ACR Appropriateness Criteria® Patient Age Definitions

Definition of terms used to describe patient age information in the ACR Appropriateness Criteria® topics.

Neonate – Birth to one month old1

Infant – Birth to one year old2

Child – Birth to 18 years old, unless otherwise specified3

Adolescent – A transitional stage of physical development occurring between puberty and adulthood4

Adult – Greater than 18 years old, unless otherwise specified


1Merriam-Webster Dictionary. Accessed March 21, 2011.

2World Population Prospects: The 2008 Revison Population Database. Accessed March 21, 2011.

3Convention on the Rights of the Child. UNICEF publications. Accessed March 21, 2011.

4Christie D, Viner R. Adolescent development. BMJ. 2005;330(7486):301-304.