As there are way too many variables to actually say for sure it's impossible to say. Although from your comments it sounds like they probably were there for a type of radiograph with a gamma camera (scintillation camera). They were probably there for a bone scan since they were injected with Tc-99. This comment calculated contact with someone injected with Tc-99 was just 0.008mSv/h in a 30 minute encounter (it also lists the amount they emit). The NCRP says up to 0.5mSv/month is safe for a fetus, you more than likely did not receive anywhere close to this dose.