Radiation Dose in Dental Cone Beam CT Scans - Dentistry

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Dear Patient,
Thank you for your inquiry regarding the radiation dose associated with dental cone beam computed tomography (CBCT) scans, particularly in the context of orthodontic evaluation. It’s understandable to have concerns about radiation exposure, especially with the varying doses reported for different types of imaging.

1) When is a "large area" dental CBCT scan used?
A large area dental CBCT scan is typically indicated in complex cases where a comprehensive view of the maxillofacial region is necessary. This includes situations such as planning for orthognathic surgery, assessing impacted teeth, evaluating the temporomandibular joint (TMJ), or when there is a need to visualize the entire dental arch and surrounding structures in detail. In orthodontics, a large area scan may be warranted if the treatment plan involves significant changes to the jaw or if there are concerns regarding the alignment of the teeth and jaw relationship that cannot be adequately assessed with standard imaging.

2) Is your orthodontic evaluation considered a "large area" scan?
For your specific case of orthodontic evaluation where the focus is on the teeth and the TMJ, it is likely that a smaller field of view (FOV) CBCT scan will suffice. Most orthodontic assessments do not require the extensive imaging that a large area scan provides. Smaller FOV scans typically focus on the dental arches and the surrounding anatomical structures, which would likely result in a lower radiation dose compared to a full jaw or large area scan.

Regarding the radiation dose, the typical effective dose for a dental CBCT scan can vary based on the machine settings and the specific area being imaged. As you mentioned, a large area scan can be around 0.6 mSv, while a smaller area scan may be as low as 0.01 mSv. In practice, most dental CBCT scans used for orthodontic purposes usually fall within the range of 0.05 to 0.2 mSv, depending on the specific protocol used and the FOV selected.

To put this into perspective, the radiation dose from a dental CBCT scan is significantly lower than that of a conventional CT scan of the abdomen, which can be around 10 mSv or more. Additionally, the radiation exposure from a dental CBCT scan is comparable to the amount of natural background radiation a person receives over a few days.

It’s important to discuss your concerns with your orthodontist or the radiologist performing the scan. They can provide insights into the necessity of the imaging and the expected radiation dose based on your specific situation. They can also explain the benefits of the scan in terms of treatment planning and outcomes, which often outweigh the risks associated with the radiation exposure.

In conclusion, while it is prudent to be aware of radiation exposure, the doses associated with dental CBCT scans are relatively low, especially when compared to other imaging modalities. Ensuring that the imaging is necessary and that the lowest possible dose is used is key to minimizing any potential risks. Always feel free to ask your healthcare provider any questions you may have regarding the procedures and their implications for your health.

Wishing you the best in your orthodontic journey!
Sincerely,
Doctor Q&A Teams