倫琴射線,何解可以透視身體內部生物結構?X光是否一定黑白照?

倫琴射線,何解可以透視身體內部生物結構?

Simply speaking, X-ray (i.e. Roentgen rays) is a penetrating ionizing radiation. It losses its energy through ionization of the material in its path. For x-rays within the diagnostic range, ionization is mainly attributed to photoelectric effect, which depends on the cube of the atomic number of the material. That is to say, materials with high atomic number absorb x-rays far better than materials with low atomic number.

In a human body, different organs are of different densities and hence different atomic numbers. Bone, for example, has higher density and atomic number than those of other tissue organs. Therefore, when a beam of x-ray passes through the human body, different absorptions in different organs will be resulted. Depending on the degrees of absorption of the incident x-ray, an image of the body organs can thus be produced.

Q: X光是否一定黑白照?
In fact, x-rays is NOT visible to the human eyes. There is no colour for x-ray. The black and white image that usually observed in an x-ray film is only because of the choice of the film (black and white film). Modern x-ray diagnostic technology using computer could "colour" the image with the intensities of x-ray received.

所謂的射線，只是些較可見光頻率更高的電磁波。

這些射線頻率高得足以穿過人體，但可以靠儀器調較出較低頻率的射線，使得射線只能穿肉而不能穿過骨頭，造成常見的x光照。

x光照的顏色取決於相底的化學結構。這些化學物質會因應電磁波的不炙頻繁而產生不同顏色。但為了方便作醫療診斷，通常會用對比度高的黑白相底。

x-ray9成醫院都是用黑白色的菲林............................