Question

Some electromagnetic wave can pass through our human body, depending on their wavelength and our body density. When they penetrate us like gamma ray, x ray and... will we get damage? Or we only get damage when our body absorb the ray and turn to heat?

Answer 1

yes, x-rays and gamma rays do damage us. In small doses it doesn't matter. But cumulatively, it matters greatly. That's why if you work as a radiologist you wear a monitor all the time that measures your exposure to x-rays, to make sure your cumulative exposure isn't too great.

Answer 2

The question is:
(i) will we get damage when the ray penetrate us 100%?
(ii) we will only get damage when we absorb the ray and turn it into another ray or energy?

Answer 3

energy from x-rays and gamma rays come in very small quanta, very small quantities called photons. If you absorbed one photon, one quantum of an x-ray or gamma ray, the chances of it having a serious impact is zero percent.

So you question (i) doesn't make sense.

The answer to (ii) remains what I said above. If you absorb enough of this energy then it is damaging. It is theoretically possible that a quanta of such energy can pass all the way through your body. But it is not probable that if you exposed to a sustained burst of x-rays or gamma rays that you would not absorb at least a large portion of them, and if you get enough of them, that's dangerous.