stevenp -- sorry, but I don't have any knowledge about that. One thing does come to mind though. Regardless of what the facts are, a bigger question might be your daughters' opinion/perspective of this (or for that matter your significant other as well). You might want to discuss this with her/them and see what they think. She might dismiss it without a concern, or she might be hyper-sensitive about it. Or maybe she'll compromise and agree to you wearing a radiation lap protector (like when you get an x-ray in the dentist office). In my case, my method of treatment was something my wife and I discussed extensively. She happened to be very supportive of what I wanted to do, but if she hadn't been, I probably would have factored that into (or at least strongly considered) whatever decision I ultimately made. Of course, some folks might justifiably hold a much differ view on what others think. I don't know what the "right" view is, but just thought I'd mention this for your consideration. Best wishes.

Brachytherapy seeds do emit some radiation but:
1,) the radiation only is effective for a short distance which is why your kidneys, penis, testicles, small intestine, stomach etc are not exposed to dangerous doses. I recall being told standing 2 feet from you get less radiation than they would from 3 hour flight in an airplane.
2.) the radiation does not last long. The radioactivity drops each day until the titanium seeds become inert. The half life of Iodine 125 is 60 days which means it broadcasts 1/2 the radiation in about two months. Two months laters its down another 50% and so on and so on.
3.) I was told not to have pregnant women and children sit on my lap for a period of about 6 weeks. This was based on the isotope and dosage that I received. You would need to ask your RO what temporary restriction you’d have in place.

If this is a concern, you may want to talk to a urologist that also does cryoablation for prostate cancer. Here’s the name of a doctor at Mayo that does both Brachy and cryo:
https://www.mayoclinic.org/tests-procedures/cryotherapy-for-prostate-cancer/doctors-departments/pdc-20384741

There are different situations whether it is HDL Brachytherapy ( Temporary Seeds ) or LDL Brachytherapy . ( Permanent Seeds ) . There are lots of on-line data sites , from reliable medical professionals , which address your question specifically by medical professionals .
If you are considering this procedure and depending on which one . Your doctor may issue you a " Radiation Letter " , if you are passing theouugh security at an Airport for example .