The NPI (National Provider Identifier) code for another physician involved in the care of the patient. NPI, a unique identification number for US health care providers, was scheduled for 2007-2008 implementation by the Centers for Medicare & Medicaid Services (CMS) as part of the Health Insurance Portability and Accountability Act of 1996 (HIPAA). For billing purposes, large practices and large group providers were required to use NPI codes by May 2007; small health plans were required to use NPI codes by May 2008.

Used to monitor patient radiotherapy care.