The scanning machines, called "backscatter scanners," deliver a dose of ionizing radiation equivalent to 1 percent or less of the radiation in a dental X-ray.
扫描机，所谓的“反射散射扫描仪”，发射出的电离辐射剂量相当于牙科辐射X射线的1%或更少。
2
The X-ray pulses have a shutter speed of less than 100 femtoseconds (100 femtoseconds = 1/10 of a trillionth of a second).
这种X光脉冲快门速度不到100飞秒（100飞秒= 万亿分之一秒的1/10）。
3
TRAPPIST-1 emits about the same amount of X-ray and ultraviolet radiation as the Sun does, which could chew away at any protective atmospheres the planets might have.