What is the repeated spine Computed Tomography (CT) scan radiation dose?

From the Guidelines

Repeated spine CT scans should be limited due to cumulative radiation exposure, with a typical spine CT delivering approximately 10 mSv of radiation per scan, as estimated by recent studies 1. The radiation dose from repeated spine CT scans is a significant concern, as it can increase the risk of cancer and other harmful effects. According to the American College of Radiology white paper on radiation dose in medicine 1, the estimated radiation dose from a single CT scan can range from 10 to 25 mSv, and some patients may have multiple studies, exceeding the 50 mSv threshold associated with an increased risk of cancer. Key considerations for minimizing radiation exposure include:

• Using MRI as a preferred alternative when available, as it uses no ionizing radiation
• Spacing CT scans appropriately and following the ALARA principle (As Low As Reasonably Achievable)
• Utilizing modern CT scanners with dose reduction technologies that can decrease radiation by 30-50% while maintaining diagnostic quality
• Creating an imaging schedule that balances diagnostic needs with radiation exposure concerns, particularly for patients with chronic spine conditions requiring regular monitoring
• Being cautious with repeated CT scans in children and young adults, as they are more sensitive to radiation effects and have more years ahead for potential radiation-related complications to develop. The benefit of accurate diagnosis and treatment guidance from CT scans must be weighed against the small but real long-term risk of radiation exposure, as noted in the study 1.

From the Research

Repeated Spine Computed Tomography (CT) Scan Radiation Dose

• The radiation dose from repeated spine CT scans is a concern due to the potential risk of secondary malignancies 2.
• A study found that low-dose lumbar spine CT at about 1 mSv has superior image quality to lumbar spine radiography with more anatomical and diagnostic information 3.
• The effective dose for low-dose CT was 1.0-1.1 mSv, which is higher than the dose used in conventional radiographic examinations but still 10 to 100 times lower than the dose levels that have been reported to increase the risk of cancer 4.
• To reduce radiation exposure in postoperative spinal CT scans, it is recommended to direct the scan only through the area of specific interest and limit the total dose of radiation received by the patient 5.
• A survey found that a relatively low percentage of patients (0.5%) received a cumulative effective dose from CT examinations equal to or greater than 100 mSv, with most of them having an oncological disease 6.
• Measures to lower the cumulative effective dose include using procedures that do not necessitate radiation, using very low-dose procedures, being critical in requiring imaging procedures, and increasing awareness about the issue 6.

Factors Affecting Radiation Dose

• The risk for damaging DNA and developing cancer increases with increasing scan length and amount of radiation received 5.
• Local practice, institution, and medical focus can be significant factors in the levels of cumulative effective dose received 6.
• Patients with cancer, chronic diseases, and trauma run the highest risk of having a high cumulative effective dose 6.

Strategies for Reduction

• Technical developments in CT acquisition and reconstruction must include efforts to reduce the radiation dose 2.
• The use of dose management and clinical decision support systems can help refine or improve practice where recurrent examinations are required 6.
• Increasing awareness of referring physicians through encouraging local dialogue and concrete actions focused on optimization can help reduce radiation exposure 6.