The first involves sheep. Researchers have found that hair sheep are a good source of blood for use in tests to diagnose infectious diseases in people.

VOA: special.2009.08.03

So tests often use human blood instead.

VOA: special.2009.08.03

A spokesman for the group says CT scans are frequently used in hospital emergency rooms because the results can be read quicker than with other tests, like ultrasound or MRIs, that do not use radiation.

VOA: standard.2010.01.30