Testing for Concussions When a patient is suspected of having a concussion, or brain injury, doctors often turn to
computed tomography, or CT, scans to find out for sure. In a CT scan, a series of X-rays
is taken. Each one shows an individual "slice" of the brain, and they can be combined to
form a complete three-dimensional picture. Because of the amount of radiation patients
are exposed to, however, doctors question the use of the scans, especially for children.
Now researchers have proposed an alternative way of diagnosing head injuries: a simple
blood test. The test detects proteins that burst out of brain cells into the bloodstream
immediately after an injury. It allows doctors to determine whether a patient has suffered
head trauma and needs further treatment.
What is the main idea of the passage?

A: A new blood test makes it easier-and safer-to detect concussions.

B: Doctors commonly use CT scans to test for brain injuries.

C: A new blood test can identify proteins that are present in the blood following a
brain injury