No.
Particles implanted in the prostate gland cover only 3 to 8 mm of the prescribed dose in and around the prostate gland, and the treatment takes advantage of the fact that tumor cells are genetically unstable and very sensitive to radiation and will die quickly after being damaged, while normal tissue cells are relatively resistant and generally do not suffer excessive damage. For example, iodine-125 particles are a miniature radiation source with an effective radius of only 10 mm and a half-life of about 60 days in the body.
So, implanted particles do not affect the loved ones around the patient because of the limited distance of impact.
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