Mercy Cancer Center Radiation Oncology has a team of six experienced physicians, board certified in radiation oncology, from the top cancer centers in the world.  An extensive staff of full-time physicists, nurses, dosimetrists, radiation therapists and dietitians ensure that patients receive individualized treatment planning, therapy and follow-up care.

Our Physicians

Richard L. Deming, MD

Radiation Oncologist

Medical Director

rdeming@mercydesmoines.org

Dr. Deming joined Mercy Cancer Center Radiation Oncology in 1989.

Education:

• Bachelor of Science degree, South Dakota State University, 1976
• Medical degree, Creighton University School of Medicine, 1980
• Internship in Internal Medicine, Naval Regional Medical Center, San Diego, 1981
• Residency in Radiation Oncology, University of California San Francisco, 1987
• Board certified in Radiation Oncology from the American Board of Radiology

Dr. Deming came to Mercy after spending two years on staff at the National Cancer Institute and National Naval Medical Center in Bethesda, Maryland.  He is the medical director for Mercy Cancer Center Radiation Oncology and medical director of the CyberKnife Radiosurgery Center of Iowa.  He also serves as the chairman of the Mercy Cancer Committee.  Dr. Deming is active in a number of professional oncology organizations.  He is president of the Iowa Society of Therapeutic Radiology.  He serves on the Expert Panel for Radiation Oncology for the American College of Radiology.  Dr. Deming is on the State Advisory Council of the American Cancer Society and is active in the Iowa Consortium for Comprehensive Cancer Care.  He is on the board of directors for the Iowa Oncology Research Association and is the past chairman of the radiation oncology committee for the North Central Cancer Treatment Group.  Dr. Deming is a charter member of the Des Moines chapter of the Lance Armstrong LiveStrong Foundation.  He is also a Susan G. Komen Society "Doctor for the Cure" and actively supports breast cancer advocacy in Iowa.

Dr. Deming is an avid adventurer. He enjoys running, cycling, swimming, triathlons, skiing and mountain climbing.

Philip J. Colletier, MD

Radiation Oncologist

pcolletier@mercydesmoines.org

Dr. Colletier joined Mercy Cancer Center Radiation Oncology in 1998.

Education

• Bachelor of Science degree in biology, University of Illinois, Urbana-Champaign, IL, 1985
• Medical degree, Rush Medical College, Chicago, 1989
• Internship, Letterman Army Medical Center, San Francisco, 1990
• Residency in Radiation Oncology, M.D. Anderson Cancer Center, Houston, 1998
• Board certified in Radiation Oncology by the American Board of Radiology

Dr. Colletier joined Mercy after completing his residency at the University of Texas MD Anderson Cancer Center in Houston.  Prior to his residency, Dr. Colletier served as the chief of ambulatory medicine for the Rock Island Arsenal Health Clinic and as battalion surgeon for the 1st Infantry Division during the Gulf War.  He is a member of several organizations including the American Society for Therapeutic Radiology and Oncology, the American Medical Association, the Radiological Society of North America, the Iowa Medical Society, Polk County Medical Society, the North Central Cancer Treatment Group and the Iowa Oncology Research Association.

He is an avid car enthusiast and enjoys boating and spending time with family.

John M. Martens

Radiation Oncologist

jmartens@mercydesmoines.org

Dr. Martens joined Mercy Cancer Center Radiation Oncology in 2002.

Education

• Doctor of Pharmacy, University of Nebraska Medical Center, 1993
• Doctor of Medicine, University of Nebraska Medical Center, 1997
• Internship, Iowa Methodist Internal Medicine Residency Program, 1998
• Residency, University Hospital in Cincinnati, where he served as chief resident, Radiation Oncology, 2002
• Board certified by the American Board of Radiology 

Dr. Martens is a member of the American Society for Therapeutic Radiology and Oncology, the Radiologic Society of North America, the American College of Radiology, the American Society of Clinical Oncology, the American Medical Association, the Iowa Medical Society, the Polk County Medical Society, the Iowa Oncology Research Association and the North Central Cancer Treatment Group.  Dr. Martens has research background in prostate cancer, lung cancer and trigeminal neuralgia, as well as extensive experience in neuro-oncology and gynecologic oncology.

