Radiation Oncologists in California
Data updated monthly · Last refresh October 2026
734 Radiation Oncology providers practice in California, including 310 (42%) offering telehealth. The largest concentration is in Los Angeles. Profiles include federal Open Payments records of money received from drug and device companies in 2025. Listings are drawn from federal public records and are not endorsements.
734providers
310telehealth
Los Angelestop city
Radiation Oncology by city in California
Choose a city to see providers there.
Radiation Oncology providers in California
Listed by city, largest first. Payment figures come from the federal Open Payments program, which requires drug and device companies to report what they pay physicians for consulting, speaking, meals, travel and royalties. A disclosed payment is a financial relationship, not evidence of wrongdoing, and many totals reflect a single meal. Figures cover calendar year 2025.
Dr. Sammy Ashouri, M.D.Stanford, CA · No drug or device payments recorded (2025) ·
(650) 725-1812 Dr. Sandra Zaky, MDStanford, CA · $47 in drug and device payments (2025) · Telehealth ·
(650) 723-4000 Dr. Santino Butler, MDStanford, CA · No drug or device payments recorded (2025) · Telehealth ·
(650) 723-4000 Dr. Sarah Donaldson, M.D.Stanford, CA · No drug or device payments recorded (2025) ·
(650) 723-4000 Dr. Scott Bratman, MD, PHDStanford, CA · No drug or device payments recorded (2025) ·
(650) 723-6171 Dr. Scott Soltys, MDStanford, CA · $1,412 in drug and device payments (2025) · Telehealth ·
(650) 724-1569 Dr. Steven Hancock, M.D.Stanford, CA · No drug or device payments recorded (2025) ·
(650) 723-6440 Dr. Wendy Hara, M.D.Stanford, CA · No drug or device payments recorded (2025) ·
(650) 725-4779 Dr. Yushen Qian, M.D.Stanford, CA · No drug or device payments recorded (2025) · Telehealth ·
(650) 723-4000 Dr. Dan Vongtama, M.D.Stockton, CA · $135 in drug and device payments (2025) ·
(209) 472-1848 Dr. Gauravjit Singh, MDStockton, CA · $272 in drug and device payments (2025) ·
(209) 946-6800 Dr. Muhtada Kamal AldinStockton, CA · No drug or device payments recorded (2025) ·
(209) 471-1848 Dr. Vitune Vongtama, MDStockton, CA · No drug or device payments recorded (2025) ·
(209) 472-1848 Dr. Rex Hoffman, MDStudio City, CA · No drug or device payments recorded (2025) ·
(818) 506-4074 Dr. Sharon Dutton, M.D.Sunnyvale, CA · $135 in drug and device payments (2025) · Telehealth ·
(650) 934-7600 Dr. Zachary Zumsteg, M.D.Sylmar, CA · No drug or device payments recorded (2025) · Telehealth ·
(818) 364-1555 Dr. Marc Botnick, MDTarzana, CA · $304 in drug and device payments (2025) · Telehealth ·
(424) 314-7695 Dr. Brian Ronson, MDTemecula, CA · $1,680 in drug and device payments (2025) · Telehealth ·
(951) 252-9300 Dr. Tara Washington, MDTemecula, CA · $167 in drug and device payments (2025) ·
(951) 252-9300 Dr. James Longo, MDTempleton, CA · No drug or device payments recorded (2025) ·
(805) 434-1859 Dr. Jonathan Abelson, M.D.Thousand Oaks, CA · $33 in drug and device payments (2025) ·
(805) 496-4111 Dr. Paul Miller, MDThousand Oaks, CA · $33 in drug and device payments (2025) ·
(805) 496-4111 Dr. Allan Rappaport, M.D., J.D. Dr. Alessandra Amadeo, MDTorrance, CA · No drug or device payments recorded (2025) ·
(310) 792-6539 Dr. Andrew Schumacher, M.D.Torrance, CA · $40 in drug and device payments (2025) · Telehealth ·
(310) 517-4750 Dr. Arthur Zimmerman, M.D.Torrance, CA · No drug or device payments recorded (2025) ·
(310) 222-2804 Dr. Garth GreenTorrance, CA · No drug or device payments recorded (2025) · Telehealth ·
(310) 750-1715 Dr. Rebecca Philipson, M.D.Torrance, CA · $40 in drug and device payments (2025) · Telehealth ·
(310) 517-4750 Dr. Samuel Zhang, MDTorrance, CA · $20 in drug and device payments (2025) · Telehealth ·
