Answer to Question #7597 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues — Diagnostic X Ray and CT

The following question was answered by an expert in the appropriate field:

Q

Three months ago I had a full-body (from shoulders to pelvis) CT (computerized tomography) scan which revealed a hypodense lesion of my pancreas tail. Since I have never been a smoker or drinker I am not at high risk for cancer but I asked my doctor if he felt we should follow up and a month later he did order an MRI (magnetic resonance imaging) with contrast of just the pancreas, which showed it was just a benign cyst.

A month later (last month) I began having stomach issues/pain so they ordered another CT of the pelvis as they thought perhaps I had kidney stones. This was negative but the stomach pain increased so severely for the past few weeks that yesterday they repeated a CT of the full abdomen and pelvis with contrast dye and a barium swallow. This was negative as well.

I am a highly educated (PhD) extremely health-conscious individual who avoids carcinogens and x rays. I have never had a cavity in my life so I even refuse dental x rays. Unfortunately I am very concerned about the level of radiation I have been exposed to in three months with three CT scans (I assume the MRI involves no radiation). My whole family tested as very high in uranium three years ago because our well at the time was high in uranium. A naturopathic doctor who specializes in toxicity issues has treated us with chelating agents to eradicate the uranium successfully.

I have been loading up on antioxidants since my third CT scan yesterday and am taking mild herbal laxatives to speed expelling the barium. My stomach has been very queasy since yesterday's scan. I have read these scans are a tremendous exposure to radiation—equal to several years' worth of normal exposure. Could I have radiation sickness? Could the exposure damage my arteries in any way? My mother's arteries were damaged from breast-cancer radiation and my brother-in-law died of arterial disease at a very young age due to radiation treatments also.

I have been through enough stress already and would be so very grateful for any accurate information as to the risks I should be aware of from these recent tests. My yearly mammogram is due and I am thinking of skipping a year in light of all the recent exposure, although I understand the radiation is small from mammograms.
 

A

Thank you for your questions. It was good to read that your pancreatic cyst wasn't cancer.

The radiation dose from a CT scan is large (10–20 mSv; mSv is a unit of effective radiation dose)—but large compared to what? Compared to a chest x ray, which is about 0.5 mSv. Compared to a year's worth of natural background radiation, which is about 3.1 mSv. But not compared to radiation doses commonly received by a patient undergoing radiation therapy, who will receive hundreds of mSv.

Compared to the normal incidence of cancer for people in the United States (according to the American Cancer Society), which is 42 percent, your risk of cancer was not increased appreciably either.

Radiation sickness would not occur unless you received whole-body radiation doses in excess of a few thousand mSv. In fact, it takes a minimum of about 200 mSv before we see any clinical symptoms of an exposure (and at doses that low, those effects are decreases in blood cell counts, which rapidly come back on their own).

There are a couple of other places with information that might be of interest. The first is www.radiationanswers.org. On that site what would be of most interest to you would be the data under the "Radiation & Me" section. There also is another place on the Health Physics Society site that has common medical doses.

Kelly Classic
Certified Medical Health Physicist
 

Answer posted on 3 June 2008. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.