From the Guidelines
A standard brain CT scan delivers a radiation dose of approximately 3 mSv, as stated in the most recent and highest quality study 1. This dose is considered relatively low and the benefits of obtaining crucial diagnostic information typically outweigh the potential risks from radiation exposure. The actual radiation dose can vary depending on factors such as the CT scanner model, scan protocol, patient size, and whether contrast is used. Some key points to consider include:
- The radiation dose of a complete CT-based stroke imaging protocol (NCCT, multiphase CTA) ranges at approximately 8.5 mSv 1.
- Modern CT scanners often employ dose reduction techniques like iterative reconstruction algorithms and automatic exposure control to minimize radiation while maintaining image quality.
- For context, a chest X-ray delivers about 0.1 mSv, while annual background radiation exposure averages around 3 mSv.
- Healthcare providers follow the ALARA principle (As Low As Reasonably Achievable) to minimize unnecessary radiation exposure, particularly for children and pregnant women who are more sensitive to radiation effects. It's worth noting that other studies, such as 1 and 1, provide additional information on radiation exposure from CT scans, but the most recent and highest quality study 1 provides the most relevant information for this question.
From the Research
Radiation Dose of CT Scan of the Brain
- The estimated effective radiation dose (EERD) for a noncontrast head CT scan can range from 0.82 mSv to 1.65 mSv, depending on the protocol used 2.
- A low-dose CT scan protocol can minimize radiation dose while maintaining diagnostic quality, with a mean EERD of 0.82 mSv 2.
- The effective radiation dose for a CT scan of the brain can range from 0.8 to 10.5 millisievert 3.
- Reducing the tube current-time product can decrease the radiation dose, with a reduction of up to 45% possible 4.
- The radiation dose for a routine clinical adult brain CT can vary depending on the scanner used, with effective doses ranging from 1.22 to 1.86 mSv 5.
- Organ-specific radiation doses for a CT scan of the brain can vary, with the brain, eye lenses, and salivary glands receiving the highest radiation doses 4, 5.
Factors Affecting Radiation Dose
- The use of low-dose protocols can minimize radiation dose 2, 4.
- The type of scanner used can affect the radiation dose, with single-detector scanners generally having lower doses than multi-detector scanners 5.
- Reducing the tube current-time product can decrease the radiation dose 4.
- Proper positioning and shielding of the orbits can help reduce radiation dose, especially for patients who need repeated scanning and for pediatric patients 5.