Medical imaging, such as X-rays and CT scans, plays a vital role in diagnosing common health problems like fractures, infections, heart disease, tooth decay, and even cancer. These tools are often life-saving and generally considered safe. But with their growing use, especially in hospital settings, experts are raising concerns about the long-term effects of repeated exposure to ionising radiation.
Understanding radiation exposure
According to Harvard Health Publishing, we are naturally exposed to radiation from our environment- about 3 millisieverts (mSv) per year. Imaging tests add to this background radiation in varying amounts:
Bone density test: 0.001 mSv
Dental X-ray: 0.005 mSv
Chest X-ray: 0.1 mSv
The amount of radiation is higher with CT 9 Computed Tomography), especially if it's done with contrast dye. Dr Mark Hammer, a radiologist at Harvard-affiliated Brigham and Women's Hospital, said, "For example, a chest CT scan without contrast dye emits 4 mSv, whereas one with contrast dye emits 6 mSv."
Abdominal and pelvic CT scans with contrast dye emit up to 16 mSv.
Is there a risk?
Ionising radiation has the potential to damage body tissues, including DNA within cells. While standard X-rays carry very low cancer risk, CT scans, which deliver significantly more radiation, have raised more serious concerns.
A 2009 study suggested that CT scans could contribute to 2% of all annual cancer cases in the US. That estimate increased in a 2025 study published in JAMA Internal Medicine, which projected that 103,000 future cancers could arise from the 93 million CT scans performed in 2023 alone. If those numbers prove accurate, CT-related cancers could eventually account for 5% of all annual cancer diagnoses.
It's important to note, however, that both studies were based on simulations, and most of what we know about long-term radiation risk comes from research on atomic bomb survivors, people exposed to much higher doses than typical medical imaging provides.
Why the increase in CT scans?
The rise in CT-related risk doesn't stem from new dangers; it's due to more frequent use of the technology. According to Dr Mark Hammer, a radiologist at Brigham and Women's Hospital:
"CT has the same risk we've known about. But more patients are getting more scans nowadays, and that could lead to additional cancer cases."
There are two main reasons for this trend:
Cancer patients are living longer, meaning they require more imaging for long-term monitoring.
Emergency departments (EDs) are using CT more frequently, often to speed up diagnosis. Additionally, non-physician providers in EDs tend to order more imaging compared to doctors.
What you can do
Imaging tests offer immense benefits. They can detect problems early, guide treatments, and, in many cases, save lives. But unnecessary scans can increase long-term risks.
Here are a few smart steps to protect yourself:
Ask questions: If your doctor recommends a CT scan, ask what the test will show, whether it will change your treatment, and if it's truly necessary.
Mention recent scans: Share your medical imaging history—especially in emergency settings, where staff may not have full access to your records.
Request alternatives: Ask whether safer options like MRI or ultrasound, which don't use ionising radiation, might be suitable.
Discuss radiation dose: If a CT scan is essential, inquire whether the radiation dose can be minimised.
Dr Hammer puts it clearly, "The key question is whether CT is truly necessary. If it is, then the benefits will outweigh the tiny increased risk of cancer. But if guidelines suggest no imaging is needed, then the risk probably outweighs any benefit."
The bottom line
Imaging is a powerful tool in modern medicine, but like any tool, it should be used wisely. Stay informed, ask the right questions, and work with your healthcare providers to make the best decisions for your health.
Comments