Answer to Question #4058 Submitted to "Ask the Experts"

I have the following questions: (1) Are there any health effects from medical ultrasound because I have had numerous of them in the past three years for some problems (cyst, kidneys, prostate, testicles)? (2) Are there any health effects from an MRI (magnetic resonance imaging)? I had one for my spine due to spondylolisthesis. (3) Am I in danger to get cancer from the x rays I’ve had? In my life (27 years) I had some x rays for medical reasons (surgical preparation) or for other reasons (joining the army or getting a job). I had a CT (computed tomography imaging) scan of the head 10 years ago, two or three panoramic x rays for my teeth and jaw, one pyelography when I was very young and one for the spine before the MRI to see what is happening. Now the question is am I in danger of cancer in any organ exposed to the x rays or for leukemia of the blood? Is radiation accumulative? Anyway should I worry?

Thank you for your questions. Let me take them individually.

Are there any health effects from [medical] ultrasound? There is no evidence that diagnostic levels of ultrasound cause long-term biological effects in humans. Ultrasound is a form of nonionizing radiation, unlike x rays which are ionizing radiation.

Are there any health effects from an MRI? This answer is the same as the first. There is no evidence that magnetic fields at diagnostic levels cause long-term biological effects in humans. As with ultrasound, MRI is a form of nonionizing radiation.

Am I in danger to get cancer from the x rays I've had? Any need for worry? In understanding the risks of diagnostic radiation exposures, the basis for the risks and putting them into perspective is not as simple as one would like. First of all, the estimates of risk are based on studies of people who received high radiation doses. These doses were usually well beyond typical diagnostic radiation exposure levels. From these high-dose survivors, a projected increased risk of developing cancer is 0.05% per 1,000 millirem (mrem) of exposure (millirem is a unit of effective whole body radiation dose). This means that if each of 10,000 individuals receives 1,000 mrem of radiation, there will be five additional cancers. In a population of 10,000 people, however, the normal cancer rate is already 25% even without radiation exposure - that means 2,500 of the 10,000 people will get cancer normally.

From the values listed in Question 708 of Ask the Experts, the effective dose for the x-ray studies mentioned in your question total 520 mrem. Therefore, an estimated increased cancer risk for your exams is 0.02%, for a total cancer risk of 25.02%. It is this potential 0.02% cancer risk increase against the risk of not getting your medical condition correctly diagnosed. This is a small risk.

Kelly Classic
Certified Medical Health Physicist