Computed Tomography (CT) scans are invaluable diagnostic Brain Scan Tools, increasingly utilized in pediatric medicine. While offering significant benefits for diagnosing illnesses and injuries in children, the potential for increased radiation exposure is a public health concern. This article explores the crucial role of CT scans as brain scan tools for children, emphasizing the importance of minimizing radiation exposure and ensuring their safe and effective use.
CT Scans as Diagnostic Brain Scan Tools
CT scans are often life-saving brain scan tools, providing detailed images essential for diagnosing various conditions in children. For individual children, when used appropriately, the benefits of CT scans significantly outweigh the small risks.
In the United States, millions of CT examinations are performed on children annually, a number that has dramatically increased since 1980. This rise is attributed to CT’s effectiveness in diagnosing common diseases and advancements in CT technology.
Despite the advantages, CT scans involve inevitable radiation exposure. Although CT scans represent a relatively small percentage of diagnostic radiological procedures, they contribute substantially to the collective radiation dose from medical x-ray examinations in the U.S. CT scans are, in fact, the largest source of medical radiation exposure for the US population.
Unique Radiation Exposure Considerations for Children Undergoing Brain Scans
Radiation exposure is a concern for everyone, but children undergoing brain scans require special consideration due to several unique factors:
- Increased Radiation Sensitivity: Children’s bodies are demonstrably more sensitive to radiation than adults, as shown in studies of exposed populations.
- Longer Lifespan: Children have a longer life expectancy, increasing the time frame for radiation damage to manifest.
- Potential for Higher Doses: If CT settings are not specifically adjusted for children’s smaller size, they may receive unnecessarily high radiation doses during brain scans.
Consequently, the risk of developing radiation-related cancer can be significantly higher for a young child compared to an adult receiving the same CT brain scan.
Advances in CT technology have led to improved image quality at lower radiation doses. Furthermore, the widespread adoption of pediatric-specific settings has reduced radiation doses for children. Higher doses are not necessary for children, and appropriate, adjusted settings should always be used during pediatric brain scans.
Repeated brain scans in a single patient pose a particular concern, regardless of dose reduction efforts. Additionally, using multiple scan phases (contrast phases) during one examination increases radiation exposure. In most cases, a single scan phase should be sufficient for pediatric CT brain scans.
Radiation Risks from CT Brain Scans in Children
Leading national and international organizations concur that there is likely no safe threshold for radiation exposure regarding cancer induction. No amount of radiation should be considered completely without risk.
The first direct study assessing cancer risk after childhood CT scans revealed a clear link between radiation dose and cancer, specifically leukemia and brain tumors. The study demonstrated that the risk of these cancers increased with higher cumulative radiation doses. A cumulative dose of 50 to 60 mGy (milligray, a unit of absorbed ionizing radiation dose) to the head was associated with a threefold increase in brain tumor risk. A similar dose to the bone marrow (where blood cells are produced) resulted in a threefold increase in leukemia risk. These risks were compared to individuals receiving less than 5 mGy to the same body regions.
The number of CT brain scans needed to reach a cumulative dose of 50-60mGy varies based on the CT scan type, patient age, and scanner settings. Using typical current settings for pediatric head CT scans, two to three scans could deliver 50-60mGy to the brain. Reaching the same dose in red bone marrow would require five to ten head CT scans, using current settings for children under 15.
Previous estimations of cancer risk from CT scans relied on risk projection models based on studies of atomic bomb survivors in Japan. The risks observed in the more recent study align with these earlier estimates.
It’s crucial to emphasize that the absolute cancer risks associated with CT brain scans are small. Lifetime cancer risks from CT scans, as estimated using models based on atomic bomb survivor data, are approximately 1 case per 1,000 people scanned, with a maximum estimated incidence of about 1 case per 500 people scanned.
The benefits of clinically justified and properly performed CT brain scans should always outweigh the risks for an individual child. However, unnecessary radiation exposure carries unnecessary risk. Minimizing radiation exposure from pediatric CT brain scans whenever possible is essential to reduce the projected number of CT-related cancers.
