A friend of mine is a Colombian citizen and he was traveling to China with a group. Without any other evidence than being a Colombian citizen and holding a Colombian passport they X-rayed him.

Taking X-Rays is a medical procedure that increases the risk of cancer and X-Rays should not be taken without a medical reason. Since the live and health of westerners obviously are not valuable to chinese authorities they don't care. Be prepared to be submitted to routine X-Ray screening when arriving in China (and I am not talking about your carry on bag but about your body)