the patients. I think that, ultimately, the major moving force behind addressing the CT radiation risk issue will be mediated by patient desires and concerns. Patients are becoming technologically savvy, and they tend to go online to find out information. We are entering a new era of patient-driven care in which patients will not only be personally responsible for determining the type and quality of care they receive, but will also be at least partially financially responsible through the introduction of personal healthcare accounts and other factors. I believe that patients will lead the charge toward reforming the ways in which CT scanning is employed.

Ultimately, I would prefer to see that charge led from the standpoint of doing the right thing, and looking at what the extrapolated data mean regarding excessive CT use and the development of cancer. Radiologists need to talk to their patients. We have to think about CT use, because CT may result in cancer. What I hope to see is a change in the way that radiologists think, driven by patient demand, so that it is clear that in certain settings we are doing a disservice if we order multiple CT scans, especially in the young.

Medscape: Do you really think that ordering patterns by referring physicians can be changed, given the practice of "defensive medicine"?

Dr. Semelka: Many radiologists have been passive when it comes to doing whatever the referring physician requests. The referrer would send the radiologist a case requesting specific diagnostic information; in many instances, the patient would report to the imaging center and interact with the technologist and never see the radiologist. The study would be performed, the radiologist would read the study and give the report to the referring physician, and then the referring physician would speak to the patient. The radiologist was separated from the patient and unaware of the patient's needs and questions.

I think that in the current environment post BEIR VII, in which safety and informed consent is a potent issue, it's a patient's right to obtain whatever study he or she wants. Patients have an absolute right to know that the equipment the radiologist is using is current, and that the physicians interpreting the imaging data are highly trained and up-to-date in terms of their knowledge of disease. I think it's their right.

The bottom line is that the radiologists need to become more consultative with the patients who are referred to their imaging center. For example, many patients do not even know whether the equipment in the imaging suite is up to specification. That is a simple question that can be asked of the radiologist in advance of the study that can go a long way in allaying patient concerns. For example, the patient may want to know, "Is the system that I'm going to be imaged by relatively new?" Equipment that was made within the past 3 years is considered relatively new and adequate. Patients also might want to know, "Are you, as my radiologist who is going to be interpreting my study, experienced in the acquisition and interpretation of these images?" It is now the inalienable right of every patient to ask these questions of every radiologist.

And if the center director or radiologist on call does not want to sit down with the patient and have a dialogue, the patient should go to another imaging center - patients can either find one on their own or request that the referring physician send them to a different center.

Although patients have always had a right to know what was in store for them, in the past, it was in the interest of referring physicians and imagers to convey that an x-ray-based study, like a blood test, was just another diagnostic test.

Well, it's not.

All diagnostic imaging studies rely on the kind of equipment used, the quality of the images captured, and the talent and training of the individual who is going to interpret the pictures.

Patients must be aware of these factors and must recognize that they can demand to be studied by extremely talented individuals using extremely good equipment.

That is every patient's right. That's number one.

Look for Part II of Medscape's Expert Interview with Richard Semelka, MD, on the Medscape Radiology site.