A heart CT calcium score test, also known as a coronary artery calcium (CAC) scan, involves a low level of radiation exposure typically around 1 to 1.5 millisieverts (mSv). This amount is considered quite low and is roughly equivalent to the natural background radiation a person receives from the environment over about four to six months. To put it in perspective, this dose is similar to or even less than that of some common screening tests like mammography.
This test uses specialized computed tomography imaging to detect and measure calcified plaque deposits in the coronary arteries. These calcium deposits indicate the presence of atherosclerosis, which can increase the risk of heart disease and heart attacks. The scan itself takes only about 10 minutes and does not require any contrast dye.
Radiation doses for CAC scans are kept deliberately low because they are intended for screening asymptomatic individuals who may be at risk but do not yet show symptoms. The typical effective dose ranges from approximately 0.9 mSv up to around 1.5 mSv depending on the specific scanner technology and protocol used by different medical facilities.
For comparison:
– Natural environmental radiation exposure averages about 3 mSv per year.
– A standard chest X-ray delivers about 0.1 mSv.
– A full chest CT scan can deliver between 5–7 mSv or more.
– Mammograms usually expose patients to roughly 0.4–0.8 mSv.
Thus, a heart CT calcium score test exposes you to less radiation than many other diagnostic CT scans while providing valuable information on your cardiovascular health risk.
Advances in imaging technology continue reducing this dose further without compromising image quality or diagnostic accuracy by optimizing scanning protocols or using newer detectors that require less radiation.
Because this test involves ionizing radiation—which carries some theoretical cancer risk—it’s generally recommended primarily for people with intermediate risk factors for coronary artery disease rather than younger individuals with very low likelihood of plaque buildup.
In summary, while there is some exposure during a heart CT calcium score test, it remains minimal—about one-third or less compared with annual natural background exposure—and offers important benefits by helping doctors identify early signs of coronary artery disease before symptoms develop. This balance between very low radiation dose and significant clinical insight makes it an increasingly popular tool in preventive cardiology today.