Immediate Strategies to Minimize Radiation Exposure During CT Brain Scans for Children
Minimizing radiation doses during CT brain scans for children is a shared responsibility among physicians, pediatric healthcare providers, CT technologists, CT manufacturers, and medical and governmental bodies. Several immediate steps can be taken:
-
Perform Only Necessary CT Brain Scans: Communication between pediatric healthcare providers and radiologists is crucial to determine the necessity of a CT brain scan and the appropriate technique. Standard guidelines for CT scans in children exist, and radiologists should review the justification for every pediatric scan and be available for consultation when uncertainty arises. When suitable, alternative modalities like ultrasound or Magnetic Resonance Imaging (MRI), which do not use ionizing radiation, should be considered.
-
Adjust Exposure Parameters for Pediatric CT Brain Scans Based On:
- Child Size: Guidelines based on individual size/weight parameters should be strictly followed.
- Region Scanned: Limit the scan area to the smallest necessary region of the brain.
- Organ Systems Scanned: Lower mA and/or kVp settings should be considered for specific brain imaging needs.
-
Scan Resolution: The highest image quality (requiring the most radiation) is not always needed for diagnosis. In many cases, lower-resolution scans are diagnostically sufficient. Providers should be familiar with dose descriptors on CT scanners and minimize multiphase examinations (multiple scans during different contrast enhancement phases). Multiphase scans significantly increase radiation dose and are rarely necessary, especially in brain imaging.
Alt Text: A young child patiently undergoing a CT brain scan in a clinical setting, highlighting the importance of pediatric-specific protocols.
Questions Parents Should Ask:
Parents naturally have concerns about their children’s radiation exposure during CT brain scans. Healthcare providers should be prepared to address questions like:
- Is a CT brain scan the most appropriate examination to diagnose my child’s condition?
- Are there alternative tests without radiation?
- Will the results impact treatment decisions?
- Will the CT brain scan be adjusted for my child’s size?
- Will the scan be performed at an accredited facility by a radiology team experienced in pediatric CT?
Studies show that providing parents with information about CT scan risks and benefits doesn’t decrease compliance but leads to more informed questions for healthcare providers. If a CT brain scan is clinically justified, parents can be reassured that the benefits outweigh the small long-term cancer risks.
Long-Term Strategies to Minimize CT Radiation
Beyond immediate steps, long-term strategies are vital to minimize CT radiation exposure in children:
- Promote the development and implementation of specific pediatric CT protocols.
- Encourage selective imaging strategies in pediatrics.
- Educate healthcare professionals through publications and conferences across specialties to optimize exposure settings and properly assess the need for CT scans in each child. Disseminate information via relevant associations, organizations, and societies involved in pediatric healthcare, such as the American Academy of Pediatrics. Provide readily accessible information sources, like the Alliance for Radiation Safety in Pediatric Imaging (Image Gently campaign).
- Support further research to determine the relationship between CT image quality and radiation dose, to personalize CT scanning for individual children, and to further clarify the link between CT radiation and cancer risk.
Conclusion
While CT scans remain indispensable brain scan tools in pediatric diagnostics, the healthcare community must collaboratively minimize radiation doses to children. Radiologists should continually strive to reduce exposure to the lowest reasonably achievable level by using child-customized settings. All physicians ordering pediatric CT scans should consistently evaluate their use on a case-by-case basis. When used judiciously and optimally, CT is among the most valuable imaging modalities for both children and adults.
Related Resources
Society for Pediatric Radiology
1891 Preston White Drive
Reston, Virginia 20191
http://www.pedrad.org
References
Amis ES, Jr., 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.
Arch ME, Frush DP. Pediatric body MDCT: A 5-year follow-up survey of scanning parameters used by pediatric radiologists. American Journal of Roentgenology 2008:191;611-617
Berrington de Gonzále. A, Mahesh M, Kim KP, Bhargavan M, Lewis R, Mettler F, Land C. Projected cancer risks from computed tomographic scans performed in the United States in 2007. Archives of Internal Medicine 2009; 169: 2071-7.
Brenner DJ, Doll R, Goodhead DT, et al. Cancer risks attributable to low doses of ionizing radiation: Assessing what we really know. Proceedings of the National Academy of Sciences of the United States of America 2003; 100:13761-13766.
Brenner DJ, Elliston CD, Hall EJ, Berdon WE. Estimated risks of radiation-induced fatal cancer from pediatric CT. American Journal of Roentgenology 2001; 176:289-296.
