一辆装有爱克斯光安检仪的面包车长期停放在入口处，所有进入酒店的客人必须把携带的包袋放到车上通过检查。
A van with an X-ray security checkpoint was permanently parked outside the entrance. All visitors entering the hotel needed to pass their bags through the van first.
顺便提一下，大家可能想问：排队等待安检的普通旅客能看出这两种扫描仪的区别吗？
By the way, you might be wondering: Can the average traveler standing in a security line tell the difference?
于是他反向推算了一下扫描仪生成符合机场安检要求的图像所需的X射线剂量。
He calculated backward to figure out how big an X-ray dose would be needed to get the kind of images the machines produce.
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