Answer to Question #2672 Submitted to "Ask the Experts"

Q

I spent the afternoon with my dad at the hospital. He had a cardiac stress test and I was in the room with him for about three hours after he was done and then drove him home. I am just concerned about the amount of radiation that he was giving off and if it is harmful to me and my baby. I was sitting approximately 10 feet away from him in a chair at the foot of the bed.

A

Very good question and I'm happy to say that you don't need to worry because the amount of radiation exposure you and your baby may have received is very low. The cardiac stress test your dad had might have been done in nuclear medicine or in cardiology. If it was done in cardiology with x rays, you wouldn't have been exposed to radiation by being with him in the room. If the stress test was done in nuclear medicine, it is likely that they injected a radioactive material so they could take pictures of his heart. In a report by the National Council on Radiation Protection and Measurements (Report No. 124), there is information on dose rates from patients who have undergone various nuclear medicine tests.

There are a couple of types of stress tests in nuclear medicine and, according to the table in the report, the radiation dose rate at one meter would be 0.002 rem/hour at the most (rem is a unit of radiation dose). This means that if you were one meter from your dad for one hour, you would have received 0.002 rem. You stated you were about 10 feet (about three meters) away for three hours. Taking this into account, you would have received less than 0.001 rem and your baby even less than that. This is considered a negligible dose and does not need to be of concern. When the dose to the baby is less than 5 rem, scientific literature suggests there is no increased risk of birth defects or miscarriage.

Kelly Classic
Certified Medical Health Physicist