Answer to Question #6940 Submitted to "Ask the Experts"

Category: Nuclear Medicine Patient Issues — Diagnostic Nuclear Medicine

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


After experiencing some symptoms typical of a heart condition, I registered at an emergency room in our local hospital with my complaints. There I was treated and the test taken showed positive results . . . that is I was not having, nor have I had, a heart attack in recent days. Heart conditions are very prevalent in our family and upon discharge I was given an appointment for a stress test. The stress test showed very little to indicate heart damage (I'm in my early 40s) yet given the family history, the cardiac specialist thought it necessary to investigate further with a nuclear medicine stress test. This test was done in two parts: one at rest for which I was given a radioactive injection, and one the following day with exercise for which I was given another radioactive injection. Having just finished an article on the levels of radioactivity of a heart stress test, I'm now concerned having found that I received well over five times the radiation level I would receive normally from background radiation per year.

What can I do today to minimize long-term effects?


First of all, I am pleased that your diagnosis was negative for a potentially serious medical problem. From the description of your exam, it sounds as if you had a two-phase stress test. An example of the exposure values can be found in our fact sheet "Radiation Exposure From Medical Diagnostic Imaging Procedures" for the stress and resting heart exam using 99mTc sestamibi (Cardiolite®) in the table for Nuclear Medicine Examinations. I would estimate your radiation dose at approximately 12 millisievert (mSv).

All medical procedures involve a risk-versus-benefit decision made by the doctor. The risk was small for the radiation exposure received compared to the benefit you received. You had a noninvasive study that can actually record heart function and be reviewed by a doctor that could reveal heart problems in a relatively easy manner. It involved much less risk compared to cardiac catheterization, which itself is less risky than surgery. As noted in the Health Physics Society Position Statement on "Radiation Risks in Perspective," there is no demonstrated health effect for radiation exposures below 50-100 mSv.

I do not think you received too much radiation for this type of exam. And I do not think it is practical to compare a medical procedure's radiation exposure to natural background radiation, although I know it is done at some hospitals.

Marcia Hartman, MS

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 6 November 2007. 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.