Brenner DJ, Hall EJ. Current concepts – Computed tomography – An increasing source of radiation exposure. New England Journal of Medicine 2007; 357:2277-2284.
Brody AS, Frush DP, Huda W, Brent RL, Radiology AAoPSo. Radiation risk to children from computed tomography. Pediatrics 2007; 120:677-682.
Cardis E, Vrijheid M, Blettner M, et al. The 15-country collaborative study of cancer risk among radiation workers in the nuclear industry: Estimates of radiation-related cancer risks. Radiation Research 2007; 167:396-416.
Chodick G, Ronckers C, Ron E, Shalev V. The utilization of pediatric computed tomography in a large Israeli Health Maintenance Organization. Pediatric Radiology 2006; 36:485-490.
Chodick G, Ronckers CM, Shalev V, Ron E. Excess lifetime cancer mortality risk attributable to radiation exposure from computed tomography examinations in children. Israel Medical Association Journal 2007; 9:584-587.
da Costa e Silva EJ, da Silva GA. Eliminating unenhanced CT when evaluating abdominal neoplasms in children. American Journal of Roentgenology 2007; 189:1211-1214.
Donnelly LF, Emery KH, Brody AS, et al. Minimizing radiation dose for pediatric body applications of single-detector helical CT: Strategies at a large children’s hospital. American Journal of Roentgenology 2001; 176:303-306.
Frush DP, Applegate K. Computed tomography and radiation: understanding the issues. Journal of the American College of Radiology 2004; 1:113-119.
Frush DP, Donnelly LF, Rosen NS. Computed tomography and radiation risks: What pediatric health care providers should know. Pediatrics 2003; 112:951-957.
Garcia Peña BM, Cook EF, Mandl KD. Selective imaging strategies for the diagnosis of appendicitis in children. Pediatrics 2004; 113:24-28.
Goske MJ, Applegate KE, Boylan J, et al. The ‘Image Gently’ campaign: increasing CT radiation dose awareness through a national education and awareness program. Pediatric Radiology 2008; 38:265-269.
Huda W, Vance A. Patient radiation doses from adult and pediatric CT. American Journal of Roentgenology 2007; 188:540-546.
Larson DB, Rader SB, Forman HP, Fenton LZ. Informing parents about CT radiation exposure in children: It’s OK to tell them. American Journal of Roentgenology 2007; 189:271-275.
McNitt-Gray MF. AAPM/RSNA physics tutorial for residents: Topics in CT – Radiation dose in CT1. Radiographics 2002; 22:1541-1553.
Mettler FA, Jr., Wiest PW, Locken JA, Kelsey CA. CT scanning: patterns of use and dose. Journal of Radiological Protection 2000; 20:353-359.
NAS. Health risks from exposure to low levels of ionizing radiation: BEIR VII phase 2. Washington D.C.: National Academy of Sciences, 2005.
NCRP. Ionizing radiation exposure of the population of the United States. NCRP Report 160. National Council on Radiation Protection and Measurements. Bethesda, Maryland, 2009.
Paterson A, Frush DP, Donnelly LF. Helical CT of the body: Are settings adjusted for pediatric patients? American Journal of Roentgenology 2001; 176:297-301.
Pearce MS, Salotti JA, Little MP, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet (published online June 7th 2012).
Pierce DA, Preston DL. Radiation-related cancer risks at low doses among atomic bomb survivors. Radiation Research 2000; 154:178-186.
Preston DL, Ron E, Tokuoka S, et al. Solid cancer incidence in atomic bomb survivors: 1958-1998. Radiation Research 2007; 168:1-64.
Rogers LF. Taking care of children: Check out the parameters used for helical CT. American Journal of Roentgenology 2001; 176:287-287.
Slovis TL. The ALARA (as low as reasonably achievable) concept in pediatric CT intelligent dose reduction. Multidisciplinary conference organized by the Society of Pediatric Radiology. August 18-19, 2001. Pediatric Radiology 2002; 32:217-317.
Strauss KJ, Goske MJ. Estimated pediatric radiation dose during CT. Pediatric Radiology 2011; 41(suppl2):S472-482.
Thomas KE, Wang BB. Age-specific effective doses for pediatric MSCT examinations at a large children’s hospital using DLP conversion coefficients: a simple estimation method. Pediatric Radiology 2008; 38:645-656.
