eLetters to:

FROM THE AMERICAN ACADEMY OF PEDIATRICS: Alan S. Brody, Donald P. Frush, Walter Huda, Robert L. Brent and the Section on Radiology Radiation Risk to Children From Computed Tomography Pediatrics 2007; 120: 677-682 [Abstract] [Full text] [PDF]

eLetters: Submit a response to this article

eLetters published:

Radiation risk to children from CT

Manoj K Mittal   (17 October 2007)

Reply to Dr. Mittal

Alan S. Brody, Donald P. Frush, Walter Huda, and Robert L. Brent   (23 October 2007)

Unrecognized Risks of Pediatric CT scans: reply to Dr. Mittal

Devra L. Davis, PhD, MPH, Maryann Donovan, MPH, PhD, and Deborah Axelrod, MD   (20 February 2008)

Radiation risk to children from CT 17 October 2007
Manoj K Mittal, MD Division of Emergency Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA Send letter to journal: Re: Radiation risk to children from CT Mittal{at}email.chop.edu Manoj K Mittal	I congratulate Brody et al from the AAP Section on Radiology for their timely clinical report on radiation risk to children from computed tomography (1). In discussing radiation risks with our patients and their parents, I think that it would also be useful to mention the estimate of increased risk of cancers or number needed to harm with radiation. The BEIR statement released in 2005 puts the risk of developing cancer from a 10 msv dose (e.g. from CT of abdomen and pelvis as for the diagnosis of appendicitis) in adults at 1 in 1000 (2). As the authors of the report acknowledge, this risk is likely to be higher for children. Another important issue is the effect of radiation on the developing brain in youg children. There is emerging evidence that radiation doses equivalent to that used for head CT in infancy may influence cognitive abilities in adulthood. Hall et all showed in their population based cohort study that infants who received radiation therapy (dose equivalent to that for head CT) to head for cutaneous hemangioma were less likely to attend high school and performed significantly poorer on cognitive tasks than controls (3). References 1.Alan S. Brody, Donald P. Frush, Walter Huda, Robert L. Brent and the Section on Radiology. Radiation Risk to Children From Computed Tomography. Pediatrics 2007; 120: 677-682 2.National Research Council, Committee to Assess Health Risks From Exposure to Low Levels of Ionizing Radiation. Health Risks From Exposure to Low Levels of Ionizing Radiation: BEIR Phase 2 (2006). Washington, DC: National Academies Press; 2006. Available at: http://books.nap.edu/catalog/11340.html. Accessed September 22, 2007. 3.Hall P, Adami HO, Trichopoulos D, et al. Effect of low doses of ionising radiation in infancy on cognitive function in adulthood: Swedish population based cohort study. BMJ. 2004;328(7430):19 Conflict of Interest: None declared
Reply to Dr. Mittal 23 October 2007
Alan S. Brody, Pediatric Radiologist Cincinnati Children's Hospital and the University of Cincinnati College of Medicine, Donald P. Frush, Walter Huda, and Robert L. Brent Send letter to journal: Re: Reply to Dr. Mittal alan.brody{at}cchmc.org Alan S. Brody, et al.	To the Editor; We thank Dr. Mittal for his congratulations and for his letter. Dr. Mittal raises two important points; specific estimates of increased risk of cancer, and ionizing radiation effects other than increased cancer risk. Estimates and projections made by expert committees of the cancer risks of low exposures of radiation have been published, including the BEIR VII report. These projections are based on data from populations exposed to other radiation than CT scans, particularly individuals exposed to the atomic bomb. There are no data based on children or adults exposed to radiation from CT scans. Authorities including the BEIR committee explicitly state that there are large uncertainties in risk estimates for low doses given the limited empirical data. Since radiation oncogenesis is a stochastic effect (there may not be a threshold), there is a possible oncogenic risk even at low exposures. The authors of the Statement, have refrained from providing risk estimates such as 1 in 1000 or 1 in 10,000 because the actual risks are not known. Multiple expert review committees for this Statement also supported this perspective. The effect of ionizing radiation on the developing brain is an area with limited, and again, controversial data available. Different considerations apply in regard to central nervous system effects as there is a threshold, and so this is not a stochastic effect. It was not our charge to draw any conclusions about radiation exposures that have the potential to affect cognitive behavior at this time. Conflict of Interest: None declared
Unrecognized Risks of Pediatric CT scans: reply to Dr. Mittal 20 February 2008
