As discussed in an earlier post, the effect of the gamma radiation to other people is easily eliminated by distance. One point to make is that walls in your house do not necessarily provide the same protection as distance. Since most walls are constructed of a wood skeleton and covered with sheet rock (plasterboard), they are not dense enough to act as shielding. Therefore, if for instance the bed in your isolation room shares a wall with a bed on the other side of the wall that a family member is sleeping in, you should consider moving it across the room or not sleeping in it. Sleeping “head to head” with only a wall separating you, is the same effect as being only a very few feet away for the entire night.
The real concern with radiation exposure to others in your family has more to do with them coming into contact with actual contamination. This is of particular concern because this can lead to internal uptake with the radioactive iodine then accumulating in their thyroids. If a person with a health thyroid intakes the I131, it will damage their thyroid tissue and potentially lead to future thyroid problems. Since Children have smaller thyroids then adults, the impact of contamination is greater. It is especially important for children and pregnant women not to come into contact with contaminated areas.
Since the excess radioactive iodine is being eliminated from your body through urine, sweat, saliva, tears, even breathing and blowing your nose, it is almost impossible not to cause contamination that others may come into contact with. This is the main reason why most countries isolate treated patients in the hospital for several days to minimize the risks of exposing others to the dangers of radioiodine contamination.
Hospitals which have isolation rooms go to great lengths to cover all surfaces with plastic to minimize contamination. If you have any doubts about this, take a look at the following video which shows hospital staff preparing an isolation room for patient use: ROOM PREP FOR I131 THERAPY
Even with all that room preparation, contamination still occurs. Radioiodine is very adept at getting into crevices and hard to reach places, leading hospitals have found that the most effective way to clean up radioiodine contamination is with Bind-It™.