ACR Responds to NEJM Article on Radiation Risk Associated With CT Scans


The American College of Radiology (ACR) is concerned that certain conclusions and comparisons made in the study, “Computed Tomography — An Increasing Source of Radiation Exposure,” published in the Nov. 29 issue of the New England Journal of Medicine, may be inappropriate and cause patients to mistakenly avoid getting life-saving medical imaging care.

The study claims that up to 2 percent of all cancers in the United States may be caused by radiation received from CT scans. Yet, the study authors admit that there are currently no published studies directly linking CT scans (even multiple CT scans) to cancer.

The study also equates radiation exposure and effects experienced by many atomic bomb survivors in Japan to present day patients who receive computed tomography (CT) scans. Most CT exams are performed in a controlled setting. They result in limited radiation exposure to a small portion of the body. Atomic bomb survivors experienced instantaneous radiation exposure to the whole body. Also, CT exams expose patients solely to X-rays. Atomic blast survivors were exposed to X-rays, particulate radiations, neutrons, and other radioactive materials. The known biological effects are very different for these two scenarios.

“Patients need accurate information on which to base their health care decisions. They may be terribly confused and unduly distressed by some of the statements in this study,” said Arl Van Moore Jr., M.D., FACR, chair of the ACR Board of Chancellors.

There is little doubt in the medical community that CT scans help save lives. Advancing technology has increasingly allowed imaging exams to replace more invasive techniques, but has also resulted in increased radiation exposure for Americans.

The College urges patients and providers to visit the “Radiology Safety” section of the ACR Web site as well as the “Radiation Safety” section of www.radiologyinfo.org, the patient information site co-managed by the ACR and the Radiological Society of North America (RSNA), 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 health care?
  • Are there alternatives that do not use radiation which are equally as good (e.g.. MRI, ultrasound, etc.)
  • Is this facility ACR accredited? (ensures that physician and staff meet education and training standards and that equipment is surveyed regularly by medical physicist to ensure that it is functioning properly)

“The College has long held that no medical test, particularly those utilizing ionizing radiation, should be performed unless the medical benefits clearly outweigh any risk associated with the exam. For example, the ACR has long opposed full body CT scans for asymptomatic patients, one of the exams that the NEJM article authors put forth as a driver of future CT growth,” said ACR Chair Moore. We also support the ‘as low as reasonably achievable’ (ALARA) concept which urges providers to use the minimum level of radiation needed in such exams to achieve the necessary results.

The ACR has led the effort to eliminate unnecessary radiation dose in imaging for decades. Historic ACR actions to monitor and reduce radiation dose include:

  • ACR Appropriateness Criteria (1993) which help radiologists and referring physicians prescribe the most appropriate imaging exam for more than 200 clinical conditions (can help patients avoid unnecessary exposure to scans utilizing radiation when others such as MRI and ultrasound, which do not use radiation, may be better for that particular condition)
  • Accreditation of facilities which offer X-ray technologies (including dose assessments)
    • Mammography (1987)
    • Stereotactic Breast Biopsy (1996)
    • CT (2002)
  • Practice Guidelines and Technical Standards (1990) which layout the acceptable protocols for performing imaging exams (including CT).

ACR activities to lower radiation dose were recently summarized in the ACR Whitepaper on Radiation Dose in Medicine published in May 2007. In the paper, the ACR Blue Ribbon Panel on Radiation Dose also outlined 33 specific action items to help reduce radiation dose. Below are items already in motion:

  • Creation of a Dose Registry (2008) including CT dose and the ability to establish bench marks.

  • Working with other medical specialties on radiation dose awareness. An example of this is the upcoming “Consensus Conference on Imaging Safety and Quality for Children in the Emergency Setting” scheduled for Feb. 2008 (cosponsored by the Society for Pediatric Radiology).  

The ACR will continue to work with congress, government agencies, other medical specialties, and public and private payers to improve quality and reduce unnecessary radiation exposure for patients.