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19 March 2010

Answer to Question #8077 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:

I had a nuclear bone scan. The administered activity was 25 mCi. What was my exposure from this scan? My understanding is that the bladder gets much more radiation exposure than the rest of the body. If I started drinking right away and drank more and more and used the restroom several times during the two-hour wait, did that help? Is the following accurate?

Bladder wall, 2-hour void, 2.6 rad/mCi
Bladder wall, 4.8-hour void, 6.20 rad/mCi

The total effective dose for your study is 527 millirem. Every person is different and since you drank a lot of water, you probably received a lower dose, although I don't know exactly how much lower.

The information that you list from the package insert is correct for a person who receives 20 millicuries and holds his/her bladder and does not go to the bathroom for two hours. For someone who receives 25 millicuries and holds his/her bladder for two hours, the bladder dose would be 3.25 rad. Since you started drinking water and going to the bathroom as soon as possible, your dose was definitely lower than that.

So you did as well as a person could to reduce the dose from radiation.

All medical procedures involve a risk-versus-benefit decision made by the doctor. The risk is small for the radiation exposure compared to the benefit you received. As noted in the Health Physics Society Position Statement "Radiation Risk in Perspective," there is no demonstrated health effect for radiation exposures below 5-10 rem (50-100 millisievert).

Marcia Hartman, MS

Answer posted on 2 April 2009. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of 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 specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.