Is Excessive Radiation Exposure a Concern with Multiple CT Scans?

Will the radiation dose from continuous CT scans exceed safe limits?

Hello, doctor.
My father was involved in a car accident on December 4th and was taken to the emergency room at Taipei Hospital.
He sustained an injury to his leg but did not hit his head.
However, the doctor ordered a head CT scan and six X-rays of his leg.
After reviewing the CT scan and X-rays, the doctor diagnosed that all bones were normal.
On December 5th, I found my father abandoned at a bus stop by Taipei Hospital and took him back to the hospital.
When we tried to register, the nurse informed us that he was allowed to go home because the X-rays and CT scan showed no issues (although he had already been using a wheelchair during this time).
After returning home, my father experienced pain in his right knee and was unable to stand or straighten it, making it difficult for him to climb the stairs to our residence.
He was then taken to the emergency room at Fu Jen Catholic University Hospital, where the emergency physician did not accept the X-rays from Taipei Hospital (even though we had requested the disc) and ordered new X-rays.
A total of five X-rays were taken of his right knee and right calf, and the doctor informed us that he had a comminuted fracture of the right knee.
Because of the fracture, a CT scan of the knee was also required.
May I ask if the radiation dose from one day of a head CT scan (black and white), a knee CT scan (color), and 11 X-rays is too high? Thank you.

Chen Xiaobai, 40~49 year old female. Ask Date: 2023/12/06

Dr. Wang Yifen reply Radiology

Hello, diagnostic X-ray examinations are classified as low-dose radiation imaging.
According to the International Commission on Radiological Protection (ICRP) report 103, doses below 100 millisieverts (including single or multiple exposures) do not cause clinical functional damage.
The necessity of the examination should be considered for X-ray radiation checks, rather than limiting the radiation dose or the number of examinations.
Following your doctor's recommendations for radiation-related tests is important, as the health benefits outweigh the effects of radiation.
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 could lead to missed opportunities for disease treatment.
Please take this into consideration, and I wish you safety and good health.

Reply Date: 2023/12/06

More Info

Excessive radiation exposure from multiple CT scans is indeed a valid concern, particularly in the context of your father's recent medical evaluations. Understanding the risks associated with radiation exposure, especially from diagnostic imaging, is crucial for making informed decisions about healthcare.

CT scans, or computed tomography scans, use X-rays to create detailed images of the inside of the body. While they are invaluable tools for diagnosing and monitoring various medical conditions, they do expose patients to higher doses of radiation compared to standard X-rays. For instance, a single head CT scan typically delivers about 2 mSv (millisieverts) of radiation, while an abdominal CT scan can deliver around 10-14 mSv. In contrast, a standard X-ray may only expose a patient to about 0.1 mSv.

In your father's case, the combination of multiple imaging studies in a short time frame raises legitimate concerns about cumulative radiation exposure. The total radiation dose from his imaging studies can be calculated by summing the individual doses from each procedure. For example, if he underwent a head CT (2 mSv), a knee CT (approximately 10 mSv), and several X-rays (let's estimate around 0.1 mSv each for 5 X-rays, totaling 0.5 mSv), the cumulative dose could be around 12.5 mSv. This is still below the threshold of 100 mSv, which is generally considered the level at which significant health risks, including cancer, may begin to increase.

The International Commission on Radiological Protection (ICRP) suggests that doses below 100 mSv are unlikely to cause any observable health effects, although it is essential to consider that the risk is cumulative. Therefore, while a single exposure may not pose a significant risk, repeated exposures can lead to a higher overall risk over time.

It's also important to note that the medical necessity of each imaging study should be evaluated. In emergency situations, such as your father's car accident, the immediate need for accurate diagnosis often outweighs the potential risks associated with radiation exposure. However, it is always advisable to discuss the necessity of each imaging study with the healthcare provider, especially when multiple scans are being performed in a short period.

If there are concerns about radiation exposure, alternative imaging modalities such as MRI (Magnetic Resonance Imaging) or ultrasound can be considered, as they do not use ionizing radiation. However, these alternatives may not always provide the same diagnostic information as CT scans, particularly in certain clinical scenarios.

In conclusion, while your father's recent imaging studies may have resulted in a significant cumulative radiation dose, it is essential to weigh the benefits of accurate diagnosis and treatment against the potential risks of radiation exposure. Continuous communication with healthcare providers about the necessity of imaging studies and exploring alternative options when appropriate can help mitigate concerns regarding excessive radiation exposure. Always prioritize health and safety, and do not hesitate to seek a second opinion if there are lingering doubts about the appropriateness of the imaging studies being conducted.

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