hi all i run in to some contradictions while studing electromagnetics. you know skin depth decreases when frequency increases.It ans that waves of higher frequencies have lower skin depth. ok and every one of us knows that X-ray have higher frequencies than other waves for example radio frequencies. so why X-ray used in hospitals to take photoes from insde of body? i meant according to skin depth formula X-ray have to have less skin depth in comparison with radio frequencies why radio frequencies can not be used?