Background: Various reports support the use of cervical spine (c-spine) CT over conventional radiography in screening of c-spine injury. Interest now exists in diagnostic radiation-induced morbidity.
Objective: To estimate excess relative risk for developing cancer from c-spine high-resolution CT radiation exposure.
Materials and methods: We conducted a retrospective review of children evaluated for c-spine injury using CT. The study population was divided into three age groups, 0-4 years (group 1), 5-8 years (group 2), and older than 8 years (group 3). Anthropomorphic 1-year-old and 5-year-old phantoms were used to measure radiation at the thyroid during radiography and CT. Excess relative risk for thyroid cancer was estimated using these measurements.
Results: A total of 557 patients were evaluated with CT. The radiographic method most commonly used was head CT/c-spine CT in 363 (65%). Only 179 children (32%) had any type of prior radiography. The use of c-spine CT exposes the thyroid to 90-200 times more radiation than multiple conventional radiographs. The mean excess relative risk for thyroid cancer after CT was 2.0 for group 1 and 0.6 for group 2. There were no comparison data for group 3.
Conclusion: C-spine CT is associated with a significant exposure to ionizing radiation and increases excess relative risk for thyroid cancer in young children.