A scan of a baby's head is equivalent to between 200 and 600 chest X-rays.

对婴儿的头部进行一次扫描相当于进行了200至600次胸透。

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Objective To study the clinical value of chest Xray and spiral ct scan in diagnosis of mediastinal emphysema.

目的：探讨x线胸片和螺旋CT对纵隔气肿的诊断价值。

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But some doctors say the CT scan exposes patients unnecessarily to harmful radiation, as much radiation as a patient might receive from 400 chest x-rays.

VOA: standard.2010.04.07

Additionally, I have a chest x-ray every six months or so and a yearly CT scan.

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Then, in October, a CT scan showed that the tumor deposits in her left lung and chest and lymph nodes had grown substantially.

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