Ruth Williamson, MD

Ruth Williamson is a Radiation Oncology Physician provider (Radiology) practicing in Pasadena, CA, registered in the NPPES registry with NPI 1952486912 since 2006. The credential MD stands for Doctor of Medicine.

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NPI	1952486912
Entity type	Individual (Type 1)
Name	Ruth Williamson
Credential	MD
Sex	Female
Practice address	625 S FAIR OAKS AVE STE 100, Pasadena, CA, 91105
Phone	6263975149
Fax	3103972147
Enumeration date	2006-10-26
Last updated in NPPES	2022-10-13

Taxonomy & licenses

Taxonomy code	Specialty	Primary	License	State
2085R0001X	Radiation Oncology Physician	Primary	G707B5C	CA

MD — Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

Other identifiers

Identifier	Type	State	Issuer
GR0087110	Medicaid	CA	—

Copy-ready billing details

Provider: Ruth Williamson, MD
NPI: 1952486912
Taxonomy: 2085R0001X (Radiation Oncology Physician)
Address: 625 S FAIR OAKS AVE STE 100, Pasadena, CA, 91105

Other providers at this practice address

NPI	Name	Type	Specialty	Location
1053494914	Ramona Kyaw	Individual	Radiation Oncology Physician	Pasadena, CA
1053947630	Erika Winkler	Individual	Registered Dietitian	Pasadena, CA

Verify this record

Cross-check NPI 1952486912 against the authoritative CMS record: view Ruth Williamson on the official NPPES registry .

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes — even if the provider moves or changes specialty. Read the full guide or validate an NPI number.

Frequently asked questions

What is the NPI number for Ruth Williamson?

The National Provider Identifier (NPI) for Ruth Williamson is 1952486912, a Type 1 (individual) record in the CMS NPPES registry.

Where does Ruth Williamson practice?

The practice location on file with NPPES is in Pasadena, CA. Providers can have multiple locations; NPPES lists the primary practice address.

Source: CMS NPPES (public data). Snapshot 2026-07-11. Provider record last updated 2022-10-13.