He enjoys spending time with his family, tennis, ice hockey and painting.

Dev R. Puri, MD

Radiation Oncologist

dpuri@mercydesmoines.org

Dr. Puri joined Mercy Cancer Center Radiation Oncology in 2007.

Education:

• Bachelor’s degree, Stanford University, 1994
• Medical degree from the University of California, San Francisco, 2002
• Residency in Radiation Oncology at Memorial Sloan-Kettering Cancer Center, New York City, 2007
• Board certified by the American Board of Radiology

Dr. Puri is a member of the American Society for Therapeutic Radiology and Oncology, the American Society of Clinical Oncology, the Iowa Medical Society, the Iowa Oncology Research Association and the North Central Cancer Treatment Group. He is a recipient of the prestigious Patient’s Choice Award from vitals.com, a centralized online source of information on doctor performance based on patient feedback. On the research side, Dr. Puri has written on the use of sophisticated radiation techniques designed to maximize both tumor control rates and patients’ quality of life, and his work has been published in multiple peer-reviewed medical journals and textbooks. He has collaborated with radiation oncologists from some of the top cancer centers in the world – including the M.D. Anderson Cancer Center, Memorial Sloan-Kettering Cancer Center and the University of California, San Francisco, to develop radiotherapeutic recommendations for specific disease sites. 

In his spare time, Dr. Puri enjoys spending time outdoors with his family, reading and jogging.  

Derek L. Shickell, MD, MS

Radiation Oncologist

dshickell@mercydesmoines.org

Dr. Shickell joined Mercy Cancer Center Radiation Oncology in 2006.

Education:

• Undergraduate degree, Northwestern University, 1990
• Master’s degree, Medical Radiation Physics, Chicago Medical School, 1993
• Medical degree, University of Nebraska Medical Center, 1997
• Internship in Internal Medicine, University of Nebraska Medical Center, 1998
• Residency in Radiation Oncology, The Johns Hopkins Hospital, Baltimore, Maryland, 1998 – 2002. Chief resident, Radiation Oncology, 2001 - 2002
•  Board Certified in Radiation Oncology by the American Board of Radiology

Dr. Shickell served as a member of the Mayo Clinic’s Department of Radiation Oncology in Rochester, Minn., from 2002 through 2006.  In this clinical position, he specialized in breast and prostate cancer with an active interest in lung and GI malignancies.  In addition, he was active in the prostate and gynecological brachytherapy program.

Dr. Shickell has made national presentations at the Radiological Society of North America annual conference. Presentations included “Three Dimensional Analysis of Three Field Breast Irradiation” in 2000 and “Implanted Gold Fiducial Markers for Guiding Conformal External Beam Radiation Therapy” in 2001.

In his spare time, Dr. Shickell enjoys spending time with his growing family as well as golfing, reading and seeing movies. 

George H. Voynov, MD

Radiation Oncologist

gvoynov@mercydesmoines.org

Dr. Voynov joined Mercy Cancer Center Radiation Oncology in 2006.

Education:

• Bachelor’s degree, Connecticut College, 1996
• Medical degree, University of Connecticut, 2001
• Internship in Internal Medicine, Thomas Jefferson University, 2002 
• Residency in Radiation Oncology, University of Pittsburgh, 2006
• Board certified by the American Board of Radiology

Dr. Voynov has numerous publications and presentations on the use of stereotactic radiosurgery and intensity-modulated radiation therapy (IMRT) in optimizing patient outcomes while minimizing side effects of treatment in a wide variety of malignancies.  At the University of Pittsburgh, he received specialized training in the use of the CyberKnife® to treat tumors with high doses of radiation in a single session.

Dr. Voynov is a member of the American Society of Therapeutic Radiation Oncology, the American College of Radiology and actively participates in research trials and protocol reviews through the Iowa Oncology Research Association and the North Central Cancer Treatment Group.

In his spare time, he enjoys spending time with his family, reading and traveling.