A chest radiograph (x-ray) doses you with about 0.1 mSv of radiation which is EXTREMELY low. Your body is naturally exposed to this in 10 days of just living and going about your life. To give perspective, 70 chest x-rays is equivalent to one CAT scan which is still very low radiation exposure. So go ahead as have as many chest x-rays as you want. I'm not a doctor but I play one on the internet.