Billy W. Loo Jr., MD PhD is a Professor of Radiation Oncology, a member of the Stanford Cancer Institute, and a member of the Molecular Imaging Program at Stanford (MIPS) in the Department of Radiology, in the School of Medicine. He is a physician-scientist Radiation Oncologist and Bioengineer who directs the Thoracic Radiation Oncology Program at Stanford.

His clinical specialties are state-of-the-art radiation therapy for lung/thoracic cancers, including stereotactic ablative radiotherapy (SABR) and 4-D image-guided radiation therapy for lung tumors. Dr. Loo is a recognized expert in thoracic cancers serving on multiple national committees (including as writing member, chair, or vice-chair) that publish clinical guidelines on the treatment of lung cancer and other thoracic malignancies, particularly the National Comprehensive Cancer Network (NCCN).

His clinical research is in clinical trials and implementation of new treatment techniques for lung cancer, and development of new medical imaging methods for measuring organ function and predicting response to cancer treatment. As part of this work, he leads a clinical and preclinical research program in molecular imaging, particularly using novel PET tracers for tumor hypoxia (EF5), tumor proliferation (FLT), and neuroinflammation (PBR06). He also co-leads clinical trials of novel applications of SABR including treatment of pulmonary emphysema and cardiac arrhythmias.

Since conceiving of a fundamentally new approach to delivering ultra-rapid, ultra-precise radiation therapy, pluridirectional high-energy agile scanning electronic radiotherapy (PHASER), Dr. Loo's major laboratory research focus has been to co-lead a collaborative effort between the Stanford Cancer Institute and SLAC National Accelerator Laboratory to develop PHASER into a transformative yet clinically practical technology. This program comprises both technology development and fundamental research on the radiobiology of extremely rapid FLASH radiation therapy to optimize the biological therapeutic index.

Dr. Loo received his MD from University of California, Davis and his PhD in Bioengineering from University of California, San Francisco and Berkeley. He completed his Radiation Oncology residency training at Stanford University. He is certified by the American Board of Radiology in Radiation Oncology, and is a Fellow of the American Society for Radiation Oncology (ASTRO).

Professional Summary

Professional Education
  • Residency: Stanford University Radiation Oncology Residency (2005) CA
  • Internship, Kaiser Permanente San Francisco Internal Medicine Residency, CA (2001)
  • Medical Education: University of California Davis School of Medicine (2000) CA
  • Board Certification: American Board of Radiology, Radiation Oncology (2006)
  • Ph.D., U.C. San Francisco, U.C. Berkeley, Bioengineering (2000)
  • A.B., U.C. Berkeley, Biophysics (1989)

Honors & Awards
  • Basic Science Travel Grant, ASTRO (2005)
  • Educator of the Year Award, Association of Residents in Radiation Oncology (2012)
  • Fellow of the American Society for Radiation Oncology (FASTRO), ASTRO (2021)
  • Graduate Student Research Award, University of California, San Francisco (1996)
  • Henry S. Kaplan Memorial Prize for Teaching, Stanford University (2021)
  • Henry S. Kaplan Memorial Prize for Teaching in Radiation Oncology, Stanford University (2009)
  • Laboratory Graduate Fellowship, Associated Western Universities (1994, 1995)
  • Malcolm A. Bagshaw Award, Stanford Radiation Oncology (2003)
  • Molecular Biology in Clinical Oncology Workshop Scholarship, AACR (2004)
  • Rapp/Rummelsberg Research Scholarship, - (1991)
  • Regents Fellowship, University of California (1996)
  • Research Scholarship, California Medical Education and Research Foundation (1992)
  • Roentgen Resident/Fellow Research Award, RSNA (2004)
  • StartX Professor in Residence, StartX (2021)
  • Travel Grant Award, Best of ASCO Meeting, Denver, ASCO (2004)
  • Young Investigator Travel Grant, ECOG (2005)

Administrative Appointments
  • Director of New Technologies, Radiation Oncology (2011 - Present)
  • Director of Thoracic Radiation Oncology, Radiation Oncology (2005 - Present)
  • Director of VA Radiation Oncology Services, Radiation Oncology (2019 - Present)


Clinical Trials

Clinical trials are research studies that evaluate a new medical approach, device, drug, or other treatment. As a Stanford Health Care patient, you may have access to the latest, advanced clinical trials.

