What is the average radiation dose from a ct scan

There's always questions about radiation exposure from medical imaging. Patients want to know if radiation from mammograms , bone density tests , computed tomography CT scans, and so forth will increase their risk of developing cancer. For most women, there's very little risk from routine x-ray imaging such as mammography or dental x-rays.

But many experts are concerned about an explosion in the use of higher radiation—dose tests, such as CT and nuclear imaging. Over 80 million CT scans are performed in the United States each year, compared with just three million in There are good reasons for this trend. CT scanning and nuclear imaging have revolutionized diagnosis and treatment, almost eliminating the need for once-common exploratory surgeries and many other invasive and potentially risky procedures.

The benefits of these tests, when they're appropriate, far outweigh any radiation-associated cancer risks, and the risk from a single CT scan or nuclear imaging test is quite small. But are we courting future public health problems?

The radiation you get from x-ray, CT, and nuclear imaging is ionizing radiation — high-energy wavelengths or particles that penetrate tissue to reveal the body's internal organs and structures. Ionizing radiation can damage DNA, and although your cells repair most of the damage, they sometimes do the job imperfectly, leaving small areas of "misrepair.

We're exposed to small doses of ionizing radiation from natural sources all the time — in particular, cosmic radiation, mainly from the sun, and radon, a radioactive gas that comes from the natural breakdown of uranium in soil, rock, water, and building materials. How much of this so-called background radiation you are exposed to depends on many factors, including altitude and home ventilation. But the average is 3 millisieverts mSv per year.

A millisievert is a measure of radiation exposure; see "Measuring radiation. Exposure to ionizing radiation from natural or background sources hasn't changed since about , but Americans' total per capita radiation exposure has nearly doubled, and experts believe the main reason is increased use of medical imaging. If you mention the measurement of radiation, many people will recall the classic Geiger counter with its crescendo of clicks. But Geiger counters detect only the intensity of radioactive emissions.

Measuring their impact on human tissues and health is more difficult. Some imaging tests and treatments have special pediatric considerations. The teddy bear denotes child-specific content. Please contact your physician with specific medical questions or for a referral to a radiologist or other physician. To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database.

This website does not provide cost information. The costs for specific medical imaging tests, treatments and procedures may vary by geographic region. Web page review process: This Web page is reviewed regularly by a physician with expertise in the medical area presented and is further reviewed by committees from the Radiological Society of North America RSNA and the American College of Radiology ACR , comprising physicians with expertise in several radiologic areas.

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Measuring radiation dosage Naturally occurring "background" radiation Effective radiation dose in adults Benefit versus risk. Measuring radiation dosage When radiation passes through the body, some of it is absorbed. Naturally occurring "background" radiation We are exposed to natural sources of radiation all the time. Effective radiation dose in adults Here are some approximate comparisons of background radiation and effective radiation dose in adults for several radiology procedures described on this website.

X-ray Less than 0. Benefit versus risk The risk associated with medical imaging procedures refers to possible long-term or short-term side effects. Send us your feedback Did you find the information you were looking for? Yes No. Area Code:. Phone no:. Patient undergoing computed tomography CT scan. View full size with caption. Pediatric Content Some imaging tests and treatments have special pediatric considerations.

RadInfo 4 Kids. English and Spanish examples of imaging records for adults can be found online at www. Children are more sensitive to radiation than adults. Because of this, health care providers are careful to reduce radiation exposure to pediatric patients for imaging tests that use radiation.

Still, parents can and should ask questions before any imaging tests are done. An English version for children can be found online at www. Radiation experts believe that if imaging tests do increase the risk of cancer, the increase in risk is likely to be very small.

Most studies on radiation and cancer risk have looked at people exposed to very high doses of radiation, such as uranium miners and atomic bomb survivors.

The risk from low-level radiation exposure is not easy to calculate from these studies. We do know that children are more sensitive to radiation and should be protected from it as much as possible. Because radiation exposure from all sources can add up over a lifetime, and radiation can, indeed, increase cancer risk, imaging tests that use radiation should only be done for a good reason.