A radiotracer is a radioactive compound that is safe to inject into patients and shows up clearly on a scan.

这种放射示踪剂是一种具有放射活性的复合物，具有注射安全且扫描显示清晰的优点。

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Workers are attempting to remove the radioactive water from the tsunami-ravaged nuclear compound and restart the regular cooling systems for the dangerously hot fuel.

工作人员正试图把有高辐射积水从被海啸破坏的核化合物中分离出来，并且重启常规制冷系统以冷却这些危险的高热燃料。

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At the same time, their brains were scanned with positron emission technology (PET), using a radioactive compound that allowed the researchers to visualize where caffeine was going once it arrived in the brain.

FORBES: A Snapshot of Caffeine's Fascinating Effects On The Brain