Child

The boy was playing outside his home in Calabasas in the Santa Monica mountains, west of Los Angeles, when the lion pounced on him.

The child was dragged across the front lawn, but his mother ran out and struck the mountain lion with her bare hands until it let go of her son.

The animal was later found and shot dead by wildlife authorities.

The boy suffered injuries to his head and torso, but is now in a stable condition at a hospital in Los Angeles, the Associated Press news agency reports.

CT scans are used by doctors to get to the core of a problem by creating a 3D image of the most inaccessible nooks of the body.

But the beams of ionising radiation can cause cellular damage.

A fresh analysis of 2013 research is being presented by researchers from the University of Melbourne at the World Congress of Public Health in Melbourne.

They said the radiation risk was much greater than previously acknowledged.

The results indicated that most of the excess cancers occurring more than two years after a CT scan were caused by radiation from the scan.