正值月經,可以照X 光嘛?

If you are taking plain X ray, there is no problem for the menstration period.

If you have no menstration, the doctor will ask you wether you get pregnant or not or he may ask you last menstral period. It is because on the first trimester, the fetus will be affected by taking xray.

For Chest X ray is included as plain x-ray.