Devra L. Davis, PhD, MPH, Director, Center for Environmental Oncology University of Pittsburgh Cancer Institute and Graduate School of Public Health, Maryann Donovan, MPH, PhD, and Deborah Axelrod, MD Send letter to journal: Re: Unrecognized Risks of Pediatric CT scans: reply to Dr. Mittal davisdl{at}upmc.edu Devra L. Davis, PhD, MPH, et al.	Regarding the risks of pediatric CT, Mittal raises important points that are relevant to the interpretation of Brody et al., 2007. There are no empirical data on children who have undergone CT scans, despite the fact that there has been a significant increase in such scans in the past decade, according to several sources. Studies from Chernobyl survivors indicate that the radiogenic cancer risk to infants and children is likely to be greater than that observed in adult Hiroshima/Nagasaki survivors.(1) For instance, unprecedented increases in thyroid cancer in children and young adults have been linked with Chernobyl.(2) The American College of Radiology,the National Cancer Institute and the Society for Pediatric Radiology are (3) to be applauded for their efforts to: inform other medical professionals of the need to restrict CT scans to emergencies; promote the standardization of radiation-dose estimates; encourage certification and training and retraining of medical professionals regarding estimated doses of CT scan and the value of alternative non-ionizing radiation diagnostic technologies, such as ultrasound and Magnetic Resonance Imaging; promote the creation of federal standards, as exist for mammography, for CT technologists. The public and some health professionals are unaware of the doses of radiation that can be involved in CT scans of infants and young children and the wide range of radiation that can be involved in any procedure. One way of conveying the relative doses is by comparing them to those involved in ordinary chest x-rays. The attached table shows the estimated equivalency in chest x-rays and may be a useful tool to inform health professionals of the importance of curtailing inappropriate uses of CT scans. Table 1 --- Radiation Risks of CT Scans. Exam Type Machine Setting* Relevant Organ Approx. Equivalent Dose to Relevant Organ (mSv) Equivalency in Chest X-rays .15-.01 mSv** Source: Society for Pediatric Radiology and National Cancer Institute, 2002. Radiation & Pediatric Computed Tomography: A Guide for Health Care Providers. * "Unadjusted" refers to using the same settings as for adults. "Adjusted" refers to using settings adjusted for body weight. ** Chest-x-ray equivalency based on NCI estimates in this table Pediatric Head CT Unadjusted Brain 60 400-6000 Pediatric Head CT Adjusted Brain 30 200-3000 Ped. Abdominal CT Unadjusted Stomach 25 166-2500 Ped. Abdominal CT Adjusted Stomach 6 40-600 Chest X-ray (PA/lateral) n/a Lung .01/.15 .01-.15 Screening Mammogram n/a Breast 3 20-300 The ACR estimates that modern America's annual exposure to radiation from diagnostic machines is equal to that released by a nuclear accident that spewed the equivalent of hundreds of Hiroshimas across much of Russia and Eastern Europe. In 2005, the Chernobyl Forum, an organization led by the International Atomic Energy Agency and the World Health Organization, estimated that about 6.5 million people were exposed to 5.6 Rontgen per second (R/s). This is equivalent to 20,000 Rontgen per hour (R/h). A lethal dose is around 500 Rontgen doses within several minutes of radiation from the Chernobyl explosion in 1986. Concerns about unnecessary medical radiation in young children today are now ricocheting throughout the medical community. A group of Yale researchers, looking at current patterns, estimates that in one year, 700 people will die from cancers associated with head CTs and 1,800 will die from radiation-induced cancer from abdominal examinations carried out when they were infants.(4) Reduced brain function, learning problems and lowered IQ from such potentially unnecessary and inappropriate exams is not easily calculated, but it cannot be trivial. References Amis ES, Butler PF, Applegate KE, et al. American College of Radiology White Paper on Radiation Dose in Medicine, Journal of the American College of Radiology 2007; 4:272-284. Brenner DJ, Elliston CD, Hall EJ, et al. Estimated risks of radiation-induced fatal cancer from pediatric CT. AJR Am J Roentgenol 2001; 176:289-296. Brenner DJ, Hall EJ. Computed Tomography---An Increasing Source of Radiation Exposure, The New England Journal of Medicine 2007; 357(22):2277-2282 Lee CI, Haims AH, Monico EP, Brink JA and Forman HP. Diagnostic CT Scans: Assessment of Patient, Physician, and Radiologist Awareness of Radiation Dose and Possible Risks, Radiology 2004; 231:393-398. Conflict of Interest: None declared