A CT scan generally exposes a person to **significantly more radiation** than a mammogram. To understand why, it helps to look at what each procedure involves and how much radiation they typically use.
A **mammogram** is a specialized X-ray of the breast used primarily for breast cancer screening. It uses a relatively low dose of radiation—roughly equivalent to what you might receive from natural background radiation over about two months or the amount of radiation from a cross-country airplane flight. Modern mammography equipment is designed to minimize radiation exposure while still producing high-quality images. Even when 3D mammography (tomosynthesis) is added, which involves taking multiple images from different angles, the total radiation dose remains low and well within safety limits regulated by health authorities.
In contrast, a **CT scan (computed tomography)** is a more complex imaging technique that takes multiple X-ray images from different angles around the body and uses computer processing to create detailed cross-sectional images. Because it captures many slices and more detailed views, a CT scan requires a much higher dose of radiation compared to a single mammogram. For example, a typical chest CT scan can expose a patient to radiation equivalent to several years’ worth of natural background radiation, far exceeding the dose from a mammogram.
To put it simply:
– **Mammogram radiation dose:** About the same as 1-2 months of natural background radiation.
– **CT scan radiation dose:** Can be equivalent to several years of natural background radiation, depending on the type and area scanned.
This difference exists because CT scans provide much more detailed images and cover larger areas of the body, requiring more X-ray exposures. Mammograms focus on a small area (the breast) and use lower doses optimized for screening purposes.
Despite the higher radiation dose from CT scans, both mammograms and CT scans are considered safe when used appropriately. The benefits of early detection and accurate diagnosis usually outweigh the small risks associated with radiation exposure. For mammograms, the radiation dose is low enough that annual screening is recommended for women at average risk without significant concern about radiation harm. CT scans are used more selectively, often when detailed imaging is necessary for diagnosis or treatment planning.
In summary, a CT scan involves **much more radiation exposure** than a mammogram, but both are carefully controlled to keep radiation doses as low as possible while providing valuable medical information.
