Can only one chest xray damage some cells in d body.? m 20 year old female.

No: Not any more than a stroll in the summer sun. The problems caused by radiation exposure is a cumulative effect, and 1 single cxr is not going to pose any problems. The only exception to that is if you are pregnant and did not alert the x-ray tech to that possibility and the baby was exposed. Since cells are changing so rapidly in fetus, damage could potentially occur to fetus.