From the Guidelines
Frequent CT scans pose significant radiation exposure risks that should be minimized whenever possible to reduce the risk of cancer and other harmful effects. The primary concern is cumulative radiation exposure, which can increase cancer risk over time, particularly for radiosensitive organs like the thyroid, breast, and gonads 1. A single abdominal CT scan delivers approximately 10 mSv of radiation, equivalent to about three years of background radiation. To mitigate these risks, healthcare providers should follow the ALARA principle (As Low As Reasonably Achievable) by considering alternative imaging modalities like ultrasound or MRI when appropriate, as these don't use ionizing radiation 1. When CT scans are necessary, using dose reduction techniques such as limiting the scan area, adjusting parameters based on patient size, and employing iterative reconstruction algorithms can significantly reduce radiation exposure 1.
Some key strategies to minimize risks include:
- Maintaining a record of imaging history and discussing the necessity of each scan with the provider to ensure diagnostic benefit outweighs radiation risk
- Considering alternative imaging modalities for patients, especially children and pregnant women, who are more vulnerable to radiation effects
- Spacing out CT scans when medically appropriate and using the lowest dose protocols that still provide diagnostic quality images
- Following guidelines such as those from the American College of Radiology (ACR) for performing low radiation dose chest CT scans 1
It's also important to note that the risk of radiation-induced malignancy from CT scans is small but real, and approximately 0.4% of all cancers in the United States may be attributable to the radiation from CT studies 1. Therefore, a careful balance between the benefits of CT scans for diagnostic purposes and the potential risks associated with radiation exposure must be considered in clinical practice.
From the Research
Risks of Frequent CT Scans
- The risks associated with frequent Computed Tomography (CT) scans include an increased risk of cancer due to radiation exposure 2, 3, 4, 5.
- The radiation exposure from CT scans can cause stochastic and deterministic effects, with the additional individual relative lifetime cancer mortality risk estimated at 5% per sievert 3.
- Frequent CT scanning, particularly in young adults, can lead to a significant cancer risk, although this risk is often outweighed by the benefits of the scan in severely ill patients 4.
- Studies have shown that exposure to medical radiation from CT scans is associated with an elevated risk of thyroid cancer, leukemia, and non-Hodgkin lymphoma (NHL) in adults, particularly in women and younger patients 5.
Mitigating the Risks of CT Scans
- Technical advances, targeted dose monitoring, and analyses of dose data can help identify areas where improvement is necessary to lower patients' radiation exposure while preserving adequate image quality 3.
- The use of alternative imaging modalities, such as ultrasound or magnetic resonance imaging (MRI), can reduce the need for CT scans and minimize radiation exposure.
- Implementing protocols to minimize radiation exposure, such as using lower dose settings and reducing the number of scans, can also help mitigate the risks associated with CT scans.
Cancer Risk and CT Scans
- The evidence suggests that exposure to multiple CT scans with a cumulative dose up to 100 mSv (approximately 10 scans), and possibly as high as 200 mSv (approximately 20 scans), does not increase cancer risk 6.
- However, other studies have found a clear dose-response relationship between CT scans and cancer risk, particularly in patients aged 45 years or younger 5.
- The methodologic quality of studies examining the relationship between low-dose radiation and cancer has been evaluated, with a preponderance of higher-quality studies finding no increased risk of cancer from low-dose radiation 6.