Answer to Question #4883 Submitted to "Ask the Experts"

Q

Due to an accident, I had to undergo partial hip replacement surgery five months ago and have had numerous x rays of my hip, chest, and knees. Just previous to this surgery, I took my yearly mammogram and chest x ray. My doctor would like me to take a routine stress test. I had asked the cardiologist about the radiation exposure; he said it is minimal. I would like to know the amount of radiation content for the nuclear dye injection that's given. Am I exposing myself to too much radiation that could be harmful and cumulative in the future? Should I wait a few months to lessen the exposure? I am a healthy 75-year-old female.

A

If your doctor is interested in a nuclear medicine stress test, I would not delay it at all due to concerns about radiation doses. The routine mammogram and chest x ray involve relatively low radiation doses. The other exams done in relation to your accident probably involved higher doses, but levels that we would still characterize as "low" in the overall scheme of things.

Not knowing exactly which test will be administered, and with how much activity, I cannot give any kind of precise estimate of the dose. One source shows that for a commonly used test (^99mTc Sestamibi) the effective dose might be about 5.8 mSv (580 mrem), which is comparable to our typical radiation exposures from background radiation over two years or so. It sounds like you are doing a great job with your personal medical care and are staying informed about the procedures involved; this is highly desirable and you are to be commended.

The radiation doses from diagnostic medical procedures give you direct benefits and involve very small, if any, risks from side effects of the radiation. If you and your physician agree that the test will yield some useful information, then concerns about the small radiation doses involved should not preclude any needed test.

Michael G. Stabin, PhD, CHP