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Ralph B. Hanahan MD
Practice accepting new patients.

Ralph B. Hanahan MD

(707) 763-0600
Primary Specialties
  • Radiation Oncology
Medical Groups & Affiliations
  • St. Joseph Health Medical Group
  • Additional Languages Spoken

Primary Office

St. Joseph Health Medical Group
110 Lynch Creek Way
Suite A
Petaluma, CA 94954
(707) 763-0600
(707) 765-1757
Mon - Fri 8 a.m. - 5:30 p.m.
Web Page:

Secondary Office

(707) 528-1050
(707) 525-3874
Please call the office for current hours.

Physician Bio

Dr. Hanahan came to Redwood in 1974. After medical school at the University of South Carolina, he joined the Navy and did his residency in Radiology at Oakland Naval Hospital. He became Chief of Radiology, Radiation Oncology and Nuclear Medicine at St. Alban Naval Hospital in New York. When he resigned his commission, he did a second fellowship at UCSF's Mt. Zion Hospital and is board-certified in both Radiology and Radiation Oncology. Dr. Hanahan specializes in Prostate Cancer and began the seed implant program at Redwood in 1999.


  • College:
    The Citadel - Charleston, SC
  • Medical School:
    Medical University of South Carolina - Charleston, SC
  • Internship:
    US Naval Hospital - St. Albans, NY
  • Internship:
    USS Yellowstone - Mayport, FL
  • Residency:
    US Naval Hospital - Oakland, CA
  • Residency:
    US Naval Hospital - St. Albans, NY
  • Fellowship:
    Mt. Zion Hospital
  • Fellowship:
    Medical Center of San Francisco - San Francisco, CA


American Medical Association (AMA)
California Medical Association (CMA)
Sonoma County Medical Association (SCMA)
American College of Radiology (ACR) California Radiologic Society (CRS)
American Society for Therapeutic Radiology & Oncology (ASTRO)
Association Northern California Oncologist (ANCO)
Redwood Empire Radiologic Society
American Society ofClinical Oncologists (ASCO)