Radiation 101: Just How Much Does Each Imaging Scan Expose You To?

radiation exposure, xray radiation, mri radiation, CT radiation, mammogram radiation

It’s likely you already know that large doses of radiation can wreak havoc on your internal systems and even cause cancer long term. But how much radiation are you exposed to during common imaging tests and is it something you should be concerned about? With the prevalence of cancers in America, it’s only natural to be concerned about your exposure to radiation. Below we’ll take a look at different imaging procedures and radiation associated with each.

First of all, we need to take a look at the metrics used to measure radiation and how those apply. A millisievert is a measure of radiation exposure. The average American is exposed to 3 mSv of background radiation each year. Most commonplace imaging tests like dental x-rays or mammograms produce very little radiation exposure, while tests like CT/PET scans and nuclear imaging create more exposure to radiation. The amount of radiation also depends on the location of the scan.  

CT Scan

As mentioned, CT scan radiation will depend on the location of the scan.  A CT Scan of the lower abdomen, for instance, would likely cause 8-10 mSv of radiation exposure, while a CT scan of the head may only produce 3 mSv. Over 80 million CT Scans are performed in America each year, compared to only 3 million just a few decades ago. And this is for good reason, these tests have revolutionized the way physicians and specialists diagnose and treat illnesses, and early detection has proven to save many lives.

Nuclear Medicine Radiation

Nuclear imaging is a relatively new practice and, like CT scans, produces more residual radiation than say an x-ray. Nuclear imaging of a bone scan compared to that of a cardiac stress test will produce around 6 mSv and 40 mSv, respectively.


An MRI creates uses a large magnet to produce imaging using magnetic fields, so there is no exposure to radiation. Oftentimes, MRIs are the imaging method of choice when frequent imaging will be necessary for diagnosis or therapy. However, MRIs are generally more expensive than x-ray imaging or CT scanning.


Ultrasounds use sonography, or high-frequency sound waves to image the body, usually employing a probe called a transducer inside the body or directly onto the skin. Ultrasounds do not use radiation of any kind to create images of the body.


X-Rays have very low exposure to radiation, though it varies depending on what is x-rayed. Throughout the body, x-rays produce anywhere from 0.001 mSv, like an x-ray of an arm or leg to 1.5 mSv for an x-ray of the spine.  


A mammogram exposes a woman to around 0.4 mSv or about the amount of background radiation a person would expect to be exposed to over 7 weeks or so.

Since all of the abovementioned tests are used to diagnose harmful diseases or treat ailments, in most cases the risk of not getting one far outweighs the risk of residual radiation. If you’re concerned about radiation from a particular imaging test, speak with your healthcare provider. It’s important to keep the lines of communication open with you and your doctor to ensure you receive the proper test. You’re always in good hands with the specialists at BICRAD, who will always choose the imaging method that’s best for your health and wellbeing.