Radiation Exposure: Concerns After Medical Imaging Procedures

Questions about radiation exposure?

Hello Doctor: I would like to ask you a few questions that have been troubling me for a long time and causing me concern.
I appreciate your clarification on the following situations:
In mid-July, I underwent coronary angiography (with contrast agent) with a dose of 1166, approximately 17 mSv.
In early November, I had a full-mouth X-ray due to a tooth extraction, and at the end of November, I had a CT scan from the head to the neck (with contrast agent) with a dose of about 2.5 mSv.
1.
Both imaging procedures included exposure to the thyroid gland.
Is the total radiation dose harmful to the thyroid?
2.
During the CT scan, there were two exposures: one without contrast and one with contrast.
Should the radiation dose be calculated as the sum of both exposures?
3.
Is the total radiation dose received in such a short time too high? Is there a risk of developing cancer?
4.
I have plans for pregnancy in the near future.
Is it advisable to proceed with these plans? How long should I wait before considering pregnancy?
5.
Since the CT scan of the head and neck, I have been experiencing dizziness.
Could this be caused by the CT scan?
I apologize for the many questions, and I appreciate your time in addressing my concerns.
Thank you.

Xiao Hei, 30~39 year old female. Ask Date: 2020/11/30

Dr. Wang Yifen reply Radiology

Hello, according to the International Commission on Radiological Protection (ICRP) report 103, doses below 100 millisieverts (including single or multiple exposures) do not cause clinically significant functional impairment.
The radiation examinations you mentioned will not exceed 100 millisieverts.
Following your doctor's instructions for radiation-related examinations is based on the consideration that the health benefits outweigh the radiation risks.
If you have concerns, it is advisable to communicate with your physician before undergoing the examination.
Do not avoid tests out of fear of radiation, as this may lead to missed opportunities for disease treatment.
Pregnant women who need to undergo radiation-related examinations should inform their physician and carefully evaluate whether there are alternative tests available.
Male fertility will not be affected by these imaging examinations; if there are other concerns, it is recommended to consult a urologist.
Computed tomography (CT) scans, aside from radiation side effects, do not have other adverse effects on the body.
Dizziness after the examination may be a mild adverse reaction to the contrast agent or due to other reasons.
If the dizziness is caused by the contrast agent, symptoms will improve after the medication is excreted through urine.
If the dizziness persists and does not improve, it is advisable to consult a neurologist or an otolaryngologist for evaluation of other causes.
Please take this into consideration, and I wish you safety and health.

Reply Date: 2020/11/30

More Info

Dear Patient,
Thank you for reaching out with your concerns regarding radiation exposure from recent medical imaging procedures. It's understandable to have questions about the potential risks associated with radiation, especially after undergoing multiple imaging studies. Let’s address your questions one by one.

1. Total Radiation Exposure and Thyroid Risk: You mentioned that you had a coronary angiography with a radiation dose of approximately 17 mSv, followed by a full-mouth X-ray and a CT scan of the head and neck. The cumulative radiation dose from these procedures is significant, but it's important to note that the thyroid gland is relatively sensitive to radiation. However, the risk of developing thyroid cancer from radiation exposure is generally considered low unless the doses are significantly high or if the exposure occurs during childhood. The total dose you mentioned (around 20-25 mSv) is below the threshold that is typically associated with a substantial increase in cancer risk. Nonetheless, it is always wise to discuss any specific concerns with your healthcare provider.

2. CT Scanning and Contrast: When a CT scan is performed with and without contrast, both exposures are counted separately. Therefore, if you had two scans (one with contrast and one without), you should consider the radiation dose from both scans in your total calculation. However, the actual increase in radiation exposure from the contrast agent itself is minimal compared to the radiation from the CT scan itself.

3. Cumulative Radiation Dose: The cumulative radiation dose you have received over a short period can be concerning, but it’s essential to put it into context. The International Commission on Radiological Protection (ICRP) suggests that doses below 100 mSv are unlikely to cause significant health effects, including cancer. Your total exposure, while notable, is still within a range that is generally considered safe for adults. However, if you have ongoing concerns about your cumulative exposure, it would be beneficial to discuss this with your physician, who can provide personalized advice based on your medical history and future imaging needs.

4. Family Planning and Radiation Exposure: Regarding your plans for pregnancy, it is generally recommended to wait a few months after significant radiation exposure before trying to conceive. This is to ensure that any potential effects on reproductive health are minimized. However, the doses you have received are not typically associated with a high risk of reproductive issues. It’s best to consult with your obstetrician or a fertility specialist for tailored advice based on your specific situation.

5. Post-CT Symptoms: Experiencing dizziness after a CT scan is not a common side effect directly related to radiation exposure. It could be due to various factors, including anxiety, dehydration, or even the contrast agent used during the scan. If the dizziness persists, it is crucial to follow up with your healthcare provider to rule out any other underlying issues.

In conclusion, while it is essential to be mindful of radiation exposure, the benefits of diagnostic imaging often outweigh the risks, especially when it is necessary for diagnosing or monitoring health conditions. Always feel free to discuss any concerns with your healthcare provider, who can help you weigh the risks and benefits of any proposed imaging studies.

Wishing you good health and peace of mind.

Best regards.

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