What is the radiation dose of a Computed Tomography (CT) scan of the neck?

From the Guidelines

The average radiation dose of a Computed Tomography (CT) scan of the neck is approximately 3 mSv, which is equivalent to about 150 chest x-rays, and is considered acceptable in the adult population. When evaluating the need for a CT scan of the neck, it is essential to consider the potential benefits and risks, including the radiation exposure. The decision to use CT or alternative imaging modalities like MRI should be based on the specific clinical scenario and patient factors. Some key points to consider when deciding on a neck CT scan include:

• The CT scan is more readily available, costs less, and is generally more easily tolerated by patients due to shorter scanning times and larger scanner bores 1.
• MRI offers improved tissue contrast and can help detect subclinical tumors, but it may be limited by motion artifact and longer scan times, and is preferred when a primary tumor of the nasopharynx is suspected or when there is cranial nerve abnormality on physical examination 1.
• The presence of some implantable medical devices precludes MRI scanning, making CT a more suitable option in these cases 1.
• Modern CT scanners often use dose reduction techniques to minimize radiation while maintaining diagnostic image quality.
• The radiation risk from a single neck CT is generally considered low for most adults, but children and pregnant women are more sensitive to radiation effects, so extra consideration is given in these populations. It is crucial to discuss the necessity of the CT scan and potential alternative imaging methods with a healthcare provider, considering the specific condition and individual patient factors 1.

From the Research

Radiation Dose of CT Scan of the Neck

• The radiation dose of a Computed Tomography (CT) scan of the neck can vary depending on the scanner and protocol used 2, 3, 4, 5, 6.
• A study published in the Polish journal of radiology in 2019 found that the minimum and maximum volumetric CT dose index (CTDIv) for a neck scan were 16 ± 2 to 27 ± 3 mGy, and the dose length product (DLP) was 286 ± 127 to 645 ± 79 mGy × cm 2.
• The same study found that the effective dose (ED) for a neck scan ranged from 1.46 ± 0.65 to 3.29 ± 0.40 mSv 2.
• Another study published in Diagnostic and interventional radiology in 2021 found that the median CTDIv value for a neck CT scan was 13.1 mGy, and the median DLP value was 299 mGy.cm 6.
• The median effective dose (ED) value for a neck CT scan was found to be 1.76 mSv 6.
• Reducing overscan frequency and scan length can help optimize radiation dose in neck CT scans, with one study finding a 20% reduction in overall radiation dose after targeted educational talks 5.

Factors Affecting Radiation Dose

• The type of scanner used can affect the radiation dose, with newer scanners tend to have lower doses 2, 4.
• The protocol used can also affect the radiation dose, with some protocols resulting in lower doses than others 3, 4.
• Patient factors, such as body mass index (BMI), can also affect the radiation dose, with higher BMIs requiring higher doses 3, 4.

Comparison with Diagnostic Reference Levels

• The radiation dose parameters for neck CT scans can vary compared to diagnostic reference levels (DRLs), with some studies finding higher or lower doses than the DRLs 6.