Ruth Williamson, MD
NPI 1952486912 · Radiation Oncology Physician · Pasadena, CA
Enrolled with Medicare as Practitioner - Radiation Oncology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Ruth Williamson, MD is a Radiation Oncology Physician provider in Pasadena, CA (NPI 1952486912).
Provider details
- NPI number
- 1952486912
- Entity type
- Individual
- Primary specialty
- Radiation Oncology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Female
- Sole proprietor
- No
- License
- G707B5C (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
19 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
2 documented practice locations
- Medicare service volume (vs. specialty peers)28% of score
1,515 Medicare services, 2024 (ranked within specialty)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Ct Guidance for Insertion of Radiation Therapy Fields77014 | 356 | $48 |
| Design and Construction of Complex Radiation Treatment Device77334 | 304 | $64 |
| Radiation Treatment Management, 5 Treatment Sessions77427 | 234 | $203 |
| Calculation of Radiation Therapy Dose77300 | 219 | $35 |
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 107 | $102 |
| Obtaining Data Needed to Develop the Optimal Radiation Treatment, 3 Or More Treatment Areas Or Any Number of Treatment Areas Where Special Treatment Is Involved77290 | 77 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 1 distinct drug on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Clobetasol Propionate | 28 | 23 |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they do notinclude cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means no Part D record, never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Practice location
Mailing address
Additional practice locations (1)
- 100 W California BlvdPasadena, CA 91105-3010Phone: (626) 397-5149
Registry dates
- Enumerated
- 2006-10-26
- Last updated
- 2022-10-13
- Certified
- 2022-10-13
Frequently asked questions
- What is Ruth Williamson's NPI number?
- Ruth Williamson's National Provider Identifier (NPI) is 1952486912, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Ruth Williamson's specialty?
- Ruth Williamson is listed in the NPPES registry with a primary specialty of Radiation Oncology Physician (Allopathic & Osteopathic Physicians).
- Where is Ruth Williamson located?
- Ruth Williamson's practice location on file with NPPES is 625 S Fair Oaks Ave Ste 100, Pasadena, CA 91105-2640.
- What is Ruth Williamson's phone number?
- The practice phone number listed in the NPPES registry for Ruth Williamson is (626) 397-5149.
- Does Ruth Williamson accept Medicare?
- Ruth Williamson is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Ruth Williamson's NPI active?
- Yes — Ruth Williamson's NPI (1952486912) is active in the NPPES registry as of the last update on 2022-10-13.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.