CT scans are considered “radioactive” because they use ionizing radiation—specifically X-rays—to create detailed images of the inside of the body. This ionizing radiation has enough energy to remove tightly bound electrons from atoms, which can cause changes in cells and tissues. The amount of radiation used in a CT scan is significantly higher than that in a standard X-ray because CT imaging requires multiple X-ray images taken from different angles to produce cross-sectional views, which are then combined to form a detailed 3D picture.
The reason CT scans involve higher radiation doses compared to other imaging methods lies in their complexity and the need for high-resolution images. Unlike a simple X-ray that captures a single flat image, a CT scan rotates around the patient, capturing numerous slices of the body. Each slice requires a burst of X-rays, and when combined, these bursts add up to a larger total radiation dose. This dose is measured in milligrays (mGy), and while a single CT scan typically delivers doses in the range of tens of mGy, this is still much higher than a conventional X-ray.
The ionizing radiation in CT scans can damage DNA and cells, which is why there is concern about the potential increased risk of cancer from repeated or unnecessary scans. The risk is generally low for a single scan but can accumulate with multiple exposures. Younger patients and women tend to be more sensitive to radiation, making the risk slightly higher for these groups. The risk also depends on the part of the body scanned, as some organs are more radiosensitive than others.
Despite these risks, CT scans are invaluable diagnostic tools that can detect diseases, injuries, and abnormalities that other imaging techniques might miss. Medical professionals carefully weigh the benefits against the risks before recommending a CT scan. Advances in technology and protocols aim to minimize radiation doses while maintaining image quality, such as using dose modulation techniques and limiting scans to the necessary area.
In summary, CT scans are “radioactive” because they use ionizing X-ray radiation at doses higher than standard X-rays to produce detailed images. This radiation can cause cellular damage, which is why there is a small but real risk associated with their use. However, the diagnostic benefits often outweigh these risks, especially when scans are medically justified and optimized to use the lowest radiation dose possible.
