In this way, an X-ray is a shadow, it's an inverse image of the density

如此 X射线片是一种影子
through which the X-ray passed.

它跟其被穿过物体的密度负相关
The diagram over here shows you a more sophisticated setup

这里的图片展示了一种更加复杂的设备
and the kind of setup that's used for X-ray imaging in patients.

这种是用于给病人摄片的X射线机
You have an X-ray source and so X-rays are emitted from this source.

有X射线源 X射线从中发射而出
If you didn't confine those X-rays in some ways

如果不用某种方法限制X射线
they would be emitted in all directions.

它将向各个方向发射
You confine it so that X-rays are only emitted from one side.

加以限制光线就会从一个方向射出
You let that pass through a filter

让光源的光线通过滤波器
because these sources of X-ray generation are not perfect,

因为X射线源产生的光线并不完美
they generate waves of different wavelengths.

它们产生不同波长的波
So, through a filter that only lets X-rays pass through,

所以要通过一个只允许X射线通过的滤波器