Feature | June 08, 2012

Childhood CT Scans Linked to Leukemia, Brain Cancer Later in Life

June 8, 2012 — Children and young adults scanned multiple times by computed tomography (CT) have a small increased risk of leukemia and brain tumors in the decade following their first scan. These findings are from a study of more than 175,000 children and young adults that was led by researchers at the National Cancer Institute (NCI), part of the National Institutes of Health, and at the Institute of Health and Society, Newcastle University, England.

The researchers emphasize that when a child suffers a major head injury or develops a life-threatening illness, the benefits of clinically appropriate CT scans should outweigh future cancer risks. The results of the study were published online June 7 in The Lancet.

"This cohort study provides the first direct evidence of a link between exposure to radiation from CT and cancer risk in children," said senior investigator Amy Berrington de González, Ph.D., division of cancer epidemiology and genetics, NCI. "Ours is the first population-based study to capture data on every CT scan to an individual during childhood or young adulthood, and then measure the subsequent cancer risk."

Despite the elevation in cancer risk, these two malignancies are relatively rare and the actual number of additional cases caused by radiation exposure from CT scans is small. The most recent (2009) U.S. annual cancer incidence rates for children from birth through age 21 for leukemia and brain and other nervous system cancers are 4.3 per 100,000 and 2.9 per 100,000, respectively. The investigators estimate that for every 10,000 head CT scans performed on children 10 years of age or younger, one case of leukemia and one brain tumor would occur in the decade following the first CT beyond what would have been expected had no CT scans been performed.

CT scans deliver a dose of ionizing radiation to the body part being scanned and to nearby tissues. Even at relatively low doses, ionizing radiation can break the chemical bonds in DNA, causing damage to genes that may increase a person’s risk of developing cancer. Children typically face a higher risk of cancer from ionizing radiation exposure than do adults exposed to similar doses.

The investigators obtained CT examination records from radiology departments in hospitals across Britain and linked them to data on cancer diagnoses and deaths. The study included people who underwent CT scans at British National Health Service hospitals from birth to 22 years of age between 1985 and 2002. Information on cancer incidence and mortality from 1985 through 2008 was obtained from the National Health Service Central Registry, a national database of cancer registrations, deaths and emigrations.

Approximately 60 percent of the CT scans were of the head, with similar proportions in males and females. The investigators estimated cumulative doses from the CT scans received by each patient, and assessed the subsequent cancer risk for an average of 10 years after the first CT. The researchers found a clear relationship between the increase in cancer risk and increasing cumulative dose of radiation. A three-fold increase in the risk of brain tumors appeared following a cumulative absorbed dose to the head of 50 to 60 mGy (unit of estimated absorbed dose of ionizing radiation). Similarly, a three-fold increase in the risk of leukemia appeared after the same dose to bone marrow. The comparison group consisted of individuals who had cumulative doses of less than 5 mGy to the relevant regions of the body.

The absorbed dose from a CT scan depends on factors including age at exposure, sex, examination type, and year of scan. Broadly speaking, two or three CT scans of the head using current scanner settings would be required to yield a dose of 50 to 60 mGy to the brain. The same dose to bone marrow would be produced by five to 10 head CT scans, using current scanner settings for children under age 15.

In countries like the United States and Britain, the use of CT scans in children and adults has increased rapidly since their introduction 30 years ago. Due to efforts by medical societies, government regulators, and CT manufacturers, scans performed on young children in 2012 can have 50 percent lower radiation doses, compared to scans carried out in the 1980s and 1990s, say the investigators. However, the amount of radiation delivered during a single CT scan can still vary greatly and is often up to 10 times higher than that delivered in a conventional X-ray procedure.

“CT can be highly beneficial for early diagnosis, for clinical decision-making and for saving lives. However, greater efforts should be made to ensure clinical justification and to keep doses as low as reasonably achievable,” said Mark S. Pearce, Ph.D., Institute of Health and Society, Newcastle University, lead author of the study.

For more information: www.cancer.gov/cancertopics/causes/radiation/radiation-risks-pediatric-CT

Related Content

Hospital for Special Surgery Invests in Sectra Orthopedic 3-D Planning Software
News | Orthopedic Imaging | January 18, 2018
January 18, 2018 – International medical imaging IT and cybersecurity company Sectra announces that Hospital for Spec
Philips Introduces Technology Maximizer Program for Imaging Equipment Upgrades
Technology | Imaging | January 17, 2018
January 17, 2018 — Philips recently announced the launch of Technology Maximizer, a cross-modality program designed t
Transpara Deep Learning Software Matches Experienced Radiologists in Mammogram Reading
News | Computer-Aided Detection Software | January 12, 2018
Deep learning and artificial intelligence improves the efficiency and accuracy of reading mammograms, according to...
Smartphone Addiction Creates Imbalance in Brain
News | Mobile Devices | January 11, 2018
Researchers have found an imbalance in the brain chemistry of young people addicted to smartphones and the internet,...
Fat Distribution in Women and Men Provides Clues to Heart Attack Risk
News | Women's Health | January 11, 2018
January 11, 2018 – It’s not the amount of fat in your body but where it is stored that may increase your risk for hea
Emergency Radiologists See Inner Toll of Opioid Use Disorders

Rates of Imaging Positivity for IV-SUDs Complications. Image courtesy of Efren J. Flores, M.D.

News | Clinical Study | January 11, 2018
January 11, 2018 – Emergency radiologists are seeing a high prevalence of patients with complications related to opio
Minimally Invasive Treatment Provides Relief from Back Pain

Lumbar spine MRI showing disc herniation and nerve root at baseline and one month after treatment

News | Interventional Radiology | January 11, 2018
The majority of patients were pain free after receiving a new image-guided pulsed radiofrequency treatment for low back...
Study Finds No Evidence that Gadolinium Causes Neurologic Harm

MR images through, A, C, E, basal ganglia and, B, D, F, posterior fossa at level of dentate nucleus. Images are shown for, A, B, control group patient 4, and the, C, D, first and, E, F, last examinations performed in contrast group patient 13. Regions of interest used in quantification of signal intensity are shown as dashed lines for globus pallidus (green), thalamus (blue), dentate nucleus (yellow), and pons (red).

News | Contrast Media | January 11, 2018
January 11, 2018 — There is no evidence that accumulation in the brain of the element gadolinium speeds cognitive dec
CT Shows Enlarged Aortas in Former Pro Football Players

3-D rendering from a cardiac CT dataset demonstrating mild dilation of the ascending aorta.

News | Computed Tomography (CT) | January 11, 2018
Former National Football League (NFL) players are more likely to have enlarged aortas, a condition that may put them at...

Size comparison between 3-D printed prosthesis implant and a penny.

News | 3-D Printing | January 11, 2018
January 11, 2018 — Researchers using...
Overlay Init