Risks of CT Scans

CT scans are a powerful diagnostic tool, but it’s natural to be concerned about the associated risks. Whether it’s a brain CT scan to detect a potential tumor or a full-body computed tomography scan, the side effects of radiation exposure should be carefully considered.

Repeated scans increase radiation exposure, which could lead to long-term health issues. Children are particularly vulnerable to CT scan risks, as their bodies are more sensitive to radiation.

While the benefits of a CT scan often outweigh the risks, it’s important to stay informed and work with your healthcare provider to minimize unnecessary exposure.

The main risk of CT scans is exposure to ionizing radiation, which can damage cells and potentially lead to tumor development. Although the radiation dose with each CT scan procedure is generally low and considered safe, the risk increases with repeated exposure over time.

It is crucial to inform healthcare providers about any previous CT scans, especially when seeing a new doctor.

Children are at greater risk from radiation exposure because their bodies are more sensitive, generally.  Given that children also have a longer expected lifespan, radiation-induced health issues, such as cancer, might develop.

By keeping track of your CT scan history and discussing it with your healthcare provider, you can help minimize unnecessary exposure to radiation.

Some CT scans require the use of contrast material to enhance the visibility of certain areas of the body. Contrast is often used to aid in the diagnosis of brain aneurysms and other vascular abnormalities.

Contrast agents, usually iodine-based, can sometimes cause allergic reactions ranging from mild itching to severe anaphylaxis (swelling of the airway, possibly fatal heart dysrhythmias).

Depending on the severity of the allergic reaction, the symptoms may resolve on their own or may require emergency medical intervention. Certain individuals may have higher risk of an allergic reaction to contrast material.

Patients with a previous history of reactions to contrast dye, history of allergies to iodine or seafood, those with asthma, or other allergic conditions, should inform their healthcare provider.

For patients with a history of moderate or severe reactions to contrast material, premedication is often recommended. Premedication typically consists of steroids and antihistamines administered in the 24-48 hours prior to a scheduled imaging test. 

The use of contrast dye in CT scans can have effects on kidney function, particularly in individuals with pre-existing kidney conditions or other risk factors. The primary concern is the development of contrast-induced nephropathy, which is an acute deterioration in renal function following the administration of iodinated contrast material.

To reduce the risk of kidney damage, your healthcare team may recommend increased hydration before contrast dye administration, use of less damaging contrast dye, using less contrast dye, or using alternative imaging, such as MRI or ultrasound.

It is important to inform your team of any history of kidney issues prior to undergoing a CT scan with contrast dye. The care team may want to screen your kidney function with a blood test prior to any contrast administration. 

CT scans are rarely used for pregnant patients, as ionizing radiation can be harmful to a developing fetus. Your care team will likely consider the following: 

• Alternative imaging methods, such as MRI and ultrasound, are typically recommended first. 
• If a CT scan is deemed necessary for the patient’s health and critical diagnostic information is required, it may still be performed with caution.
• In such cases, special precautions are taken:
  • The abdomen will be shielded to protect the fetus.
  • The lowest possible radiation dose will be used while maintaining image clarity.

Some patients may experience anxiety or claustrophobia during a CT scan, as the procedure involves lying still while moving through a narrow tube. It is important to speak with your medical team if you have had a history of anxiety and/or claustrophobia.

Although it is one of the less severe risks associated with undergoing a CT scan, your healthcare provider can work with you to help make the experience more comfortable.

While CT scans are a powerful diagnostic tool, they are not perfect. The interpretation of computed tomography scan images can be challenging:

• False Positive: When a condition appears to be present, but is not. 
• False Negative: When a condition appears to be absent, but is present. 
• Incidental finding: Observations noted on a CT scan that are unrelated to the original diagnostic question. Incidental findings can range from benign and clinically insignificant, to potentially serious conditions that require further investigation.

If any of these issues occur, your physician will discuss them with you along with next steps.

• CT scans use ionizing radiation, which can damage healthy cells with excessive exposure.
• Contrast dye improves image quality but may cause allergic reactions and can reduce kidney function in those with kidney disease.
• Pregnant patients should inform their physician due to the risk of radiation exposure to the fetus.
• The enclosed space of a CT scanner can trigger anxiety or claustrophobia in some patients, which can be managed.
• Despite potential risks, CT scans are highly effective diagnostic tools for neurological and other conditions.

• United States Food & Drug Administration (FDA): CT Scan Risks
• National Institute of Biomedical Imaging and Bioengineering (NIBIB): CT Scan
• American Association of Neurological Surgeons (AANS): Cerebrovascular Imaging
• National Health Service (NHS) [UK]: CT Scan