Ruth Williamson, MD - Medicare Radiation Oncology in Pasadena, CA

Ruth Williamson, MD is a medicare enrolled "Radiology - Radiation Oncology" physician in Pasadena, California. She went to University Of Southern California Keck School Of Medicine and graduated in 1989 and has 35 years of diverse experience with area of expertise as Radiation Oncology. She is a member of the group practice Cedars-sinai Medical Care Foundation and her current practice location is 625 S Fair Oaks Ave Ste 100, Pasadena, California. You can reach out to her office (for appointments etc.) via phone at (626) 397-5149.

Ruth Williamson is licensed to practice in California (license number G707B5C) and she also participates in the medicare program. She accepts medicare assignments (which means she accepts the Medicare-approved amount; you will not be billed for any more than the Medicare deductible and coinsurance) and her NPI Number is 1952486912.

Contact Information

Ruth Williamson, MD
625 S Fair Oaks Ave Ste 100,
Pasadena, CA 91105-2640
(626) 397-5149
(310) 397-2147

Map and Direction




Physician's Profile

Full NameRuth Williamson
GenderFemale
SpecialityRadiation Oncology
Experience35 Years
Location625 S Fair Oaks Ave Ste 100, Pasadena, California
Accepts Medicare AssignmentsYes. She accepts the Medicare-approved amount; you will not be billed for any more than the Medicare deductible and coinsurance.
  Medical Education and Training:
  • Ruth Williamson attended and graduated from University Of Southern California Keck School Of Medicine in 1989
  NPI Data:
  • NPI Number: 1952486912
  • Provider Enumeration Date: 10/26/2006
  • Last Update Date: 10/13/2022
  Medicare PECOS Information:
  • PECOS PAC ID: 7113057019
  • Enrollment ID: I20100618000425

Medical Identifiers

Medical identifiers for Ruth Williamson such as npi, medicare ID, medicare PIN, medicaid, etc.
IdentifierTypeStateIssuer
1952486912NPI-NPPES
GR0087110MedicaidCA

Medical Taxonomies and Licenses

TaxonomyTypeLicense (State)Status
2085R0001XRadiology - Radiation Oncology G707B5C (California)Primary

Medical Facilities Affiliation

Facility NameLocationFacility Type
Huntington Memorial HospitalPasadena, CAHospital

Group Practice Association

Group Practice NameGroup PECOS PAC IDNo. of Members
Cedars-sinai Medical Care Foundation09411066451208

Medicare Reassignments

Some practitioners may not bill the customers directly but medicare billing happens through clinics / group practice / hospitals where the provider works. Medicare reassignment of benefits is a mechanism by which practitioners allow third parties to bill and receive payment for medicare services performed by them. Ruth Williamson allows following entities to bill medicare on her behalf.
Entity NameCedars-sinai Medical Care Foundation
Entity TypePart B Supplier - Clinic/group Practice
Entity IdentifiersNPI Number: 1316984388
PECOS PAC ID: 0941106645
Enrollment ID: O20040202000464
Entity NameCity Of Hope Medical Foundation
Entity TypePart B Supplier - Clinic/group Practice
Entity IdentifiersNPI Number: 1871886366
PECOS PAC ID: 3779751656
Enrollment ID: O20110720000244

Medicare Part D Prescriber Enrollment

Any physician or other eligible professional who prescribes Part D drugs must either enroll in the Medicare program or opt out in order to prescribe drugs to their patients with Part D prescription drug benefit plans. Ruth Williamson is enrolled with medicare and thus, if eligible, can prescribe medicare part D drugs to patients with medicare part D benefits.

Mailing Address and Practice Location

Mailing AddressPractice Location Address
Ruth Williamson, MD
4140 W 190th St,
Torrance, CA 90504-5513

Ph: () -
Ruth Williamson, MD
625 S Fair Oaks Ave Ste 100,
Pasadena, CA 91105-2640

Ph: (626) 397-5149

Reviews and Comments


Radiology Doctors in Pasadena, CA

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Medicare Assignment: Assignment means that your doctor, provider, or supplier agrees (or is required by law) to accept the Medicare-approved amount as full payment for covered services. Most doctors, providers, and suppliers accept assignment, but you should always check to make sure. Participating providers have signed an agreement to accept assignment for all Medicare-covered services.

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