Computed Tomography (CT) scans are a vital diagnostic tool in modern medicine, offering detailed images that can be life-saving, especially for children. However, the increasing use of pediatric CT scans raises concerns about radiation exposure in young patients. This article aims to explore the benefits of CT scans for children while emphasizing the importance of minimizing radiation risks. We will delve into the following key areas:
- The role of CT scans in pediatric diagnosis
- Specific vulnerabilities of children to radiation
- Potential radiation risks associated with CT scans in children
- Practical strategies to reduce radiation exposure during pediatric CT scans
CT Scans: A Powerful Diagnostic Tool for Children
CT scans are indispensable for diagnosing a wide range of illnesses and injuries in children. For an individual child needing a diagnosis, the benefits of a CT scan when appropriately used significantly outweigh the small risks involved.
In the United States, pediatric CT scans are frequently performed, with approximately 5 to 9 million examinations conducted annually. Since 1980, the utilization of CT scans in both adults and children has increased dramatically, growing roughly tenfold, with an estimated annual growth rate of about 10 percent. This surge is largely attributed to CT’s effectiveness in diagnosing common conditions and advancements in CT technology.
Despite the numerous advantages of CT scans, they inherently involve radiation exposure. While CT scans account for about 12 percent of all diagnostic radiology procedures in major U.S. hospitals, they are responsible for approximately 49 percent of the collective radiation dose received by the U.S. population from medical X-ray examinations. This makes CT scans the most significant contributor to medical radiation exposure in the United States.
Unique Radiation Sensitivity in Children
Radiation exposure is a concern for everyone, but children present unique considerations that heighten these concerns:
- Increased Radiation Sensitivity: Children’s bodies are demonstrably more susceptible to radiation than adults. Epidemiological studies of exposed populations confirm this heightened sensitivity.
- Longer Lifespan: Children have a considerably longer life expectancy than adults. This extended lifespan provides a larger window for potential radiation-induced damage to manifest as health issues later in life.
- Potential for Overexposure: Children may receive unnecessarily high radiation doses if CT scan settings are not specifically adjusted for their smaller body size.
These factors combined mean that the risk of developing radiation-related cancer can be several times greater for a young child compared to an adult receiving the same CT scan.
Over the past decade, advancements in CT technology have led to improved image quality at lower radiation doses. The widespread adoption of pediatric-specific settings has also significantly reduced radiation doses for children. It’s crucial to understand that higher radiation doses are unnecessary for children, and appropriate, child-adjusted settings should always be employed.
However, repeated CT scans in a single patient are particularly concerning, regardless of dose reduction efforts. Furthermore, using multiple scans (different contrast “phases”) during a single examination will further increase radiation exposure. In the majority of pediatric CT cases, a single, well-optimized scan should be sufficient.
Understanding Radiation Risks from Pediatric CT Scans
Leading national and international organizations that assess radiation risks generally agree that there is likely no absolutely “safe” threshold for low-dose radiation in terms of cancer induction. In other words, any radiation exposure carries some level of risk.
The first study to directly evaluate cancer risk following CT scans in childhood revealed a clear dose-response relationship for leukemia and brain tumors. The study found that the risk of these cancers increased with higher cumulative radiation doses. For a cumulative radiation dose of 50 to 60 milligray (mGy) to the head, the risk of brain tumors was reported to be three times higher. Similarly, the same dose to the bone marrow (where blood cells are produced) resulted in a threefold increase in leukemia risk. These risks were compared to a group that received cumulative doses of less than 5 mGy to the relevant body regions.
The number of CT scans needed to reach a cumulative dose of 50-60mGy varies depending on the type of CT scan, the child’s age, and the scanner settings. Using typical current settings for a head CT scan in children, a dose of 50-60mGy to the brain would be reached after just two to three head CT scans. For red bone marrow, the same dose would be reached after approximately five to 10 head CT scans using current pediatric settings for children under 15.
Previous estimations of potential cancer risks from CT scans were based on risk projection models derived mainly from studies of atomic bomb survivors in Japan. The risks observed in the more recent childhood CT scan study align with these earlier estimations.
It is important to emphasize that the absolute cancer risks associated with CT scans are still small. Lifetime cancer risks from CT scans, estimated using projection models based on atomic bomb survivor data, are approximately 1 case of cancer for every 1,000 people scanned, with a maximum estimated incidence of about 1 case per 500 people scanned.
