Our Radiation Oncologists have more than 45 years of total experience in the field of radiation oncology and with more than 4,000 CyberKnife cases, Colorado CyberKnife has one of the most experienced teams in the world.

C. Kelley Simpson, MD

C. Kelley Simpson, MD

Board Certified – American Board of Radiology – Radiation Oncology, 1994
Radiation Oncologist
Brachytherapy Specialist
Radiosurgery Specialist

Dr. Simpson’s clinical practice of radiation oncology includes:

  • LDR (low dose rate) brachytherapy
  • External beam radiation therapy – both IMRT & 3D IGRT
  • SRS, SRBT, & IGRT Robotic IMRT & 3D conformal with the CyberKnife VSI

Education and Practice History

  • Mississippi State, B.S., M.S., 1982
  • University of Mississippi, School of Medicine, 1986
  • University of Tennessee, Internship, internal medicine, 1986-1987
  • University of Colorado, Resident, radiation oncology, 1987-1989
  • University of Colorado, Chief Resident, radiation oncology, 1989-1990
  • William Beaumont, Fellowship, brachytherapy/hyperthermia, 1992-1993
  • Accuray CyberKnife University, radiation oncology training, 2010
  • Rocky Mountain Radiation Oncology & Centennial Radiation Oncology, P.C.
  • 20 years clinical experience serving the northern Colorado cities of Fort Collins, Loveland, and Greeley.

Brian Thorndyke, PhD, MS, DABR

Brian Thorndyke, PhD MS DABR

Senior Medical Physicist
Board Certified – Therapeutic Radiologic Physics – American Board of Radiology, 2010
Post Doctorate – Stanford University

Dr. Thorndyke brings a wealth of academic, clinical and training expertise in medical physics, imaging, and computer science, to Colorado CyberKnife:

Education and Practice History
    • University of Montreal, Quebec, B.S. physics, 1992
    • University of Montreal, Quebec, M.S. physics, 1992 – 1995
    • University of Florida, M.S., computer science, 1995 – 1997
    • University of Florida, PhD, physics, 1997 – 2004
    • Stanford University, post doctorate, radiation oncology, 2004 – 2006

Customer technical training for CyberKnife physicists, therapists, oncologists, and surgeons.

  • Support for onsite 4D Planning & 4D Commissioning
  • Medical Physicist, Oncure Medical Corp., Jacksonville, FL, 2006 – 2009
  • Primary CyberKnife Medical Physicist at CyberKnife Cancer Center
  • Supervised 2 dosimetrists and 5 radiation therapists.
  • Supervised junior physicist and QA at remote CyberKnife center
  • Assisted in commissioning (4) CyberKnife centers in Florida
  • Supported (2) external beam linear accelerator programs.

Professional Accomplishments

  • Emphasis on application of 4D CT & PET CT to IGRT
  • Novel imaging techniques such as optical & FLT-PET
  • Deformable image registration, 4D & Gated PET
  • Physics Training Specialist for Accuray, Inc., Sunnyvale, CA, 2009 – 2010
  • Dr. Thorndyke,  is well published, participating in over 50 journals and abstracts pertaining to stereotactic radiosurgery (SRS) treatment.
  • 3D & 4D rendering and imaging expert

Emilia Ripoll, MD

American Board of Urology
American Board of Holistic Medicine
Certified Yoga instructor
Qi Gong practitioner
Dr. Ripoll has been a prostate brachytherapy teacher and has traveled extensively throughout the United States teaching fellow urologist and radiation oncologists about this technique. More recently she has been involved in the use of High Frequency Ultrasound(HIFU) for the treatment of Prostate cancer.
Dr. Ripoll has a special interest in using nutritional and biological medicine in mitigating chemotherapy and radiation side effects; and believes strongly in the use of acupuncture for pain control.

Dr. Ripoll has published two books and has over thirty publications in the field of urology, most recently, a discussion of the benefit of acupuncture in the treatment of urologic conditions in the “World Journal of Urology.”
Originally from Barcelona, Spain, Dr. Ripoll received her medical degree from the University of Colorado Medical School with honors, where she subsequently completed her surgical internship and did a postdoctoral fellowship in prostate cancer.

Dr. Ripoll matriculated to the Baylor College of Medicine to complete her residency in urology and a fellowship in urological oncology. While at Baylor, Dr. Ripoll was an AFUD scholar, studying the role of early oncogenes in prostate cancer. Dr. Ripoll is double certified by the American Board of Urology and of Holistic Medicine. A certified yoga instructor and practitioner of Qi Gong, Dr. Ripoll has been utilizing acupuncture in the treatment of urological conditions. In addition to her special interest in how musculoskeletal disorders affect the urinary system, Dr. Ripoll has studied osteopathic manipulation.

Our Professional Administrative Staff:

Matthew P. O’Rourke, BS, MA

Chief Executive Officer

  • Responsible for management of operations, marketing, development, finance, physician-outreach, and contracting.
  • Ten years experience in healthcare, including serving as a specialty representative for Abbott Laboratories in oncology, health systems management, pediatrics, GI, rheumatology, internal medicine.
  • Six years operations, development and medical liaison experience in the Accuray CyberKnife community.
  • 20+ years operations, business management, and leadership experience.

Bonnie Sorden, RN

CyberKnife Clinical Coordinator

  • Coordinates and manages patients from initial consultation to treatment and follow-up care. Bonnie serves as patient educator and assists the doctors in all aspects of patient care.

Kyle White

MRI Technologist

  • Over 25 years of screening experience and the usage of MRI, CT, and Ultrasound Scanning equipment designed to better detect and treat cancers anywhere in the body.

Antonella Cody, BS, MA

Administrator/Patient Advocate

  • Assists in all aspects of the coordination of patient care, including intake of insurance information, medical record collection, diagnostic imaging collection, patient scheduling, and recording keeping.
  • Assists in accounting, executive management and vendor relations.

Anthony Cody


  • Processes all medical insurance pre-certifications, authorizations, claims, appeals, and denials for the center. Anthony goes to battle every day for patients to navigate the ever-changing waters of managed care, governmental payers, and annual/local coverage determination policies for SRS/SBRT radiosurgery.

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