Point-Counterpoint: Imaging dose

Point: ACR deems government oversight unworkable, but offers other steps

By the American College of Radiology

Direct FDA jurisdiction over how CT scanners are used, including radiation dose requirements, as suggested recently by an article published online in the New England Journal of Medicine, is likely a logistical impossibility given the number of scanner types and their generations in use and the variety of indications for which medical imaging serves an appropriate role. Narrowly defined regulations may not allow for the flexibility that physicians need to provide the best possible care for their patients.

The American College of Radiology and the Society of Computed Body Tomography and Magnetic Resonance (SCBTMR) affirm that a more immediate and, ultimately, more effective way to address the issues of radiation dose and appropriate utilization of imaging exams is for the government to require that all imaging providers adhere to existing, previously voluntary, programs that the American College of Radiology and other imaging stakeholders already have in place and that have been proven effective:

• Computerized exam ordering systems based on the American College of Radiology Appropriateness Criteria help doctors prescribe the best exam for a patient’s given condition, inform them when an exam that does not use radiation may be more appropriate, and notifies them when no scan may be warranted at all. This reduces unnecessary exams and radiation exposure to patients.

• ACR facility accreditation requires facilities to maintain image quality, checks radiation dose used, and minimizes the likelihood of adverse events such as those highlighted in recent news reports by requiring that physicians meet certain education/training standards, scanners be surveyed regularly by a medical physicist to ensure proper function, and technologists operating scanners be certified.

• The ACR CT dose index registry will allow providers to submit radiation dose data so that facilities may compare their CT dose indices against realistic national benchmarks and may reexamine their imaging protocols if necessary. It will also alert facilities if a dose threshold has been exceeded.

Since 2002, the ACR’s Diagnostic Reference Levels (DRL) have outlined dose levels that CT scans should not normally exceed while recognizing that there may be certain instances when dose would have to be increased, such as in the case of morbidly obese patients. The ACR and SCBTMR support the National Council of Radiation Protection and Measurements’ effort to develop more detailed reference levels to include more exam types and body areas. The ACR CT dose index registry will aid in the development of DRLs and provide scientific feedback regarding the effectiveness of radiation dose reduction efforts over time.

These efforts can cut down on radiation dose received from duplicative scans, help to ensure that patients receive appropriate dose per scan, and set in place a nationwide standard of care so that people in the U.S. can expect quality imaging regardless of where they live.

Medical imaging exams have been directly linked to greater life expectancy and declines in cancer mortality rates, and they are generally less expensive than the invasive procedures they replace. No imaging exam should be performed unless there is a clear medical benefit that outweighs any theoretical risk. The ACR and SCBTMR support the “as low as reasonably achievable” (ALARA) concept, which urges providers to use the minimum level of radiation needed in imaging exams to achieve the necessary results.

Lawmakers and government agencies need to work with the provider community to help ensure that the next steps taken to address the very important issues of medical radiation reduction and necessary utilization are the correct steps. Federally mandating participation in these existing programs can help ensure that medical imaging is safe, effective, and available without removing treatment decisions from doctors’ hands and without further stressing the American healthcare system.

The ACR urges patients and providers to visit the “Radiology Safety” section of the ACR website as well as the Radiation Safety section of www.radiologyinfo.org, the patient information site comanaged by the ACR and the Radiological Society of North America (RSNA), and the Image Gently site for more information regarding radiation exposure from medical imaging exams.

Patients should also keep a record of their x-ray history and before undergoing a scan, should ask their physician:

• Why do I need this exam?

• How will having this exam improve my healthcare?

• Are there alternatives that do not use radiation that are equally good?

• Is this facility ACR accredited?

• Is my child receiving a “kid-size” radiation dose (for pediatric exams)?

Helpful Resources:

ACR Accredited Facility Search PageACR Appropriateness Criteria
ACR Appropriateness Criteria help physicians prescribe the most appropriate imaging exam for more than 200 clinical conditions (particularly when an imaging exam that does not use radiation may be more appropriate for a given condition).

Radiation Exposure Estimates from Common Imaging ProceduresRadiation Safety Section of the ACR Web SiteACR Statement on Whole Body CT Scans

Counterpoint: Dose reduction systems need to be comprehensive, rigorously enforced, and tested

 By Rebecca Smith-Bindman, M.D.

I think we need a comprehensive, systems-based approach to ensure that patients get the lowest doses possible on imaging examinations. The system we adopt should be one that is rigorously tested and shown to have the desired impact of lowering typical and outlying radiation doses patients receive.

While there are different potential approaches that could work to standardize CT and improve its safety, any system that we adopt should assess the radiation received by most patients (not a very small handful of selected patients as occurs with the ACR accreditation process) and should capture the majority of doses and types of tests received. Not all, but most.

If a facility, for example, chooses to use very high dose procedures in the majority of patients, but submits the scan for a patient who happened to receive a low-dose study, this disparity would never be reflected in the system adopted by the ACR when reporting on a facility’s performance. I am not comfortable with a system that learns about the quality of imaging by asking facilities to send in their best work as I do not know how this reflects the quality of the entirety of the imaging received at the facility.

Thus dose collection needs to be comprehensive. Further, we cannot collect data on only a handful of protocols if hundreds of protocols are used. The information we assess should be the same information that a patient wants and needs when he or she goes to a facility for a scan. What is the dose I am likely to receive and is it as low as possible to make a diagnosis?

While I applaud the efforts of the dose registry, it is currently a tiny, underfunded operation and should not be endorsed as the system we use to make CT as safe as possible in this country without much more evidence of its capacity to collect, analyze, report, and share data in a meaningful fashion.

If such a system is going to be our solution to radiation safety, these data must be publicly available. Further, the system should have a demonstrated effect of reducing the doses patients typically receive at these facilities. I think this system could work, but as far as I can tell, it would have to greatly expand and its results would have to be broadly reported in the scientific community (and their impact shown) before it could become a system that should be endorsed.

I agree it is difficult to collect dose information given the variation by manufacturer, machine type, and patient characteristics; limitations in estimating dose accurately in atypical patients; and variation that results from how physicians and technologists set up the scans. As a community, we in the U.S. have not collected or assessed dose very well because of this difficulty. Physicians and technologists are ill-educated about dose-or simply don’t care about dose.

Because it’s been difficult, we have avoided our responsibility to ensure we use radiation wisely. However, most of Europe and many other nations have managed to put considerable effort into precisely such an endeavor, and have had a very positive impact on quality, standardization, and safety. We have some catching up to do, and I believe we can markedly reduce the doses patients receive immediately by making radiation safety a priority. This would involve expanding education of radiologists and technologists about the known carcinogenic effects of radiation-not denying the known effects, which only serves to mislead and confuse patients, technologists, and physicians.

We need to quickly educate healthcare personnel about the benefits of reducing doses. And we need to make techniques for dose reduction widely available, at a lower cost than is currently available. I personally think the radiology leadership organizations, such as the ACR and RSNA, could have a huge impact by educating their memberships on this issue and by providing and sharing techniques of dose reduction.


Dr. Smith-Bindman wrote a June 23, 2010, perspective article in the online New England Journal of Medicine calling for regulation by the FDA of imaging dose levels. She is a professor in the University of California, San Francisco radiology and biomedical imaging, epidemiology and biostatistics, and obstetrics gynecology and reproductive sciences departments. She is also a visiting research scientist at the Radiation Epidemiology branch of the National Cancer Institute.