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Radiation exposure guidelines for nuclear imaging

Posted on: 08.18.16

Radiation exposure guidelines for nuclear imaging

Advancements in medical imaging technology have revolutionized health care, allowing doctors to more accurately diagnose disease and improve patient outcomes with earlier treatment. These advancements include a variety of techniques including x-rays, CT scans, nuclear medicine scans, and MRI scans, which create detailed images and demonstrate the functionality of organs and tissue inside the body through the use of radiology or radiopharmaceuticals.

Should I be concerned?

The word radiation may stir-up heightened concern, especially if you are having multiple tests performed. How much radiation is considered safe and over what time period? Do some tests bring greater exposure than others? At what point should you be concerned? These are all valid questions, so let’s look at some guidelines and actual exposure levels that might help to ease your mind. The bottom line is that medical imaging is a safe, painless, and cost-effective way to diagnose and treat disease.

Radiation exposure

The international unit used to measure the amount of radiation received by a patient is the “millisievert” (mSv). We are exposed to small doses of background radiation every day from natural sources like cosmic rays from space, radioactivity in the earth, and from low levels of radon gas. The average radiation dose per year in the U.S. from background radiation is 3.1 mSv.

How much radiation is received from medical imaging?

The average effective dose from radiologic medical imaging depends on the test being performed. They can also vary substantially, depending on a person’s size as well as on differences in imaging practices. The following chart details several procedures and the approximate average dose:

Procedure Adult Approximate Effective Dose
Computed Tomography (CT)-Abdomen and Pelvis 10 mSv
Computed Tomography (CT)-Abdomen and Pelvis, repeated with and without contrast material 20 mSv
Computed Tomography (CT)-Colonography 6 mSv
Intravenous Pyelogram (IVP) 3 mSv
Radiography (X-ray)-Lower GI Tract 8 mSv
Radiography (X-ray)-Upper GI Tract 6 mSv
Radiography (X-ray)-Spine 1.5 mSv
Radiography (X-ray)-Extremity 0.001 mSv
Computed Tomography (CT)-Head 2 mSv
Computed Tomography (CT)-Head, repeated with and without contrast material 4 mSv
Computed Tomography (CT)-Spine 6 mSv
Computed Tomography (CT)-Chest 7 mSv
Computed Tomography (CT)-Lung Cancer Screening 1.5 mSv
Radiography-Chest 0.1 mSv
Intraoral X-ray 0.005 mSv
Coronary Computed Tomography Angiography (CTA) 12 mSv
Cardiac CT for Calcium Scoring 3 mSv
Cardiac SPECT (Myocardial Perfusion) 9.3 mSv
Bone Densitometry (DEXA) 0.001 mSv
Positron Emission Tomography – Computed Tomography (PET/CT) 25 mSv
Bone Densitometry (DEXA) 0.001 mSv
Mammography 0.4 mSv

Sources: and

Additionally, federal regulations allow professionals who work with ionizing radiation, such as Nuclear Medicine Technologists, Radiopharmacists, and Radiology Technologists, to receive up to 50 mSv of ionizing radiation per year of their professional lives, although most receive much less.

Is there a real risk?

Any medical procedure can have side effects, but when the procedure offers useful clinical information that will help your physician decide on your treatment, the benefits of the procedure far outweigh its very small potential risk. When you are better educated about the standard radiation guidelines and realistic radiation levels of a particular test, it may effectively ease your concerns and help you make a more informed decision.

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