The ABZs of Pediatric CT

The ABZs of pediatric CT? Is this a typo? Why a hybrid between the ABCs and A through Zs? The first  representation is a fundamental guide and the latter a comprehensive missive; which is it?

Source: Journal of the American College of Radiology : JACR - November 1, 2018 Category: Radiology Authors: Donald P. Frush Tags: Radiation sensibilities Source Type: research