Open trials refer to studies currently accepting participants. Closed trials are not currently enrolling, but may open in the future.

Practice Locations

Radiation Oncology at Blake Wilbur Building Palo Alto, CA
Palo Alto, CA

875 Blake Wilbur Drive

Palo Alto , CA 94304

(650) 498-6000

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Thoracic Cancer Program in Palo Alto Palo Alto, CA
Palo Alto, CA

875 Blake Wilbur Drive

Palo Alto , CA 94304

(650) 498-6000

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CyberKnife Stereotactic Radiosurgery Program at Advanced Medicine Center Building Palo Alto, CA
Palo Alto, CA

875 Blake Wilbur Drive, Clinic D

Palo Alto , CA 94304

(650) 725-0084

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Patient Ratings

(35 Ratings)

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Patient Reviews

(47 reviews)

My doctor in radiation oncology is consistently professional, caring, answers any questions, and considerate of my goals.
Dr. Loo did not rush ad took as much time as I needed.
Dr. Loo excellent his resident was outstanding as well.
I didn't know what questions to ask. As the suggested procedure was change from spot radiation to a full lung treatment. I should have asked more question about the dr.'s work with this procedure & the success rate. Am not waiting to get a second opinion... I just need to make sure this is the best treatment for me. However, I did like Dr. Loo. So hopeful we can proceed.
Dr. Loo is a great doctor.
Love Dr. Loo & his team!
Dr. Loo is excellent -
Dr. Billy Loo is excellent.
Dr. Loo is fabulous!
My doctors at Stanford have always been top quality.
I marked both "fair" & 'good' or 'good' and 'very good' when my judgment was between these 2 marks.
all was well informed with information given.
Dr. Loo and his team are excellent.
Dr. Loo is the best!
Always good.
Dr. Loo is very good.
I have great confidence with all of Dr. Bicly Loris team, in most legger I ended up with Dr. far as my seeing concern lactar.
All good.
Dr. Billy W. Loo was extremely professional with excellent bedside manner.
Dr. Loo and his entire team are superb!
Dr. Billy Loo is excellent & a good communicator. I am fortunate to have him as my radiologist/oncologist.
Dr. Loo answered all questions & I was not rushed.
Dr. Loo is excellent in all ways!
Dr. Loo is wonderful - smart, explains everything well, answers all my questions.
I am very fortunate to have Dr. Loo as my doctor.
I could not ask for anything better.
I would absolutely recommend Dr. Loo to others. Every time I meet with him he is very accessible, informative and respectful.
Large wait time to see doctor.
Dr. Loo is more than I could ever ask for in a doctor!!! I have already referred 2 people to him.
Dr. Loo is very calming - excellent.
I am so lucky to have Dr. Loo. I love him!
Dr. Loo is a fantastic Dr. he always takes the time to carefully explain the test results and options. He also makes sure all our questions are answered.
As usual Dr. Bill Loo was extremely professional, understanding and caring. His direct gaze and soft gentle voice manifest his sincerity.
I could not ask for anything more than Dr. Loo. He is fantastic.
Most satisfied.
Dr. Loo is great. Student/resident needed instruction to wash/sterilize hands before coming in room!
Dr. Loo is a fantastic doctor. I am fortunate to have him! His calm demeanor is so wonderful in a stressful situation.
Dr. Loo is great!
I have complete confidence in Dr. Loo.
I am highly satisfied with my treatment team and care received.
The experience and helpfulness was very good.
Just great.
I had a very good experience with everyone their & was treated very well.
Dr. Loo is fantastic especially in a stressful situation.

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