Radiation Exposure from Your Recent CT Scan: Risks and Measurements

CT Scan Report Radiation

The CT report you received includes several measurements related to radiation exposure during your abdominal CT scan with contrast.
The values provided are as follows:
- CTDIvol (Computed Tomography Dose Index volume): 14.00 mGy (Body)
- DLP (Dose Length Product): 449.2 mGy·cm (Body)
To estimate the total radiation dose in mGy, you can refer to the CTDIvol value, which indicates the dose per slice.
However, the total dose also depends on the number of slices acquired during the scan, which is typically not specified in the report.

Regarding cancer risk, while any exposure to ionizing radiation carries a potential risk, the risk from a single abdominal CT scan is generally considered low.
The estimated lifetime risk of developing cancer from a single abdominal CT scan is about 1 in 2,000 to 1 in 10,000, depending on various factors such as age, sex, and individual susceptibility.
If you have concerns about your health or the implications of the radiation exposure, it is advisable to discuss them with your healthcare provider, who can provide personalized guidance based on your medical history and risk factors.

Xiao Yu, 50~59 year old female. Ask Date: 2021/08/16

Dr. Wang Yifen reply Radiology

Hello, Professor Tsai Hui-Yu and colleagues have pointed out in their literature that the reference dose levels for computed tomography (CT) recommended in the EU report 16262 for general abdominal examinations have a DLP of 780 (mGy·cm).
Your report shows a value of 449.2, which is reasonable.
The two main parameters related to CT and radiation dose are CTDIvol and DLP.
DLP (Dose-Length Product) is used to assess the radiation dose received by the patient during a CT scan.
DLP (units: mGy·cm) = CTDIvol x total scan length.
E = k·DLP.
The conversion factor k (mSv·mGy⁻¹·cm⁻¹) is related to the examination site.
For a DLP of 449.2 mGy·cm, using the conversion factor k = 0.015 for adult abdomen, the effective dose E is calculated as E = 0.015 x 449.2 = 6.7 mSv.
This results in approximately 26.8 mSv when multiplied by 4.
According to the International Commission on Radiological Protection (ICRP) report 103, doses below 100 mSv (whether single or multiple) do not cause clinical functional impairment.
Following your doctor's advice to undergo radiation-related examinations is important, as the health benefits outweigh the radiation risks.
If you have concerns, it is advisable to communicate with your physician before proceeding with the examination.
Do not avoid examinations out of fear of radiation, as this may lead to missed opportunities for disease treatment.
Please consider the above information, and I wish you peace and health.
Reference: Tsai Hui-Yu et al., Recommendations for Physical Testing of X-ray Computed Tomography Systems: Report from the Computed Tomography Working Group of the Chinese Society of Medical Physics.
Chin J Radiol 2009; 34: 173-184.

Reply Date: 2021/08/16

More Info

When considering the radiation exposure from your recent abdominal CT scan, it's important to understand the measurements provided in your report, specifically CTDIvol (Computed Tomography Dose Index volume) and DLP (Dose-Length Product). These metrics help quantify the radiation dose received during the scan.

From your report, the CTDIvol values are listed as follows:
- HELICAL_CT: 14.00 mGy (BODY)
- NORMAL_CT: 9.2 mGy (BODY)
- DYNAMIC_CT: 14.4 mGy (BODY)
The DLP value is given as 449.2 mGy·cm (BODY). To calculate the effective dose in millisieverts (mSv), which is a more relevant measure for assessing cancer risk, we can use a conversion factor. For abdominal scans, this factor is typically around 0.015 mSv/mGy·cm.

Using the DLP value:
- Effective Dose (E) = DLP × Conversion Factor
- E = 449.2 mGy·cm × 0.015 mSv/mGy·cm = 6.74 mSv
This means that your abdominal CT scan likely exposed you to approximately 6.74 mSv of radiation.
Now, regarding the cancer risk associated with this level of radiation, it's essential to contextualize it. According to the International Commission on Radiological Protection (ICRP), the risk of developing cancer from radiation exposure is generally estimated to be about 1 in 10,000 for every 10 mSv of exposure. Therefore, with an exposure of approximately 6.74 mSv, the estimated increase in cancer risk would be about 1 in 15,000 to 1 in 20,000, which is relatively low.

It's also worth noting that the background radiation that everyone is exposed to naturally averages around 2-3 mSv per year, depending on geographic location. Thus, your CT scan's radiation dose is comparable to about two to three years of natural background radiation.

In terms of health impacts, while there is a theoretical risk associated with any exposure to ionizing radiation, the benefits of a medically necessary CT scan—such as diagnosing a condition or guiding treatment—often outweigh the risks. Medical professionals carefully consider these factors before recommending imaging studies.

If you have concerns about the cumulative effects of radiation from multiple scans, it's advisable to discuss these with your healthcare provider. They can provide personalized guidance based on your medical history and the necessity of the imaging studies.

In summary, while your recent CT scan does involve exposure to radiation, the dose you received is within a range that is generally considered safe, especially when the scan is clinically indicated. Always feel free to communicate your concerns with your doctor, who can help clarify the necessity of the imaging and the associated risks.

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