Potential adverse effects, namely cancer, are associated with radiation exposure. It has been estimated that approximately 1 in 1000 individuals will develop cancer from an exposure of 10 mSv. This risk is relatively small when compared to the 420 out of 1000 individuals expected to develop cancer from all other causes combined. Although small, radiation exposure is important to consider when selecting an appropriate imaging modality. There are a wide range of radiation exposures associated with different diagnostic procedures.
| Relative Radiation Level | Effective Dose Estimate Range | Example Examinations |
| None | 0 | Ultrasound, MRI |
| Minimal | <0.1 mSv | Chest radiographs, hand radiographs |
| Low | 0.1-1 mSv | Pelvis radiographs, mammography |
| Medium | 1-10 mSv | Abdomen CT, barium enema, nuclear medicine bone scan |
| High | 10-100 mSv | Abdomen CT with and without contrast, whole body PET |
In addition to radiation exposure from imaging procedures, individuals are also exposed to background radiation from natural sources, including radon, cosmic rays, soil, building materials, and food. The average annual amount of natural background radiation for someone living in the US is approximately 3 mSv.
Please keep in mind that radiation-induced cancer mortality risk in children is 3 to 5 times higher than for adults. The developing fetus is also sensitive to radiation exposure in utero, which may result in mental retardation, organ malformations, and childhood cancer.
Although the overall risk of developing cancer from diagnostic imaging is small, it is not zero. It is important to minimize patient radiation exposure and avoid ordering unnecessary examinations