For each child, the benefits of clinically necessary and properly performed CT scans should always outweigh the potential risks. However, unnecessary radiation exposure always carries unnecessary risk. Minimizing radiation exposure from pediatric CT scans whenever possible is crucial to reducing the projected number of CT-related cancers.
Immediate Steps to Minimize CT Radiation Exposure in Children
Minimizing radiation doses to children during CT scans is a shared responsibility among physicians, pediatric healthcare providers, CT technologists, CT manufacturers, and medical and governmental organizations. Several immediate measures can be implemented:
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Justify Every CT Scan: Careful communication between pediatric healthcare providers and radiologists is essential to determine the necessity of a CT scan and the most appropriate technique. Standard guidelines for CT scans in children exist, and radiologists should review the clinical reasons for every pediatric scan and be available for consultation when the need for a CT is uncertain. When clinically appropriate, alternative imaging methods that do not use ionizing radiation, such as ultrasound or Magnetic Resonance Imaging (MRI), should be considered.
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Optimize Exposure Parameters for Pediatric CT:
- Child Size Adjustment: CT settings should be adjusted based on the individual child’s size and weight. Specific guidelines based on these parameters should be strictly followed.
- Limit Scan Region: The area of the body scanned should be limited to the smallest region necessary to obtain the required diagnostic information.
- Organ-Specific Settings: Lower milliampere (mA) and/or kilovoltage peak (kVp) settings should be considered for imaging skeletal structures, lungs, and in certain CT angiography and follow-up examinations.
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Adjust Scan Resolution: The highest image quality (which requires the most radiation) is not always necessary for accurate diagnoses. In many cases, lower-resolution scans are sufficient and deliver less radiation. Healthcare providers should be familiar with the dose descriptors available on CT scanners and minimize the use of multiphase CT examinations. These examinations, involving multiple scans during different contrast enhancement phases, significantly increase radiation dose and are rarely necessary, especially for body (chest and abdomen) imaging.
Questions Parents Should Ask:
Parents naturally have concerns about their children’s radiation exposure during CT scans. Healthcare providers should be prepared to address questions like:
- Is a CT scan the most appropriate test to diagnose my child’s condition?
- Are there alternative tests that do not involve radiation?
- Will the CT scan results change my child’s treatment plan?
- Will the CT scan be adjusted for my child’s size?
- Will the CT scan be performed at an accredited facility by a radiology team experienced in pediatric CT?
Studies have shown that providing parents with information about the risks and benefits of CT scans does not decrease compliance but does lead to more informed questions for healthcare providers.
When a CT scan is clinically justified, parents can be reassured that the benefits outweigh the small long-term cancer risks associated with the procedure.
Long-Term Strategies for Radiation Reduction
Beyond immediate measures, long-term strategies are crucial to continually minimize CT radiation exposure in children:
- Promote the development and widespread adoption of standardized pediatric CT protocols.
- Encourage the use of selective imaging strategies in pediatrics, such as for pre-surgical appendicitis evaluations.
- Enhance education within and outside radiology through publications and conferences to optimize exposure settings and ensure appropriate CT utilization. Disseminate information via relevant associations, organizations, and societies involved in children’s healthcare, such as the American Academy of Pediatrics and the American College of Emergency Physicians. Provide easily accessible information resources like the Alliance for Radiation Safety in Pediatric Imaging.
- Support ongoing research to better understand the relationship between CT image quality and radiation dose, to personalize CT scanning for individual children, and to further clarify the correlation between CT radiation and cancer risk.
Conclusion
CT scans are an invaluable tool in pediatric medicine, but it is imperative for the healthcare community to collaborate in minimizing radiation doses to children. Radiologists must consistently strive to reduce exposure to levels “as low as reasonably achievable” (ALARA) by using child-specific exposure settings. All physicians ordering pediatric CT scans should continually evaluate the necessity of each scan on a case-by-case basis. When used judiciously and optimally, CT scans remain one of the most beneficial imaging modalities for both children and adults.
Related Resources
Society for Pediatric Radiology
1891 Preston White Drive
Reston, Virginia 20191
http://www.pedrad.org
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