(310) 517-4750 Dr. Thomas Simko, MDTorrance, CA · No drug or device payments recorded (2025) ·
(909) 263-0321 Dr. David Eastham, MD, MPHTravis Afb, CA · $50 in drug and device payments (2025) ·
(707) 423-7691 Dr. Winnifred Wong, DOTravis Afb, CA · $631 in drug and device payments (2025) ·
(707) 423-7691 Dr. Jorge Weibel, M.D.Trinidad, CA · No drug or device payments recorded (2025) ·
(707) 677-3339 Dr. Daphne Palmer, MDTruckee, CA · No drug or device payments recorded (2025) ·
(530) 582-6450 Dr. Christopher Neville, M.D.Turlock, CA · $340 in drug and device payments (2025) ·
(209) 664-5030 Dr. Haocheng Cai, DO, PHD Dr. Paul Kim, M.D.Tustin, CA · $206 in drug and device payments (2025) · Telehealth ·
(949) 381-5800 Dr. Tapan Roy, M.D.Tustin, CA · No drug or device payments recorded (2025) ·
(714) 573-9500 Dr. Jay Joseph, M.D.Ukiah, CA · $227 in drug and device payments (2025) · Telehealth ·
(707) 463-3636 Dr. Mark Bisignani, MDUkiah, CA · No drug or device payments recorded (2025) ·
(707) 463-3636 Dr. Michael Weil, MDUkiah, CA · No drug or device payments recorded (2025) ·
(707) 463-3636 Dr. Cecil Benitez, M.D., PH.D.Upland, CA · No drug or device payments recorded (2025) ·
(909) 949-2242 Dr. Sean Szeja, M.D.Upland, CA · $229 in drug and device payments (2025) · Telehealth ·
(909) 949-2242 Dr. May Tao, MDValencia, CA · $62 in drug and device payments (2025) · Telehealth ·
(661) 839-1810 Dr. Nancy EllerbroekValencia, CA · No drug or device payments recorded (2025) ·
(661) 259-2990 Dr. Michael Zhang, M.D., PH.D.Vallejo, CA · $1,307 in drug and device payments (2025) · Telehealth ·
(707) 551-3400 Dr. Victor Schweitzer, MDValley Village, CA · No drug or device payments recorded (2025) ·
(818) 636-7506 Dr. Charu Singh, M.D.Ventura, CA · $232 in drug and device payments (2025) ·
(805) 648-5191 Dr. Jeffrey Rodnick, MDVentura, CA · $125 in drug and device payments (2025) ·
(805) 648-5191 Common questions
How many Radiation Oncology providers are in California?There are 734 Radiation Oncology providers with active NPI records practicing in California, according to federal NPPES data refreshed monthly.
Do Radiation Oncology providers in California offer telehealth?Yes. 310 of the 734 Radiation Oncology providers in California (about 42%) report offering telehealth services in CMS data.
Which cities in California have the most Radiation Oncology providers?Los Angeles (97), San Francisco (46), Stanford (43) have the highest concentration of Radiation Oncology providers in California.
How many Radiation Oncology providers in California received drug or device company payments?359 of 734 Radiation Oncology providers in California (49%) received at least one payment from a drug or device company in 2025, according to the federal Open Payments program.
Where does this data come from?Provider counts and profiles come from the federal NPPES registry and CMS Doctors and Clinicians files. Payment figures come from the CMS Open Payments program for calendar year 2025. The directory refreshes monthly.
Do most Radiation Oncologists in California work in independent practices or large health systems?Among 516 Radiation Oncologists in California enrolled in Medicare, 16% bill through a solo or small practice with fewer than 10 clinicians, 17% through a mid-size group of 10 to 99, and 67% through a large group or health system with 100 or more clinicians, according to CMS enrollment records.
Which hospitals do Radiation Oncologists in California work at?According to CMS facility affiliation records, the California hospitals where the most Radiation Oncologists hold privileges are UCSF Medical Center in San Francisco; Stanford Health Care in Stanford; UC San Diego Health Hillcrest - Hillcrest Med Ctr in San Diego.
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