Calculating the exact radiation dose from a CT (computed tomography) scan can be a bit complex and depends on various factors such as the specific CT scanner used, scan parameters, and the region being scanned. However, I can provide you with some general information.
The radiation dose from a CT scan is typically measured in terms of DLP (Dose-Length Product) in units of mGy-cm (milligray-centimeters). DLP represents the total amount of radiation delivered to the scanned tissue during the CT examination.
To convert DLP to effective dose (in mSv), a conversion factor known as the "k-factor" is used. The k-factor depends on the specific body region scanned (e.g., head, chest, abdomen) and is provided by regulatory bodies or can be estimated based on the type of CT scan.
For head CT scans, the typical k-factor is approximately 0.002 mSv/mGy-cm.
Now, let's calculate the effective dose from the given DLP of 1068 mGy-cm for the head CT scan:
Effective Dose (in mSv) = DLP (in mGy-cm) × k-factor (for head CT)
Effective Dose (in mSv) = 1068 mGy-cm × 0.002 mSv/mGy-cm ≈ 2.136 mSv
So, based on the provided DLP value and the k-factor for head CT scans, the effective dose is approximately 2.136 mSv. The value you obtained from the online calculator (2.243 mSv) may have some slight differences due to variations in k-factors used in different sources or rounding errors.
It's essential to note that radiation doses from medical imaging should be carefully considered by healthcare professionals, and they are typically justified based on the medical necessity of the scan and the benefits outweighing the potential risks. If you have concerns about the radiation dose you received during a CT scan, it's best to discuss it with your healthcare provider or radiologist. They can provide you with more personalized information and address any specific concerns you may have.